Thoughts on the Meaning of "Deathly Hallows"

I was initially puzzled by the news that Book 7 would be titled Harry Potter and the Deathly Hallows. But Rowling is a fabulous wordsmith, and I believe she’s simultaneously working with multiple meanings in the phrase “deathly hallows.”   While the word “deathly” would seem plainly to mean ‘relating to or suggestive of death,’ “hallows” is an uncommon word less clear in meaning. American dictionaries only offer limited definitions for “hallow”; however, the Oxford English Dictionary offers numerous definitions for “hallow” in different parts of speech (listed below and expanded on 12-29).  I believe both the noun and verb definitions are pertinent to the story and what we know or strongly suspect will happen in Book 7, Harry Potter and the Deathly Hallows.
Oxford English Dictionary entries:
Hallow, Noun (1)
1. A holy personage, a saint. (Little used after 1500, and now preserved only in All-Hallows and its combinations, q.v.)
2. In pl. applied to the shrines or relics of saints; the gods of the heathen or their shrines. In the phrase to seek hallows, to visit the shrines or relics of saints; orig. as in sense 1, the saints themselves being thought of as present at their shrines. Cf. quot. c1440 in 1.
3. hallow- in Comb. (chiefly in Sc.) is used for All-Hallow- = All Saints'-, in Hallow-day, Hallow-e'en, Hallowmas, Hallow-tide; also hallow-fair, a fair or market held at Hallowmas; hallow-fire, a bonfire kindled on All-hallow-e'en, an ancient Celtic observance.
Hallow, Noun (2)
A loud shout or cry, to incite dogs in the chase, to help combined effort, or to attract attention.
Hallow, Noun (3)
Obs. The parts of the hare given to hounds as a reward or encouragement after a successful chase.
Hallow, Verb (1)
1. trans. To make holy; to sanctify, purify.
2. To consecrate, set apart (a person or thing) as sacred to God; to dedicate to some sacred or religious use or office; to bless a thing so that it may be under the particular protection of a deity, or possess divine virtue. arch.
3. To honour as holy, to regard and treat with reverence or awe (esp. God or his name).
4. trans. To keep (a day, festival, etc.) holy; to observe solemnly.
Hallow, Verb (2)
1. trans. a. To chase or pursue with shouts. b. To urge on or incite with shouts. c. To call or summon in, back, etc. with shouting.
2. intr. To shout, in order to urge on dogs to the chase, assist combined effort, or attract attention.
3. trans. To shout (something) aloud.
Hallow, int.
Obs. An exclamation to arouse to action, or to excite attention.
Hallow: obscure form of Hollow
Deathly, Adjective
†1. Subject to death, mortal. Obs.
2. Causing death, deadly.
3. Of the nature of or resembling death, deathlike; gloomy, pale, etc. as death.
4. Of or pertaining to death. poetical.
Deathly, Adverb
†1. In a way causing or tending to death. Obs.
2. To a degree resembling death.
In the context of the series to date and what we know or strongly suspect will happen in the final book, it seems to me that Rowling is playing off multiple meanings simultaneously.
In terms of “hallows” as holy persons or saints (generally dead), we have James & Lily Potter, Sirius Black, and Albus Dumbledore, all dead and all “sanctified” persons in the story. The Christian references to each character are evident: James & Lily had Harry christened, Sirius was Harry’s godfather, and Dumbledore was closely associated with a traditional Christ-symbol, the phoenix (resurrection bird).
In Book 7, we know or expect Harry will “seek hallows” by making a type of pilgrimage to the place associated with those “sanctified” persons: Godric’s Hollow (Lily & James), 12 Grimmauld Place (Sirius), and Hogwarts (Dumbledore).
We expect Harry will find key information in each place that will help him to hunt and destroy Voldemort’s Horcruxes and ultimately vanquish Voldemort. In a manner of speaking, these people will “hallow” or call out to Harry from death and incite him and/or help him in combination in his quest to hunt the Horcruxes. We’ve seen an example of a type of “deathly hallow” at the end of GoF when the shades of Lily & James called out instructions to Harry that enabled him to escape the graveyard. I don’t expect any of these people to return as shades as in the Priori Incantatem spell nor do I expect Dumbledore will return as a ghost, but in a less dramatic fashion, they will all help Harry in Book 7 from beyond the grave. Harry will find an object or information at Godric’s Hollow that will help him, Harry will consult Dumbledore’s portrait at Hogwarts and possibly receive items and information (memories, pensieve, letter) that Dumbledore left behind for him, and Harry has already received assistance from Sirius by inheriting 12 Grimmauld Place, the Black mansion where the heavy gold locket was in OotP. I suspect the visit to 12GP, only possible because of Sirius left it to Harry, will enable the trio to unravel the puzzle of the fake Horcrux and note from RAB. Perhaps Harry will also be able to communicate with Sirius through the Veil in the DoM, although I find that scenario possible but not highly likely to happen.
In the non-Christian sense, hallows per the OED would also refer to Voldemort’s "heathen" Horcruxes and the places in which he has hidden them, each place having great significance to him because it was where he demonstrated his brilliance and magical superiority. He hid the Peverell ring in the Gaunt ruins where he framed Morfin for the Riddles’ murders, he meant to hide the Slytherin locket in the cave where he tortured two orphans with powers he had developed on his own, and he planned to use the diary at Hogwarts to release the basilisk from the Chamber of Secrets, just as he had done as a student when he killed Moaning Myrtle. So Harry will also be “seeking hallows” in Book 7 as he hunts for and destroys the remaining Horcruxes in the “shrines” where Voldemort has hidden them.
The phrase “deathly hallows” is a particularly good description for the Horcruxes themselves since the soul itself is a holy thing, but Voldemort has torn his and encased each soul fragment in an object to create a Horcrux, “wickedest of magical inventions.” The Horcruxes are examples of something good that has been perverted to an evil purpose, and Voldemort has effectively killed his humanity by making them.
For Harry, the destroyed Horcruxes will each be a type of “hallow” in the sense of a reward for a successful Horcrux hunt.
In the sense of the meaning "to make holy," the successive destruction of Voldemort's Horcruxes will possibly cause the soul fragments to reunite behind the Veil (my theory), which will ultimately make Voldemort's spirit whole again when the seventh part of his soul residing in his maimed body is released.  In other words, just as the Horcruxes form individual anchors on earth so that Voldemort cannot be killed even if his body is destroyed, the soul fragments from the destroyed Horcruxes will go behind the Veil and reunite, forming a new anchor; when the seventh part of his soul is finally separated from his body, it will be drawn behind the Veil with the others.  This is the only way I can see to prevent Voldemort from staying behind as a ghost.  Voldemort is terrified of death just as Sir Nicholas was, so something (like the new anchor) will have to be in place to prevent him from staying behind. 

Finally, we will probably see Harry putting each destroyed Horcrux vessel to good use, thereby reversing the corruption of the object from being turned into a Horcrux and effectively making it good (holy) again. We saw Dumbledore using the destroyed ring to show Slughorn that Voldemort was not invincible and to convince him to return to Hogwarts and help the Order, and we saw Harry use the destroyed diary to free Dobby.
And just adding another thought that Harry's wand wood--holly--also ties in with the idea of Harry making things whole and holy again since the OED lists "holy" as a variant spelling of holly and since the wood is associated with resurrection, eternal life, and holiness.  As many already know, Harry's holly wood is contrasted with Voldemort's yew wand wood (eternal life but also poison).
If Rowling is playing will all these meanings as I suspect she is, then my conclusion is that Harry Potter and the Deathly Hallows is a brilliant title for the last book.
[UPDATE December 27, 2006
I’m adding further information to fuel our speculation that was prompted by reading the latest entries in Potter websites that I follow (these personal favorites are linked a little further down).
I still believe the title is brilliant for all the reasons stated above, but when I wrote the original entry for this post, I hadn’t fully considered that the title would have to have an element of mystery to be consistent with Rowling's other titles, and particularly since this is her final and most-anticipated book. In my 12-23 comment below to focusf1, I wrote that I had just been reading comments pointing to a graveyard at Hogwarts based on something one of the HP movie directors had mentioned that is getting serious consideration relative to the new book title. Here is the 2004 quote that I looked up today on Accio Quote (
Alfonso Cuaron: We needed a place where the kids could see the execution of Buckbeak, and we thought about having a graveyard. And we consulted Jo about it and she said "No, the graveyard is not there," and I said "Why?" And then she gave me the whole explanation of why the graveyard cannot be there, because it's in a different place of the castle. Because it's going to play...and she knows her thing, she knows exactly what's going to happen later. And once I remember having little people in some storyboards, playing some keyboards and an organ in the Great Hall. And Jo said "No, there are no little people in this universe." I said "Yes, it's like..." she says, "Yes, lovely image, but they don't make sense in this universe."
I never paid much attention to that quote, and it’s getting a lot of justified attention on HP forums because of “Deathly Hallows.” Cuaron (director of Prisoner of Azkaban) hints that Rowling said this Hogwarts graveyard would play a role in the story, and we haven’t see a graveyard at Hogwarts to date. Taking a hint from Travis in the comments below, I looked up the discussion regarding Dumbledore’s request to be buried at Hogwarts. As McGonagall told the other teachers about Dumbledore’s request, she said it would be up to the Ministry since “No other headmaster or headmistress has ever been—.“ (HBP29)  This is interesting because if the Hogwarts graveyard isn’t for the former heads, then who is buried there (since if not the former heads, then certainly not the teachers, groundskeepers, and castle elves)?  Doesn’t this suggest that the Hogwarts graveyard must contain the remains of the three Founders who stayed with the school (Godric Gryffindor, Rowena Ravenclaw, and Helga Hufflepuff)?
Moreover, several sharp readers have pointed out that Tolkien referred to a burial place in LOTR as the Hallows. I followed that hint as well and looked up those passages, and while I am not claiming that LOTR gives us the key to the meaning of Deathly Hallows, Rowling is admittedly a great borrower and adapter of legends, myths, folklore, and works of literature that influenced her—taking what she likes and making it uniquely her own with a twist or two. The similarities between the stories in the HP series and LOTR are only superficial, but I can believe she was influenced by works like LOTR and did adapt the bits she really liked for use in the HP books (just as she adapted alchemical imagery, Arthurian legends, folklore, etc.).  That would include names and their associations.   For example, in LOTR, the ill in Gondor are taken to the Houses of Healing where they are tended by Healers.  Filch's cat Mrs. Norris is named for one of Jane Austin's nosiest characters.  Certain characters and words do stick with her, and she does use them.
In a 2000 interview on, Rowling said she had read LOTR at age 19 (
Question: Hello, I was wondering how much Tolkien inspired and influenced your writing?
J.K. Rowling responds: Hard to say. I didn't read The Hobbit until after the first Harry book was written, though I read Lord of the Rings when I was nineteen. I think, setting aside the obvious fact that we both use myth and legend, that the similarities are fairly superficial. Tolkien created a whole new mythology, which I would never claim to have done. On the other hand, I think I have better jokes.
The LOTR contains a burial place in Gondor that Gandalf and Aragorn both refer to as the Hallows. The following quotes are taken from my 1994 Houghton Mifflin paperback edition of LOTR. The passages refer to the passages in which Denethor, the Steward of Gondor who has gone mad, is taking his feverish and unconscious son Faramir to the houses of the dead where he plans to burn himself and Faramir on a funeral pyre:
“Then they went on through the Citadel gate, where the sentinel stared at them in wonder and dismay as they passed by. Turning westward, they came at length to a door in the rearward wall of the sixth circle. Fen Hollen it was called, for it was kept ever shut save at times of funeral, and only the Lord of the City might use it that way, or those who bore the token of the tombs and tended the houses of the dead. Beyond it went a winding road that descended in many curves down to the narrow land under the shadow of Mindolluin’s precipice where stood the mansions of the dead Kings and of their Stewards.
A porter sat in a little house beside the way, and with fear in his eyes, he came forth bearing a lantern in his hand. At the Lord’s command he unlocked the door, and silently it swung back; and they passed through, taking the lantern from his hand. It was dark on the climbing road between ancient walls and many-pillared balusters looking in the swaying lantern-beam. Their slow feet echoed as they walked down, down, until at last they came to the Silent Street, Rath Dinen, between pale domes and empty halls and images of men long dead; and they entered the House of the Steward and set down their burden.
There Pippin, staring uneasily about him, saw that he was in a wide vaulted chamber, draped as it were with the great shadows that the little lantern threw upon its shrouded walls. And dimly to be seen were many rows of tables, carved of marble; and upon each table lay a sleeping form, hands folded, head pillowed upon stone.” Page 808
Denethor then released Pippin from his duties, and Pippin ran to find Gandalf. Pippin and Gandalf quickly returned to the tombs, where Gandalf confronted Denethor:
“What is this, my Lord?” said the wizard. “The houses of the dead are no places for the living. And why do men fight here in the Hallows when there is war enough before the Gate? Or has our Enemy come even to Rath Dinen?” Page 834
Aragorn later spoke the following to Beregond: “Beregond, by your sword blood was spilled in the Hallows, where that is forbidden. Page 947
I was so struck when I reread those passages. The first thing I noticed was that the LOTR characters descended to the Hallows; similarly, as John Granger often points out, at the end of every HP book, Harry has died a figurative death in a place that is literally or figuratively a kind of “underworld" or "lower realm” (John also notes that Harry is figuratively resurrected each time in the presence of a symbolic Christ-figure):
HP1: Harry dropped through a trap door in the floor to reach the series of enchantments
HP2: Harry slid through a tunnel in Myrtle’s bathroom to reach the Chamber of Secrets
HP3: Harry went down to the Hogwarts lake to help Sirius fight off the dementors (in the first book, we learned that the castle is visible from the lake, but high above the lake on a nearby mountaintop)
HP4: Harry was portkeyed to the graveyard in Little Hangleton, which was below the Riddle house, set on a nearby hillside, from whence Wormtail and Voldemort came to meet Harry
HP5: Harry descended to the Department of Mysteries
HP6 Harry descended a cliff to reach the sea cave
So I asked myself, is the reason no character has ever mentioned the Hogwarts graveyard to date that it’s below ground and the entrance does not indicate that it is a burial place? And if "Hallows" in the new title refers to a Hogwarts burial place, does "Deathly" mean that's where Harry will experience his figurative death in the last book (possibly, as Janet has speculated, tied to the Draught of Living Death, which has been amply set up but never paid off)? I can't believe Rowling would truly kill Harry off.
The second thing that struck me is that the entrance to the Hallows in LOTR is only accessible to a small and exclusive group of people (the Lord of the City or those bearing "the token of the tombs").   I don't know what Tolkien meant by the phrase "token of the tombs," but Harry, in the first five books has had to possess special knowledge or power or use a special object or some combination of those in order to succeed, and these things were known to only a very small and exclusive group of people. HBP broke the pattern because it's a two-parter with Book 7 so we didn't have the kind of resolution at the end as we did with the first five books. But it's something else to think about if indeed the Hallows of "Deathly Hallows" refers to the tomb of GG, RR, and HH.
The third thing I noticed was that in the LOTR, the Hallows are reserved for Gondor royalty (although two hobbits were eventually buried there next to Aragorn). Who could be considered Hogwarts royalty if not the Founders? And notably, in the scene describing Dumbledore's funeral and the creation of the White Tomb at the end of HBP, there are no other tombs or mausoleums described nearby, so if the Hallows in "Deathly Hallows" refers to the burial place of three Founders on the castle grounds, there is a tie-in with the meaning of hallowed as being "set apart." And was Harry Potter and the Hallows of Hogwarts the title Rowling said was ahead by a short nose (two consonants and a vowel) a few weeks ago?  If so, then even more reason to believe that the Hallows of the new title is specific to Hogwarts.
{Additional update 12-29. As I was skimming LOTR, I found another use of the word “hallow” used in the obscure sense of “hollow.” It is used twice at the end of the book to refer to a depression or hollow on the side of Mount Mindolluin where Gandalf and Aragorn find a sapling of the White Tree growing: “ . . . and there they found a path made in ages past that few now dared to tread. For it led up on to the mountain to a high hallow where only the kings had been wont to go.” Page 949 End mini-update}
None of this information nails down the meaning of "Deathly Hallows," but the Cuaron quote and Tolkien passages do, IMO, make me love this title even more and make me more eager to see what surprises Rowling has for us in the last book.
Special thanks to Janet, Travis, Pauli, and John (and the people they link to) for the suggestions that led to this update. Their weblogs/websites are all worth reading (on an ongoing basis), and especially for Book 7 title speculation. Although they all overlap to a degree in considering the various Book 7 theories currently in play, each one offers his or her own perspective in speculating about the new title:
Professional Hollywood screenwriter and teacher of screenwriting Janet Batchler at Quoth the Maven ( thinks Deathly Hallows will refer to a place we haven’t seen before. If you haven’t read Janet’s new book, What Will Harry Do? (Book 7 speculations based on the plot set-ups she’s pulled from canon and where she thinks they’ll lead), then you’re missing out on some excellent speculation.
Travis Prinzi at Sword of Gryffindor ( and Hog’s Head Pubcasts has some thoughts of his own about the new title in several posts and pubcasts and considers other theories floating around. If you haven’t been reading his website or listening to his entertaining pubcasts (10 so far!), you might want to start. Note: The Arthurian legends have been much-discussed on the forums in relation to “Deathly Hallows,” and Travis had a post about the links between HP and the Arthurian legends over a year ago!
Pauli at Muggle Matters ( has several posts about the title that involve his own preliminary thoughts and later commentary on theories he’s been reading.
John Granger at Hogwarts Professor ( is an expert on the alchemical imagery in the HP series. His new weblog debuts with an excellent post on the new title and the alchemical meaning of the new title. John’s latest book, Unlocking Harry Potter: Five Keys for the Serious Reader, will be available in January 2007. Travis Prinzi read and reviewed the draft a few months ago and highly recommends it for the serious Potter fan. The book may be pre-ordered at END UPDATE]

Oxford English Dictionary entries for Hallow:
Hallow, n. (1)
   1. A holy personage, a saint. (Little used after 1500, and now preserved only in All-Hallows and its combinations, q.v.)
   a885 Will of Alfred in Earle Land Ch. 148 On godes naman and on his hali¼ra. c1000 Ælfric Hom. II. 142 Cuðberhtus se hal¼a siððan ¼efremode mihti¼lice wundra on ðam mynstre wuni¼ende. c1000 I Saints' Lives (E.E.T.S.) II. 52 Swa swa seo hali¼e [St. Mary] ær foresæde. 1154 O.E. Chron. an. 1137 §5 Hi sæden openlice ðæt crist slep & his halechen. c1200 Trin. Coll. Hom. 5 Ure louerd wile cume and alle his haleŠen mid him. c1200 Ormin 6009 Bitwenenn Godess hallŠhenn. a1225 Juliana 76 As hit deh alhen [MS. B. halhe] to donne. 1230 Hali Meid. 19 Dream+þat nane halwes ne mahen. a1240 Lofsong in Cott. Hom. 217 Imennesse of haluwen. c1290 S. Eng. Leg. I. 53/227 HeiŠ halewe in heouene is. 1297 R. Glouc. (1724) 82 Grete halwe+As Seynt Cristyne & Seynt Fey. Ibid. 233 Mony ys the holy halwe, that her y bured ys. Ibid. 255 Ye relykes of halewen yfounde were. a1300 Cursor M. 10402 Of halus hei in heuen blis. Ibid. 29549 (Cott. Galba) It takes him fro þe cumpany of halows. c1300 Ibid. 22592 (Edin.) Es na halŠie [v. rr. halu, halwe] vndir þe heuin. 13+ Sir Beues 1218 (MS. A.) Deliure a þef fro þe galwe, He þe hateþafter be alle halwe! [v. rr. alle halowse, al halowes]. c1325 Prose Psalter li[i]. 9 In þe syŠt of þyn halwen. c1330 R. Brunne Chron. (1810) 182, I vowe to Saynt Michael, & tille halwes þat are. 1340 Hampole Psalter v. 15 Ymange aungels & haloghs. 1340 I Pr. Consc. 5119 Alle his halghes sal with him come. c1350 Will. Palerne 371 To crist & to hal alwes. c1380 Wyclif Wks. (1880) 48 Acursed of god of fraunseis and of alle hawen. c1386 Chaucer Prol. 14 To ferne halwes [v.r. halowes] kowthe in sondry londes. 1387 Trevisa Higden (Rolls) I. A chirche of al halwen+oure Lady is after Crist cheef halwe of al mankynde. c1400 Mandeville (Roxb.) xiii. 60 Him þai honoure and wirschepes before all oþer halowes. c1430 Pilgr. Lyf Manhode ii. cxlvii. (1869) 133 Ayenst god and alle hise halwen. c1440 Sir Gowther 380 Yet may she sum good halowe seche. c1489 Caxton Sonnes of Aymon iii. 99, I swere you vpon all halowes.  Ibid. xix. 418, I swere to you, sire, by all halowen. 1553 Becon Reliques of Rome (1563) 238 Martyrs, Confessours, and virgines, and the halowes of God. 1647 Pol. Ballads (1860) I. 67 Watson, thee I long to see By God, and by the Hallowes. [1876 Freeman Norm. Conq. V. 284 Men said openly that Christ slept and His hallows. (See quot. 1154.)] 
   2. In pl. applied to the shrines or relics of saints; the gods of the heathen or their shrines.
   In the phrase to seek hallows, to visit the shrines or relics of saints; orig. as in sense 1, the saints themselves being thought of as present at their shrines. Cf. quot. c1440 in 1.
   c1200 Vices & Virtues (1888) 3 Ðo menn ðe halleð gode behaten god te donne, oðer halŠe to sechen. c1385 Chaucer L.G.W. 1310 Dido, Sche sekith halwis & doth sacryfise. c1400 Destr. Troy 650 Swiftly to sweire vpon swete haloghes. Ibid. 10948 With Sacrifice solemne [þai] soghten þere halowes. c1489 Caxton Sonnes of Aymon xxvi. 552, I wylle+that ye bere wyth you the halowes for to make theym swere thervpon. 1523 Skelton Garl. Laurel 1636 Right is over the fallows Gone to seke hallows. 1561 Schole-ho. Wom. 309 in Hazl. E.P.P. IV. 117 On pilgremage then must they go, To Wilsdon, Barking, or to some hallowes. 
   b. holy of hallows: see holy.
   3. hallow- in Comb. (chiefly in Sc.) is used for All-Hallow- = All Saints'-, in Hallow-day, Hallow-e'en, Hallowmas, Hallow-tide; also hallow-fair, a fair or market held at Hallowmas; hallow-fire, a bonfire kindled on All-hallow-e'en, an ancient Celtic observance.
   1795 Macpherson Wyntoun's Cron. Gloss., Halow-fair is held on the day of all saints. 1799 Statist. Acc. Scotl. XXI. 145 (Jam.) But now the hallow fire, when kindled, is attended by children only. 
Hallow, n. (2)
   A loud shout or cry, to incite dogs in the chase, to help combined effort, or to attract attention.
   c1440 Promp. Parv. 223/2 Halow, schypmannys crye, celeuma. 1583 Stanyhurst Æneis ii. (Arb.) 45 With shouting clamorus hallow. 1603 Drayton Bar Wars ii. (R.), With noise of hounds and halloos as distraught. 1634 Milton Comus 481 List! list! I hear Some far-off hallo break the silent air. 1783 Cowper Epit. Hare 4 Whose foot ne'er tainted morning dew, Nor ear heard huntsmen's hallo. 1837 W. Irving Capt. Bonneville III. 226 Gallopping, with whoop and halloo, into the camp. 
Hallow, n. (3)
   The parts of the hare given to hounds as a reward or encouragement after a successful chase.
   c1420 Venery de Twety in Rel. Ant. I. 153 Whan the hare is take, and your houndes have ronne wele to hym ye shul blowe aftirward, and ye shul yef to your houndes the halow, and that is the syde, the shuldres, the nekke, and the hed, and the loyne shal to kechonne. 1486 Bk. St. Albans Eiijb, Wich rewarde when oon the erth it is dalt With all goode hunteris the halow it is calt. 1576 Turberv. Venerie 174 Which the Frenchman calleth the reward, and sometimes the quarey, but our old Tristram calleth it the hallow. 1688 R. Holme Armoury ii. 188/1 Hallow+a reward given to Hounds, of beast that are not beasts of Venery. 
Hallow. V. (1)
   1. trans. To make holy; to sanctify, purify.
   c1000 Ags. Gosp. John xvii. 19 Ic hal¼i¼e me sylfne þæt hi¼ syn eac ¼ehal¼ode. c1000 Ælfric Exod. xix. 10 „ehal¼a hi¼ todæ¼. c1200 Ormin 10803 He wollde uss hallŠhenn. a1225 Ancr. R. 396 Jesu Cristes blod þet haleweð boð þeos oðre. a1340 Hampole Psalter xvii. 28 Traist in him þat he will halighe þe. 1340 Ayenb. 237 MiŠtoul uor to halŠy ham þet hit onderuongeþ. 1382 Wyclif John xi. 55 Many of the cuntree stiŠeden vp to Jerusalem the day bifore pask, for to halowe them selue. Ibid. xvii. 17 Halwe thou hem in treuthe. c1532 G. Du Wes Introd. Fr. in Palsgr. 954 To halowe, sainctifier. 1638 Baker tr. Balzac's Lett. (vol. III). 25 Those women whose teares Antiquitie hath hallowed. 1837 R. Nicoll Poems (1843) 1 Chief of the Household Gods Which hallow Scotland's lowly cottage-homes! 1892 Westcott Gospel of Life 299 Christianity+meets and hallows our broadest views of nature and life. 
   2. To consecrate, set apart (a person or thing) as sacred to God; to dedicate to some sacred or religious use or office; to bless a thing so that it may be under the particular protection of a deity, or possess divine virtue. arch.
   971 Blickl. Hom. 205 Gif hit sie mannes ¼emet þæt he ciricean hal¼ian sceole. a1175 Cott. Hom. 223 On þan seofeðan deŠ he Šeendode his wurc+and þane deŠ halŠode. c1205 Lay. 17496 Þe king+hæt halŠien þe stude, þe hæhte Stanhenge. 1297 R. Glouc. (1724) 358 The pope asoyled & blessed Wyllam & al hys+And halewede hys baner. a1300 Cursor M. 8867 Quen þat þe templehalughd was. 1398 Trevisa Barth. De P.R. xvi. lxxxvi. (1495) 582 Saphire stone was syngulerly halowed to Appolin. 1494 Fabyan Chron. I. cxxxii. (R.), For to dedicate and halowe the monastery of Seynt Denys in moost solempne wyse. 1547 Boorde Introd. Knowl. i. (1870) 121 The Kynges of Englande doth halowe euery yere Crampe rynges. 1579 Spenser Sheph. Cal. Feb. 210 Often crost with the priestes crewe, And often halowed with holy water dewe. 1648 Gage West. Ind. 152 Candlemas day+Bring their Candles to be blessed and hallowed. 1868 Freeman Norm. Conq. II. vii. 112 Leo+entered France+to hallow the newly built church of his monastery. 
   †b. To consecrate (a person) to an office, as bishop, king, etc. Obs.
   c900 tr. Bæda's Hist. i. xvi. [xxvii.] (1890) 62 Se hal¼a wer Agustinus+wæs ¼ehal¼od ercebiscop Ongolþeode. c1000 O.E. Chron. an. 979 On þys ¼eare wæs Æþelred to cininge ¼ehal¼od. 1154 Ibid. an. 1135 And halechede him to kinge on midewintre dæi. c1325 Metr. Hom. 79 Thir nonnes when that thai halowid ware, Thai toke thaire leue hame to fare. [1871 Freeman Norm. Conq. IV. xviii. 179 And there+the Lady Matilda was hallowed to Queen by Archbishop Ealdred. 1872 E. W. Robertson Hist. Ess. 207 In the reign of Offa+Ecgfrith was ‘hallowed to king’.] 
   †c. To consecrate (the eucharistic elements). Obs.
   c1200 Ormin 1727 Þær he Cristess flæsh and blod Hanndleþþ, hallŠheþþ, and offreþþ. 
   3. To honour as holy, to regard and treat with reverence or awe (esp. God or his name).
   a1000 Hymns v. 2 (Gr.) Sy þinum weorcum hal¼ad noma niðða bearnum! c1000 Ags. Gosp. Matt. vi. 9 Fader ure þu þe ert on heofene, sye þin name ¼ehal¼ed. a1300 Cursor M. 25104 Halud be þi nam to neuen. 1382 Wyclif Deut. xxxii. 51 „e halwide not me amonge the sones of Yrael. a1440 Sir Degrev. 91 They hade halowed hys name Wyth gret nobullé. c1600 Shakes. Sonn. cviii, Euen as when first I hallowed thy faire name. 1611 Bible Matt. vi. 9 Our father which art in heauen, hallowed be thy Name. 1645 Ussher Body Div. (1647) 358 To hallow the name of God, is to separate it from all profane and unholy abuse, to a holy and reverend use. 
   4. trans. To keep (a day, festival, etc.) holy; to observe solemnly.
   971 Blickl. Hom. 37 Hal¼iaþ eower fæsten. c1175 Lamb. Hom. 45 To haliŠen and to wurðien þenne dei þe is icleped sunne dei. c1380 Wyclif Sel. Wks. III. 85 Have mynde to halwe þin holiday. 1389 Eng. Gilds (1870) 17 Euery brother & sister+shullen halwen euermore ye day of seint George. a1533 Ld. Berners Gold. Bk. M. Aurel. (1546) Dvijb, Halowyng the feaste of themperours natiuitie. 1552 Abp. Hamilton Catech. (1884) 66 Remember that thow hallow the Sabboth day. 1796 Coleridge Left Place of Retirement 10 Hallowing his Sabbath-day by quietness. 
   †b. absol. To keep holy day. Obs.
   c1200 Trin. Coll. Hom. 155 Hure riht time þenne men fasten shal oðer halŠen. 1303 R. Brunne Handl. Synne 929 Haleweþ wyþ us at þe noun In þe wurschyp of oure lady. 1496 Dives & Paup. (W. de W.) i. xviii. 51/1 Tyme to halowe and tyme to labour. 
Hallow, v. (2)
   1. trans. a. To chase or pursue with shouts. b. To urge on or incite with shouts. c. To call or summon in, back, etc. with shouting.
   c1340 Cursor M. (Trin.) 15833 Þei+foule halowed him+as he had ben an hounde. c1369 Chaucer Dethe Blaunche 379 Þe hert found is I-halowed and rechased fast long tyme. 1399 Langl. Rich. Redeles iii. 228 He was halowid and y-huntid, and y-hote trusse. 1530 Palsgr. 577/2, I halowe houndes with a krye. 1587 Fleming Contn. Holinshed III. 1003/1 To hallow home cardinall Poole their countriman. 1674 N. Cox Gentl. Recreat. i. (1677) 99 Hallow in your Hounds untill they have all undertaken it. 1696 S. Sewall Diary 13 Jan. (1878) I. 419, I went to Sheaf and he hallowed over Jno. Russell again. a1713 T. Ellwood Autobiog. (1765) 265 Clapping their Hands and hallowing them on to this evil Work. 1812 Sporting Mag. XXXIX. 184 They [fox hounds] were then halloed back. 
   2. intr. To shout, in order to urge on dogs to the chase, assist combined effort, or attract attention.
   c1420 Anturs of Arth. v, The hunteres they haulen [= halwen], by hurstes and by hoes. c1440 Promp. Parv. 224/1 Halowyn, or cryyn as schypmen (P. halowen with cry), celeumo. 1525 Ld. Berners Froiss. II. lxi. [lxiv.] 209 They+halowed after them as thoughe they had ben wolues. 1567 W. Wren in Hakluyt Voy. (1589) 149 When they hallowed we hallowed also. 1612 Drayton Polyolb. xiii. 216 The shepherd him pursues, and to his dog doth halow. 1634 Milton Comus 226, I cannot halloo to my brothers. 1815 W. H. Ireland Scribbleomania 2 Though loudly the Bards all against me may halloo, I rank with the time a true chip of Apollo. 
   3. trans. To shout (something) aloud.
   ?a1400 Morte Arth. 3319 What harmes he has hente he halowes fulle sone. 1601 Shakes. Twel. N. i. v. 291 Hallow your name to the reuerberate hilles. 1676 Dryden Aurengz. v. i. 2226 In your Ear Will hallow, Rebel, Tyrant, Murtherer. 1812 H. & J. Smith Rej. Addr. ix. (1873) 82 And never halloo ‘Heads below!’ 
   Hence "hallowing vbl. n. and ppl. a.
   13+ Gaw. & Gr. Knt. 1602 There watŠ blawyng of prys in mony breme horne, HeŠe halowing on hiŠe. 1483 Cath. Angl. 172/1 An Halowynge of hundis, boema. 1569 J. Sandford tr. Agrippa's Van. Artes Pref., The hallowinge Hunter, will set his houndes and hawkes upon me. 1597 Shakes. 2 Hen. IV, i. ii. 213 Hallowing and singing of Anthemes. 1755 B. Martin Mag. Arts & Sc. 156 Making great Noises by hallowing, hooting, etc. 
Hallow, int.
Obs.   An exclamation to arouse to action, or to excite attention.
   1674 ButlerGeneva Ballad 63 Heark! How he opens with full Cry! Hallow my Hearts, beware of Rome
   obs. or dial. form of hollow a.

Why did Dumbledore have James’s Invisibility Cloak?

Note: First is my original theory and then after "Update" is my revised theory.

JK Rowling recently updated her website to include the following entry:


... which means, 'never asked question'.

Why did Dumbledore have James' invisibility cloak at the time of James' death, given that Dumbledore could make himself invisible without a cloak?

Prior to posting this I had a quick look on-line, and realised that some fans have been speculating about this question. However, nobody has ever asked me about it, and they really should have done. Just to allay the fears of the justifiably suspicious, this isn't what we in the know call 'a Mark Evans situation.'* There IS a significant - even crucial - answer."

So what is the crucial expanation?

When Harry received the Invisibility Cloak for Christmas in PS/SS, the attached note read:
“Your father left this in my possession before he died. It’s time it was returned to you. Use it well.”
We later found out Dumbledore had written the note, so James gave his Invisibility Cloak to Dumbledore before Voldemort attacked Godric’s Hollow. 
The Order had several Invisibility Cloaks at their disposal if they were taking turns guarding the Potter house. But since the Potters were under the Fidelius Charm, I don’t think they did have round-the-clock guards because as long as they stayed in the house, Voldemort wouldn’t be able to find them even if his nose was pressed against their window as Flitwick said in PA10.  Everyone except James, Lily, Wormtail, and Sirius believed Sirius was the Potters’ Secret Keeper, and it was widely believed that Sirius would die before divulging their location; moreover, Sirius said he was going into hiding himself, so the Potters would have been considered relatively safe from the point of view of the people who cared about them.
However, the Potters couldn’t leave the house, so they needed help as far as getting groceries and other necessities, especially with a baby. They would have wanted news given their situation but couldn't risk owls flying to their home.  I think James gave the Invisibility Cloak to Dumbledore to be used by whatever people were going to be helping the Potters while they were in hiding.  My guess is Dumbledore set up Arabella Figg in a house next to or very close to the Potter’s house in Godric’s Hollow (just as she had been stationed on Wisteria Drive) and that Dumbledore lent her the Cloak so she could run errands and check up on the Potters without attracting undue attention going back and forth to their house all the time.  So there is no difficulty understanding why Figg had been told where the Potters were staying, and Figg is the perfect person for that type of neighborhood watch duty since she was an original member of the Order and since none of the witches and wizards at Harry's trial at the beginning of OP knew who she was.
This would explain how Dumbledore knew about Voldemort’s attack on the Potters at Godric’s Hollow that night since neighbor Figg would have heard a disturbance and gone to listen, thereby learning basically what had happened when Voldemort was attacking the Potters inside the house. When things quieted down, Arabella went into the house far enough to see James’s dead body, assumed all the Potters had been killed, and ran back to her own house to send an owl to Dumbledore telling him what had happened.  This also explains why the person who knew what had happened didn’t assist James and Lily since Figg is a squib. 
I think it’s likely Wormtail was in hiding nearby, so Figg wouldn’t have seen him there. Wormtail could have run into the house when she left to send the owl, and he picked up Voldemort’s wand before taking off himself. 
It was shortly after Voldemort’s attack that both Hagrid and Sirius converged at the Potter house in Godric’s Hollow. Sirius had gone to check on Wormtail in his hiding place, but when he saw that Wormtail wasn’t there, he headed for the Potters and found the destroyed house.  Hagrid arrived at the same time, having been sent by Dumbledore, and as we know, Hagrid pulled baby Harry out of the smoking ruins. How did Dumbledore know what had happened? Arabella Figg sent him an owl, and we know owls travel fairly quickly because owls from the MoM, Arthur Weasley, and Sirius arrived very soon after Harry conjured a Patronus at the beginning of OP.
So my theory offers an explanation for Dumbledore’s possession of James’s Invisibility Cloak, and it’s “crucial” because it explains how Dumbledore knew what had happened that night and was able to send Hagrid so quickly.

Editing to add an explanation for how Figg could have known about the location:

Flitwick said the Secret Keeper must “choose to divulge” the location, but that doesn't mean the Secret Keeper must give the location in person or aloud.  Dumbledore was the Secret Keeper for the Order of the Phoenix's headquarters at Number Twelve Grimmauld Place.  Harry didn't learn this directly from Dumbledore; he  learned it from a note Dumbledore had written and entrusted with Alastor Mood.  So a similar situation explains how people like Dumbledore and Hagrid knew where the Potters were staying even though they didn’t know Wormtail was the Secret Keeper.

And since Sirius had engineered the switch and wanted it to work as a bluff, Sirius was probably showing people like Dumbledore and Hagrid the note indicating the location of the Potters’ house. So long as Wormtail wanted someone to know where the Potters were staying (or gave permission to tell them), Sirius would have been able to show them the note just as Moody showed Harry the note saying the Headquarters for the OotP is 12GP.  So there is no difficultly understanding how Figg could have known where the Potters were staying.  If Dumbledore asked Sirius to let her know, Sirius would only have needed to get permission from Wormtail.  And in order to maintain the bluff, Wormtail wouldn't have refused.

Update #1:

In looking carefully at the 24 hours and passages in PA, I noticed Sirius said he had "arranged" to check on Wormtail that night at his hiding place (“I’d arranged to check on Peter, make sure he was still safe"), so  Wormtail was expecting Sirius on the night of October 31and that seems to be THE reason why the attack was planned for that night.   If Sirius was expected at  Wormtail's hiding place around 11:00 PM, then Voldemort and Wormtail planned to be at Godric's Hollow at 11:00 PM.  That way Voldemort would know Sirius wasn't with the Potters when he attacked and Sirius would be expected to Apparate to Godric's Hollow  as soon as he realized Wormtail wasn't in his hiding place, and as soon as he arrived, he would be killed by Wormtail who was waiting for him outside.  That way, the WW would wake up to find the Potters and their presumed Secret Keeper dead by Voldemort's hand, a situation that would allow Wormtail to maintain his cover as a spy in the Order.  However, the curse backfired on Voldemort and Sirius flew the motorcycle instead of Apparating, so all Wormtail could do was grab the wand and figure out a way to fake his own death and frame Sirius for it.  As a commentor noted, Wormtail could have been hiding in rat form, so he didn't need an  Invisibility Cloak.

The reason this blows my original Figg theory is that Wormtail would, of course, know that Arabella had been given the Potters' location, and he would have killed her first so she wouldn't be able to interfere once Voldemort and Wormtail arrived at the Potters' house.  I don't believe Voldemort would have wanted any additonal people to know the Potters' location, and it's for that reason I don't believe he involved Snape  in his plans that evening (the hot theory is that Snape was there under James's Invisibility Cloak).  The fewer people who knew the plan, the better, just as Voldemort hadn't enlisted the help of any DE's in PS/SS when he possessed Quirrell and just as he kept the number of DE's "in the know" in GF to the barest minimum (Wormtail and Barty Crouch, Jr.).   I can think of no good reason why Voldemort would want Snape to know about the plan to attack the Potters and be given the Potters' location via Wormtail (by a method by which Snape didn't know Wormtail was the Secret Keeper), or if he did,  how it was that Snape was at Godric's Hollow that night at the time of the attack with an Invisibility Cloak, let alone James Potter's Invisibility Cloak.   Travis has posited a theory over on Sword of Gryffindor, but while it is techically plausible, I don't find it remotely likely.  If Snape had been told the Potters' location and told of the plan to attack them that night, Snape could have sent a Patronus to Dumbledore, who could have alerted the Potters by Fawkes or his own Patronus.  There just seems no remotely likely way to explain how Snape happened to have James's Invisibility Cloak that night or why Snape would have been trying to warn James instead of letting Dumbledore do that (for one thing, Snape would have to explain to James how he knew Voldemort was about to attack, and finding out Snape was a Death Eater would hardly have given James reason to trust a man who was already his enemy).

It is still possible that Arabella was monitoring the general area, heard/saw the destruction of the house, went in far enough to see James's body, and then sent an owl to Dumbledore saying she thought the Potters were all dead.  [An alternate explanation for how Dumbledore knew is that Lily, running for Harry, sent a Patronus messenger to Dumbledore saying Voldemort had found them.]  Dumbledore didn't know the Potters' location, but he would have been able to send Fawkes to the site instantly since Hedwig was able to deliver letters to Ron, Hermione, and Sirius when they were all at 12 Grimmauld Place under the Fidelius Charm.  Fawkes is able to communicate enough for Dumbledore to have ascertained that Harry had survived.  Hagrid could have been dispatched to Godric's Hollow by portkey with a broom to fly Harry to Little Whinging and not seen Arabella since she would have returned to her house to await instructions.  So it is possible that Arabella was generally monitoring the neighborhood using James's Invisibility Cloak and had informed Dumbledore of the attack and the destruction of the house without realizing the baby had survived.

The Figg-as-neighborhood-monitor isn't a dramatic theory, but it would explain why Dumbledore had been given James's Invisibility Cloak before being killed and it's a significant--even crucial--explanation because it was the way Dumbledore found out about the attack on the Potters so quickly and was able to get Hagrid there before anyone else.  Nevertheless, it still isn't a satisfying theory because it seems to me that if Figg had been able to tell Dumbledore that the house had been destroyed, Dumbledore should have known that the Fidelius Charm was broken.  Hagrid hadn't even known that Sirius was the Potters' Secret Keeper, and Dumbledore sent him to get Harry out of the ruins, so Hagrid was able to find the house even without having been told the location before the attack on the Potters.  So why would Dumbledore have sent Fawkes instead of Apparating out of the castle with Fawkes as he had done in OP when Umbridge and Fudge were about to arrest him over Dumbledore's Army?  And although Dumbledore trusted Hagrid with his life, Hagrid couldn't Apparate legally even if he had been given private lessons (he had been expelled from school at age 13, so he wasn't supposed to do any magic), and surely saving this baby was uppermost in Dumbledore's mind.  So why didn't Dumbledore take five minutes to get Harry and return to Hogwarts so he could complete his preparations for the spell on the Dursleys and do whatever else he needed to do with the baby safe at Hogwarts?  Why not send McGonagall to Apparate to get the baby?  Dumbledore wasn't expecting Hagrid to show up at the Dursleys until nearly midnight on November 1, so he must have believed Hagrid was taking very slow transportation (like a broom) from quite a distance.  

The "24 hours" is a nightmare. There better be a good explanation coming!
Monday night, October 31, 1981
Sometime during the night of Monday, October 31, 1981, Voldemort showed up at Godric’s Hollow, killed the Potters and was destroyed by the rebounding curse, which also destroyed the house. Harry was in his crib, and James told Lily to get Harry and run while he faced Voldemort. They could have had an intruder detector like Slughorn’s that alerted them but didn’t give them enough time to get out (that would be true if Voldemort Apparated close to the house).
On the same night, Sirius said he had gone, as arranged, to check on Wormtail in his hiding place, discovered him missing, got worried, and headed straight for Godric’s Hollow on his flying motorcycle. Notably, Sirius said, “I’d arranged to check on Peter, make sure he was still safe,” so if Wormtail was expecting Sirius around a particular time, that seems to be THE reason why the attack was planned for that night—because Sirius had made the arrangements, Voldemort and Wormtail could set Sirius up without making him suspicious.
We don’t know the distance between Wormtail’s hiding place and Godric’s Hollow or how fast the motorcycle travels. I’ll guess not extraordinarily fast from the hints in PS1, so maybe it's as fast as the Ford Anglia, which was the speed of the Hogwart's Express. So either Wormtail’s hiding place was not far from the Potter house and Sirius got there fairly quickly or it took Sirius a long time to get to Godric’s Hollow and we have to wonder why he took the pokey motorcycle instead of Apparating given that he was worried. For that matter, when Sirius didn’t find Wormtail, why didn’t he send his patronus to James and Lily to ask if they were okay?
Between Monday night, October 31 and Tuesday morning, November 1
On his ride to work at 8:30-9:00 AM, Vernon noticed witches and wizards on the sidewalks in groups whispering together, so not only had McGonagall heard the rumors about Voldemort's defeat and Harry's survival, the entire WW was talking about it.  This is more confirmation that Dumbledore had heard the news between late night October 31 and early morning November 1. 
At 8:30 AM on Tuesday, November 1, McGonagall (in cat form) was on the corner of Privet Drive looking at a map when Vernon spotted her. She was there to wait for Dumbledore because Hagrid told her that’s where Dumbledore was going to be. So Hagrid told McGonagall (presumably at Hogwarts) sometime between late night October 31 and 8:30 AM November 1 that Dumbledore was going to 4 Privet Drive that day. This had to be before Hagrid left for Godric’s Hollow because he didn’t have Harry. 

We don’t know what time Hagrid spoke to McGonagall or where Dumbledore was when they spoke. Maybe Dumbledore was on his way out when he told Hagrid to go to Godric’s Hollow to get Harry or maybe he told Hagrid he didn’t want to be disturbed and would meet Hagrid and Harry later at 4 Privet Drive, Little Whinging. Perhaps Dumbledore was checking information related to the blood magic he was about to invoke on the Dursleys and/or writing the letter to them about what had happened and/or notifying the Order, etc. Perhaps he went to Privet Drive to set up the charm, which could be an “immensely complex spell” just like the Fidelius Charm. As Travis noted, by the time Dumbledore did appear at the Dursleys, the charm had been set up; he only needed Petunia to take in Harry to seal it.
Between Tuesday 8:30 AM, November 1 and early Wednesday morning, November 2
McGonagall waited at 4 Privet Drive for nearly 16 hours before Dumbledore arrived around midnight. They talked for a bit, and Dumbledore confirmed the rumors she’d heard that James and Lily were dead, Harry survived, and Voldemort’s powers had been broken. She didn’t say where she heard the rumors—at school or somewhere else (I assume she heard the rumors from Hagrid, but that’s not confirmed by the text). Then Dumbledore looked at his watch and said Hagrid was late. Hagrid showed up a few minutes later with Harry, which was very early on Wednesday, November 2.
Given Hagrid’s route over Bristol on his way to Little Whinging (which is near London) and the fact that baby Harry fell asleep over Bristol, it initially seemed likeliest that Godric’s Hollow is in southern Wales. However, it could be in southern Ireland or even further out in the Altantic and still work with the pass over Bristol, especially since Hagrid thought Sirius had wanted baby Harry in order to throw him overboard "halfway out to sea," which certainly indicates part of the journey was over water.  Ireland would double the length of the trip and account for more time. But that means either Wormtail lived in southern Ireland in order for Sirius to reach Godric’s Hollow fairly quickly by flying motorcycle or else Sirius inexplicably spent hours getting to the Potter house by motorcycle even though he thought they might be in trouble (and that would also mean it was hours after the attack before Hagrid and Sirius got there).
Whatever the answer, none of the Invisibilty Cloak theories proposed so far explains to my satisfaction when and how Dumbledore found out what happened at Godric's Hollow and how he knew Harry had survived even before he sent Hagrid to get Harry.


Update #2:

Rowling updated her website today (9/29/06).
Under "Rumours"
Rumor: Snape was hiding under the Invisibility Cloak on the night the Potters died.
Answer: No, he wasn’t.

Nagini as Horcrux

The argument for Nagini as the sixth Horcrux
(Tweaked on 9-9 in response to comments)

In an interview with The Leaky Cauldron and MuggleNet in July 2005, Rowling said,
“Dumbledore's guesses are never very far wide of the mark. I don't want to give too much away here, but Dumbledore says, ‘There are four out there, you've got to get rid of four, and then you go for Voldemort.’ So that's where he is, and that's what he's got to do. . . . . It's a huge order. But Dumbledore has given him some pretty valuable clues and Harry, also, in the course of previous six books has amassed more knowledge than he realizes. That's all I am going to say.
So what were Dumbledore’s guesses?
"...I think I know what the sixth Horcrux is.  I wonder what you will say when I confess that I have been curious for a while about the behavior of the snake, Nagini?”
“The snake? said Harry, startled. “You can use animals as Horcruxes?”
“Well, it is inadvisable to do so,” said Dumbledore, “because to confide a part of your soul to something that can think and move for itself is obviously a very risky business. However, if my calculations are correct, Voldemort was still at least one Horcrux short of his goal of six when he entered your parents’ house with the intention of killing you.”
“He seems to have reserved the process of making Horcruxes for particularly significant deaths. You would certainly have been that. He believed that in killing you, he was destroying the danger the prophesy had outlined. He believed he was making himself invincible. I am sure that he was intending to make his final Horcrux with your death.
“As we know, he failed.  After an interval of some years, however, he used Nagini to kill an old Muggle man, and it might then have occurred to him to turn her into his last Horcrux.  She underlines the Slytherin connection, which enhances Lord Voldemort's mystique; I think he is perhaps as fond of her as he can be of anything; he certain likes to keep her close, and he seems to have an unusual amount of control over her, even for a Parselmouth."
“So,” said Harry, “the diary’s gone, the ring’s gone. The cup, the locket, and the snake are still intact, and you think there might be a Horcrux that once was something of Ravenclaw’s or Gryffindor’s?”
“An admirably succinct and accurate summary, yes,” said Dumbledore, bowing his head.[HBP-23]
Before getting into the arguments for Nagini as Horcrux, an explanation must be given for Dumbledore’s assumption that Voldemort had used Nagini to kill Frank Bryce since we know Babymort cast an AK to kill Frank. First, Dumbledore was drawing a parallel to young Tom Riddle’s use of Slytherin’s basilisk to kill Moaning Myrtle, and second, Dumbledore knew from reading Muggle newspapers that Frank Bryce had disappeared without a trace (GF30), so Dumbledore may have assumed Nagini killed on Voldemort’s orders and ate Frank Bryce’s body, which was not a crazy assumption given that Voldemort planned to feed Harry’s body to Nagini after the rebirthing ceremony:
“Nagini,” said the cold voice, “you are out of luck. I will not be feeding Wormtail to you, after all . . . but never mind, never mind . . . there is still Harry Potter . . . .” (GF29)
We got our initial information about Horcruxes (“wickedest of magical inventions”) from Slughorn, who said a Horcrux is “an object in which a person has concealed part of their soul.”  To make a Horcrux, the soul needs to be split first by a supreme act of evil—murder—so that a torn portion could be encased in the object. “Then, even if one’s body is attacked or destroyed, one cannot die, for part of the soul becomes earthbound and undamaged.” (HBP23) Slughorn did not know the spell used to encase the torn soul fragment in the object.
We can expect that Dumbledore, who was hunting Voldemort’s Horcruxes, had learned all he could on the subject of making and destroying them, and we got more information about making Horcruxes from Dumbledore’s assumption that Voldemort had used Nagini to kill Frank Bryce and afterwards thought to turn her into a Horcrux. His supposition tells us: 1) the murder is what counts, not the method used to kill (killing curse, lethal poison, etc.), 2) it doesn’t matter whether the murderer killed directly or used a proxy he was controlling (Slytherin’s basilisk, Nagini), 3) the murderer doesn’t even need to be considering making a Horcrux at the time of the murder to be able to make a Horcrux from that murder after, and 4) the murder comes before the Horcrux is made rather than being an internal part of the Horcrux-making process.  Since Voldemort was planning to use Harry’s death to make his final Horcrux, canon indicates Voldemort needed to kill Harry before performing the Horcrux ritual, and since the killing curse backfired and destroyed Voldemort’s body, he had no opportunity to make a Horcrux at Godric’s Hollow. Moreover, I suspect that since Horcruxes are the “wickedest of magical inventions,” they are created not with a flick of the wand and a word or two, but involve dark ritualist magic of the sort used for Voldemort’s rebirthing in the graveyard. 
That Voldemort would make a Horcrux out of Nagini didn't make a lot of sense to me at first given that he wanted to use distinguished, durable vessels worthy of his soul fragments, so Nagini wouldn’t have been his choice if other options were available, but perhaps he felt vulnerable at the beginning of Goblet of Fire and Nagini was a good choice given his circumstances and needs at that time.
Dumbledore said it’s not advisable to place a Horcrux in something that can move and think for itself, so under normal circumstances, Voldemort would not have chosen a living thing, but at the time he turned Nagini into a Horcrux, his circumstances weren’t normal. Voldemort is extremely independent (recall that even at age 11, he bragged about roaming London on his own, and he didn’t want Dumbledore’s help to find Diagon Alley and buy his school things), yet during Goblet of Fire when Babymort was newly back in the UK with Wormtail, he was vulnerable and dependent. His Legilimency skills told him Wormtail was repulsed by him and found the round-the-clock care he needed onerous.  
“And so you volunteer to go and fetch me a substitute? I wonder . . . perhaps the task of nursing me has become wearisome for you, Wormtail? Could this suggestion of abandoning the plan be nothing more than an attempt to desert me?
“My Lord! I—I have no to wish to leave you, none at all—“
“Do not lie to me!” hissed the second voice. “I can always tell, Wormtail! You are regretting that you ever returned to me. I revolt you. I see you flinch when you look at me, feel you shudder when you touch me . . . “
“No! My devotion to your Lordship—“
“Your devotion is nothing more than cowardice. You would not be here if you had anywhere else to go. How am I to survive without you, when I need feeding every few hours? Who is to milk Nagini?”
“But you seem so much stronger, My Lord—“
“Liar,” breathed the second voice. “I am no stronger, and few days alone would be enough to rob me of the little health I have regained under your clumsy care.” (GF1)
What was Babymort’s condition?
“It was as though Wormtail had flipped over a stone and revealed something ugly, slimy, and blind—but worse, a hundred times worse. The thing Wormtail had been carrying had the shape of a crouched human child, except that Harry had never seen anything less like a child. It was hairless and scaly-looking, a dark, raw, reddish black. Its arms and legs were thin and feeble, and its face—no child ever had a face like that—flat and snakelike, with gleaming red eyes.
The thing was almost helpless: it raised its thin arms, put them around Wormtail’s neck, and Wormtail lifted it. As he did so, his hood fell back, and Harry saw the look of revulsion on Wormtail’s weak, pale face in the firelight as he carried the creature to the rim of the cauldron. (GF32)
Voldemort knew it would be nearly a year before the ritual to restore him to a full body with Harry’s blood would be performed, and until then, he would be utterly dependent.  Wormtail wasn’t happy with the situation, and Babymort knew it.  So he may have decided to make a Horcrux out of Nagini for practical reasons. He would have more control over Nagini if she contained part of his soul, so he would be able to use her to keep Wormtail in line. If Wormtail did abandon him, Nagini would be able to act as his scout and messenger to find another Death Eater and lead him or her to the Riddle house. Voldemort clearly didn't want his Death Eaters to see him as Babymort, which is why he and Wormtail made no contact with any all year except for the necessary contact with Barty Crouch, Jr. Voldemort didn’t summon them until he was back in a full body with full powers. 
One of the reasons I believe Voldemort wanted founders’ relics is that they often, if not always, have special magical powers. Hepzibah Smith said the Hufflepuff Cup and Slytherin Locket had “all sorts of powers” and we know Gryffindor’s Sorting Hat does. So where does Nagini fit in? In Hindu and Buddhist tradition, Nagas are a race of semi-divine snakes with great powers, and a female Naga is called a Nagini. Although we have never been told what kind of snake Nagini is, Nagas are traditionally depicted as large cobra-like snakes, and Nagini in GF1 was described as having an “ugly triangular head.” Nagas have an affinity for water, carry the Elixir of Life, and symbolize both fertility and immortality. In Malaysian tradition, the natural enemy of the Naga is a phoenix.
So Nagini’s name tells us she isn’t just a big snake. Rowling has tied all the traditional Naga associations to Nagini. Voldemort is a Slytherin by blood and house (water element). He used Nagini’s venom to keep himself alive during Goblet of Fire (Elixir of Life). Babymort’s description as being like a human child with a hairless, reddish-black, scaly body and flat snake-like face along with the use of the verb “milked” to collect Nagini’s venom suggest Nagini was used to get Vapormort into a rudimentary physical form (fertility); this last association is deliberate since there is a strong “mother” pattern in Goblet of Fire (Draco insulted Molly, Harry responded by insulting Narcissa, Mrs. Crouch died in Azkaban to free Barty, Jr., Molly and Bill stood in for Harry’s family, the dragons were brooding mothers, Charlie wrote to "Mum" after the first task to tell her Harry was fine, Voldemort spoke of Merope and Lily in the graveyard, Lily's shade spoke to Harry during the Priori Incantatem spell, Molly embraced Harry in the hospital, and for the first time in his experience, he was hugged “as though by a mother,” etc.). So Voldemort's use of Nagini to thwart death by making her into a Horcrux would complete the traditional Naga associations (immortality).

Moreover, in "all mythological language the snake is also an emblem of immortality. Its endless representation with its tail in its mouth (Ouroboros), and the constant renewal of its skin and vigor, enliven the symbols of continued youth and eternity (Soror Ourania, "Thelemix and Therion Rising"). The Healers at St. Mungo's had a hard time closing Arthur’s wounds because Nagini’s venom was so extraordinary, suggesting an unusual snake. If Nagini is a magical creature with special powers who was the means to Voldemort's mini-rebirthing as appears, he would have reason to find her a significant vessel for his soul fragment. And she may even be a very long-lived magical snake, just as Slytherin’s basilisk was.
Another reason Voldemort may have decided to use Nagini as a Horcrux in GF1 is that it gave Voldemort his set of seven Horcruxes, so he would have the magical power of seven during a time when he was vulnerable and preparing to kill the very boy who had somehow defeated him 13 years earlier (Voldemort didn’t know then that the diary had been destroyed).  He might have used a more distinguished object even then (especially if he left his intended vessel behind at Godric’s Hollow), but then he would have had to involve Wormtail to get the object for him, and that would make Wormtail suspicious. Voldemort is not likely to have entrusted Wormtail with Horcrux information, but he would have been able to turn Nagini into a Horcrux using Frank Bryce’s murder without Wormtail's being any the wiser. And since Voldemort and Nagini communicate in Parseltongue, Wormtail would not become suspicious that Voldemort seemed to be exercising greater control over Nagini than previously or would not know the reason for Voldemort's greater control.  
Many people believe Dumbledore mentioned Nagini only as a hint to Harry that Harry himself was carrying a part of Voldemort’s soul in him, but that doesn’t work for me. Dumbledore learned his lesson about withholding vital information from Harry because Sirius died at the end of Order of the Phoenix and Harry would have died if not for Dumbledore’s nick-of-time intervention.  From that, Dumbledore learned that withholding unpleasant news from Harry led to a disaster rather than averted one, so he wouldn’t make that mistake again. Moreover, for Dumbledore to suspect Harry has a piece of Voldemort’s soul in him but to tell Harry that Nagini is the likely Horcrux (and give several reasons why Voldemort would turn her into one) would be far worse than merely withholding information; it would be tantamount to setting up Harry’s failure by sending him in the wrong direction and potentially leaving him vulnerable to another of Voldemort’s traps.
Rowling has given us passages indicating to us that Dumbledore’s confident hunch about Nagini's being a Horcrux was not amiss. Consider how much control Voldemort had over Nagini while possessing her when Arthur Weasley was attacked outside the door to the Department of Mysteries in Order of the Phoenix. Nagini had to travel from Little Hangleton to London and then negotiate her way around the Ministry of Magic to get to the right floor and Department of Mysteries, and then return to Little Hangleton after attacking Arthur. 
During the attack, Harry dreamed he was inside Nagini:
“The dream changed . . . .
His body felt smooth, powerful, and flexible. He was gliding between shining metal bars, across, cold stone. . . . He was flat against the floor, sliding along on his belly. . . . It was dark, yet he could see objects around him shimmering in strange, vibrant colors. . . . He was turning his head. . . . At first glance, the corridor was empty . . . but no . . . a man was sitting on the floor ahead, his chin drooping onto his chest, his outline gleaming in the dark. . . .
Harry put out his tongue. . . . He tested the man’s scent on the air. . . . He was alive but drowsing . . .sitting in front of a door at the end of the corridor . . .
Harry longed to bite the man . . .but he must master the impulse . . . he had more important work to do . . . .
But the man was stirring . . . a silvery cloak fell from his legs as he jumped to his feet; and Harry saw his vibrant, blurred outline towering above him, saw a wand withdrawn from a belt. . . .He had no choice. . . . He reared high from the floor and struck once, twice, three times, plunging his fangs deeply into the man’s flesh, feeling his ribs splinter beneath his jaws, feeling the warm gush of blood. . . . .
The man was yelling in pain . . . then he fell silent. . . . He slumped backward against the wall. . . . Blood was splattering onto the floor. . . .
His forehead hurt terribly. . . . It was aching fit to burst. . . . (OP21)
On the night Harry saw Arthur attacked by Nagini, Dumbledore ran a test with one of his little whirring, silver, smoky instruments. We don’t know what nonverbal command Dumbledore gave to the instrument when he tapped it with wand, but a after a few seconds, a snake took form out of the smoke. When Dumbledore said, “But it essence divided?” the smoky snake divided into two snakes. I don’t know for sure what Dumbledore meant by “in essence divided,” but he surely was performing an experiment directly related to Harry’s dream about the snake attack. 
"Dumbledore now swooped down upon one of the fragile silver instruments whose function Harry had never known, carried it over to his desk, sat down facing them again, and tapped it gently with the tip of his wand.
The instruments tinkled into life at once with rhythmic clinking noises. Tiny puffs of pale green smoke issued from the miniscule silver tube at the top. Dumbledore watched the smoke closely, his brow furrowed, and after a few seconds, the tiny puffs became a steady stream of smoke that thickened and coiled in the air. . . . A serpent's head grew out of the end of it, opening its mouth wide. Harry wondered whether the instrument was confirming his story: He looked eagerly at Dumbledore for a sign that he was right, but Dumbledore did not look up.

"Naturally, naturally," murmured Dumbledore apparently to himself, still observing the stream of smoke without the slightest sign of surprise. "But in essence divided?"

Harry could make neither head nor tail of this question. The smoke serpent, however, split itself instantly into two snakes, both coiling and undulating in the dark air. With a look of grim satisfaction, Dumbledore gave the instrument another gentle tap with his wand: The clinking noise slowed and died, and the smoke serpents grew faint, became a formless haze, and vanished."
As Snape later told Harry, “You seem to have visited the snake’s mind because that was where the Dark Lord was at that particular moment” . . . “He was possessing the snake at the time and so you dreamed that you were inside it too. . . . “ (OP24)  We don’t know what command Dumbledore gave the silver instrument, but I take this experiment as one of Dumbledore’s reasons for suspecting Voldemort may have turned Nagini into a Horcrux; it may have confirmed the possibility or likelihood of it, since Dumbledore was not 100% certain that Nagini was a Horcrux. I do believe that following Harry’s report and the experiment, Snape was asked to keep an eye on the interaction between Nagini and Voldemort and report back to Dumbledore. We do not know when Voldemort obtained Nagini, but Dumbledore knows the snake’s name, knows Voldemort likes to keep her close, and knows Voldemort has an unusual amount of control over her, even for a Parselmouth.
How different was the snake dream from Harry’s owl dream at the end of Goblet of Fire. In the owl dream, the episode with Barty Crouch, Sr.'s stumbling out of the Forbidden Forest and subsequently disappearing had happened a couple of days earlier.  Harry was sitting in Divination class when he fell asleep and began to dream:
“He was riding on the back of an eagle owl, soaring through the clear blue sky toward an old, ivy-covered house set high on a hillside. Lower and lower they flew, the wind blowing pleasantly in Harry’s face, until they reached a dark and broken window in the upper story of the house and entered. Now they were flying along a gloomy passageway, to a room at the very end . . . through the door they went, into a dark room whose windows were boarded up. . . .
Harry had left the owl’s back . . .he was watching, now, as it fluttered across the room, into a chair with its back to him. . . . There were two dark shapes on the floor beside the chair . . .both of them were stirring. . . .
One was a huge snake . . .the other was a man . . .a short, balding man, a man with watery eyes and a pointed nose . . .he was wheezing and sobbing on the hearth rug. . . .
“You are in luck, Wormtail,” said a cold, high-pitched voice from the depths of the chair in which the owl had landed. “You are very fortunate indeed. Your blunder has not ruined everything. He is dead.” (GF29)
Harry awoke from the dream with his scar burning from Voldemort’s torture of Wormtail, but what strikes me is that Harry dreamt he was the snake in Order of the Phoenix whereas he dreamt he was merely flying next to the owl in the Goblet of Fire dream.  In the snake dream, Voldemort was possessing Nagini, so Harry was mentally inside Nagini’s body along with Voldemort’s mind, whereas in the owl dream, Harry was flying alongside the bird because Voldemort’s mind was only dwelling on the owl that would bring news of Barty Crouch, Sr.’s escape from Wormtail, not possessing the owl. In both dreams, Harry’s scar connection was to Voldemort’s mind. Dumbledore told Harry at the end of Order of the Phoenix that on the night of the snake attack on Arthur, Harry had “entered so far into his mind and thoughts that he sensed your presence.” (OP7)
And indeed, on her website, Rowling has described the scar as forging a mind-to-mind connection between Harry and Voldemort:
“In choosing which boy to murder, he was also (without realising it) choosing which boy to anoint as the Chosen One – to give him tools no other wizard possessed – the scar and the ability it conferred, a magical window into Voldemort's mind.” 
Rowling appears to me to be working with a tripartite anthropology (body + mind + soul) rather than a bipartite anthropology (body + soul). From what I’ve read in the six books to date, the soul is an essence that enables self-awareness, but it is separate from the conscious mind/brain.  A big hint came in Prisoner of Azkaban when Lupin described what happens when a dementor’s kiss sucks the soul out of a person. The victim's brain could be working, but he or she would have no memories because the soul enables self-awareness.  Clearly there must be another animating force keeping the body alive, so the bipartite model doesn't fit:
“You can exist without your soul, you know, as long as your brain and heart are still working. But you'll have no sense of self anymore, no memory, no ... anything. There's no chance at all of recovery. You'll just -- exist. As an empty shell. And your soul is gone forever ... lost." (PA12)
In Half-blood Prince, Dumbledore distinguished between Voldemort’s soul on one hand and his mind/powers on the other, and it's a curious statement given that Vapormort was without a physical brain for 13 years, so he must be referring to the conscious mind of Vapormort's spectral self during those years of exile in Albania:
 . . . “Without his Hocruxes, Voldemort will be a mortal man with a maimed and diminished soul. Never forget, though, that while his soul may be damaged beyond repair, his brain and his magical powers remain intact  (HBP23)
So it seems Dumbledore was correct when he told Harry in Chamber of Secrets that Voldemort had unintentionally transferred some of his powers into Harry:
“You can speak Parseltongue, Harry,” said Dumbledore calmly, “because Lord Voldemort—who is the last remaining ancestor of Salazar Slytherin—can speak Parseltongue. Unless I’m much mistaken, he transferred some of his own powers to you the night he gave you that scar. Not something he intended to do, I’m sure. . . . “
‘”Voldemort put a bit of himself in me?” Harry said, thunderstruck.
“It certainly seems so.”
“So I should be in Slytherin,” Harry said, looking desperately into Dumbledore’s face. “The Sorting Hat could see Slytherin’s power in me, and it—“ (CS18)
Some of Slytherin's/Voldemort’s power had been transferred into Harry when the killing curse backfired, not some of Voldemort’s soul.  There are two clues that support the transfer of mind/powers to Harry.  The brain that attacked Ron in the Department of Mysteries left “thought scars” on Ron's arms, and according to Madam Pomfrey, "thoughts could leave deeper scarring than almost anything else.” (OP38).  The Sorting Hat is the other clue since Rowling has unequivocally stated it is not a Horcrux, yet the Sorting Hat is able to communicate telepathically with the students wearing it and it looks into their minds to assess their current and potential abilities (intelligence, magical talent, ambition, fair-mindedness, etc.). Most importantly, we know from the Hat that it's able to do those things because "the founders put some brains in me."  (GF12)
Moreover, the killing curse didn’t work against Harry as Voldemort expected because of the “ancient magic” protecting Harry invoked by Lily’s sacrificial death, and that’s a powerful reason for me to reject Harrycrux or Scarcrux theories. It was ancient protective magic invoked because she loved Harry so much she chose to die to protect him even when given the chance to live. So thematically, it just doesn’t work that Lily’s sacrifice and the magical protection her death imparted to Harry turned her baby into the “wickedest of magical inventions,” even accidentally. However, the power transfer and mind-to-mind scar connection are consistent with that ancient protective magic because Harry now has tools no other wizard possesses, tools that will enable him to vanquish the Dark Lord per the prophesy.  Harry has been marked as Voldemort’s equal because he shares some of Voldemort’s unique powers and because the scar gives him a magical window into Voldemort’s mind as Dumbledore and Rowling have stated.  
These tools and powers are neutral, not evil, as we've seen: Harry's ability to speak Parseltongue led to his freeing the boa at the zoo, saving Justin from a snake attack during the dueling match, and opening the Chamber of Secrets to save Ginny and defeat Diarymort.  As Dumbledore said, Parseltongue is also a gift found among the great and the good. It's true that Harry has entertained thoughts of torturing Severus Snape, but I think one of the reasons Rowling showed us James’s and Sirius’s dark side is so we would not assume Harry's own temptations and occasional horrendous behavior are a consequence of the powers transferred to him at Godric's Hollow. I for one can imagine James daydreaming about torturing Snape.  Sirius set Snape up to be killed or become a werewolf when they were only 16 years old.  And we know James and Sirius weren't Voldemort's Horcruxes.
So while these arguments do not prove Nagini is a Horcrux and while this is not an exhaustive rebuttal of Harrycrux and Scarcrux theories, I do believe canon evidence for Nagini as the sixth Horcrux is far superior to arguments that Harry is an accidental Horcrux.  While Dumbledore was not 100% sure of Nagini, he was confident enough to specifically name her and give reasons why Voldemort would have turned her into one. Moreover, Nagini as the sixth Horcrux is consistent with Rowling’s comment that Dumbledore’s guesses are never very far wide of the mark. Travis Prinzi (, who is not convinced that Nagini is a Horcrux (see comments and his website) argues that 'not very far wide of the mark' is not the same as 'always on the mark,' and that’s a fair point.  But I believe the wiggle room is in the mystery Horcrux: “and you think there might be a Horcrux that once was something of Ravenclaw’s or Gryffindor’s?”  
My theory is that the mystery Horcrux is not a true founder's relic like Slytherin’s locket, but is a founder family heirloom like the Peverell ring, which would make “a Horcrux that once was something of Ravenclaw’s or Gryffindor’s” slightly off the mark. (  Since Dumbledore’s description of the mystery Horcrux was vague to begin with and since the trio have the example of the Peverell ring to guide them, the "slightly off the mark" description of the mystery Horcrux isn’t dangerously misleading. Harrycrux or Scarcrux would be very far off the mark relative to Dumbledore's list.  However, I do agree with Travis that Rowling has likely written the series to date in a way that readers will wonder if a part of Voldemort's soul was transferred into Harry at Godric's Hollow; she does love the game, but I think canon evidence is against Harrycrux or Scarcrux.
A final reason why Nagini is probably the sixth Horcrux is that this is a fabulous plot set-up for Harry’s ability to speak Parseltongue. After all, both Harry and Voldemort speak Parseltongue, and it’s a key way in which Voldemort marked Harry as his equal. We haven’t seen Harry use that ability since Chamber of Secrets, and while it was the means by which Harry opened the Chamber, we didn’t see Harry attempt to speak Parseltongue to the basilisk, and we didn’t see Harry attempt to speak Parseltongue to Nagini in the graveyard. We will most definitely see him speak Parseltongue to Nagini and Voldemort in Book 7, and how much more dramatic will it be if Nagini is Voldemort’s last remaining hope for immortality?
By the time of their final confrontation, I expect Voldemort will know Harry has destroyed his Horcruxes other than Nagini, yet he may feel secure with Nagini as a Horcrux since he would not expect anyone to guess he had made a Horcrux out of an animal (which is why Harry's dream of the attack on Arthur was so important to Dumbledore's Horcrux guesses).  Voldemort keeps Nagini close, so it’s likely that Harry won’t meet up with Nagini until the final face-off with Voldemort. 
I’ve been convinced by arguments that Harry will not personally use the Avada Kedavr to kill Voldemort. We know their wands won’t work properly against each other, Snape warned Harry away from Unforgivable Curses and instead "told him" to practice Occlumency and non-verbal spells, and most importantly, I don’t think Rowling would want Harry to use the killing curse, even to destroy Voldemort.
It will certainly be dramatic when both Voldemort and Harry attempt to control Nagini by speaking Parseltongue to her, and I can see a replay of the graveyard scene when just as Harry’s powers were able to move the bead of light into Voldemort’s wand to produce the Priori Incantatem effect, so Harry’s powers will be greater than Voldemort’s in controlling Nagini when she is not being possessed by Voldemort. I’m wondering if Voldemort will possess Nagini as a way to attack Harry and reassert control. My reason for speculating so is that I’ve noticed traces of Milton’s Paradise Lost in the HP series, especially in Voldemort’s increasingly snake-like appearance and in Voldemort’s “stupidly good” offer to let Lily live (a parallel to Satan's "stupidly good" moment when he saw Eve), and it’s occurred to me that just as Satan is literally turned into a snake at the end of Paradise Lost, Voldemort may take possession of Nagini and literally become a snake before Harry finally vanquishes him.

The Avada Kedavra on the Astronomy Tower

[This post is an expansion of the first section of an essay arguing the Stoppered Death theory.  I needed more room over there to describe the background to that theory, so I moved the AK evidence here and vastly expanded it.  Read about the Stoppered Death theory here:]

The Avada Kedavra Snape Cast at Dumbledore was Real and Instantly Ended Dumbledore's Time Amongst the Living

A challenge to the arguments that Snape did not cast a real AK at Dumbledore on the Tower or that he did yet Dumbledore did not die from the killing curse but rather from the fall to the ground.
The arguments:
  • Snape didn’t hate Dumbledore, so his AK wouldn’t have been able to kill him
  • The AK didn't blast Frank Bryce into the air, so it shouldn't have with Dumbledore
  • Dumbledore’s eyes were closed, but the eyes of the other AK victims were open
  • Dumbledore’s body was suspended mid-air for a split second, so it wasn’t an AK
  • Harry wasn’t immediately released from the body-bind when the AK hit Dumbledore
  • Dumbledore was holding a magical shield to his chest that blocked the AK
  • Snape simultaneously cast a non-verbal spell, and the non-verbal trumped the AK
  • There was a trickle of blood on Dumbledore’s dead face, and only living bodies bleed


How could Snape AK Dumbledore if he didn’t hate Dumbledore?
Two things are required to pull off an Unforgivable Curse: volition (the intent of the caster to cause the outcome—pain, control, or death) and sufficient magical power. Neither is dependent on the personal feelings of the curse-caster toward the target of the curse.
Fake Moody said an AK needed a "powerful bit of magic behind it," but he didn’t say the caster needed to hate the victim, and indeed it’s not likely that Death Eaters who cast Unforgivable Curses know most of their victims well enough to have developed personal feelings toward them. Certainly Fake Moody didn’t hate the spider he AK’d in class, and Bellatrix didn’t even know what she was casting the AK at when she killed the fox in HBP2 (“Just a fox" . . .”I thought perhaps an Auror.”).
In OP, Bellatrix said Harry's Cruciatus Curse against her did not cause pain because Harry didn't have the intent to cause pain, but intent is not dependent on the curse-caster’s personal feelings toward the victim. When Harry tried to Crucio Bellatrix, we read,
"Hatred rose in Harry such as he had never known before. He flung himself out from behind the fountain and bellowed, "Crucio!"
If hatred were the key to casting the Cruciatus Curse, then Harry should have caused unbearable pain to Bellatrix since he hated her and expected the spell to cause pain to her. But he didn’t cause pain because his hatred of Bellatrix was not “powering” the Unforgivable Curse.
In HBP1, we learned that Herbert Chorley, the Muggle Junior Minister, was impersonating a duck and had attempted to strangle three Healers at St. Mungo’s because of a “poorly performed Imperius Curse,” which means the person who attempted to Imperius Chorley either didn’t have the proper volition or sufficient magical power to it off. All through HBP, Draco was shown in a weakened state: his health was suffering, he wasn't keeping up with his homework, and he was confiding in and crying to Moaning Myrtle about a job he couldn’t do. Draco may possess the magical power needed to pull off an Unforgivable Curse, and given the pressure he was under from Voldemort, he certainly would have wanted to Imperius Rosmerta to help him, but during HBP, he didn't have the strength of mind to hold Rosmerta under the Imperius Curse (so Bellatrix was doing it, I think).
Moments after casting the AK at Dumbledore, Snape was confronted by Harry on the castle grounds; Harry attempted to cast the Cruciatus Curse on Snape, who repeatedly blocked Harry’s attempts and then restated the requirements to cast an Unforgivable Curse:
"No Unforgivable Curses from you, Potter!” he shouted over the rushing of the flames, Hagrid’s yells, and the wild yelping of the trapped Fang. “You haven’t got the nerve or the ability—" 
Snape knew Harry hated him at that moment, but it wasn’t emotion Snape referred to as a requirement of casting the curse; rather, he was talking about volition (nerve) and magical power (ability). Even if Snape didn’t want to end Dumbledore’s life, he still would have been able to surmount his personal feelings to cast the curse.
Dr. Ronald Glasser, a doctor stationed in Japan during the Viet Nam conflict, in 1971 wrote 365 Days, a series of documentary sketches about American soldiers, medics, helicopter pilots, Vietnamese civilians, etc. It’s a wrenching book (still in print), and one of the most difficult chapters describes the suffering endured by the soldiers in the Army hospital burn ward where the worse cases were treated. I read the book years ago, but I haven’t forgotten the stories of severely burned soldiers who had to endure frequent treatments of hydrotherapy and mechanical debridement (scraping away of burned and necrotic tissue to reveal raw wounds and open nerves). The soldiers couldn’t be given high enough doses of narcotics to dull the pain for fear of addiction over the months of debriding treatments, and Dr. Glasser recorded the horror of the sessions as the soldiers screamed and sobbed and begged the medical personnel to stop. The doctors, nurses, and technicians had to steel themselves as much as the patients did for these treatments, knowing it was the only option that offered hope. 
Severus Snape, able to both wound and heal, is a man who would have been able to perform the AK against his friend and mentor Albus Dumbledore in that situation. Neither wanted circumstances to fall out the way they did, but both knew Snape had to cast the AK because it was the only option that offered hope given Dumbledore’s condition and the need to preserve Snape to help Harry vanquish Voldemort.
When does the AK blast a human body into the air? Usually, it seems.
One of the persistent arguments against the idea that Snape's Avada Kedavra on the Tower wasn't "real" is that Dumbledore’s body trajectory was inconsistent with what we saw in Frank Bryce’s death. However, a review of passages in which the Impediment, Expelliarmus, and Avada Kedavra spells are used demonstrates that these spells do not produce consistent secondary effects, even when the same person is casting the spell. While this won’t convince anyone that Snape did cast the Avada Kedavra curse on Dumbledore on the AstronomyTower, it should certainly disprove the argument that Snape couldn’t have cast the Avada Kedavra because Dumbledore’s body was blasted into the air.
The Impediment jinx impedes or stops an object from moving by temporarily freezing it. The spell sometimes lifts the target off his or her feet and sometimes does not.
  • Madame Hooch used it against Harry after he hit Draco at a Quidditch match; Harry was “knocked over backward by the force.” (OP19) 


  • Harry taught it to the DA, but they didn’t need to use cushions because they were only being frozen for a minute or two without falling over; after practicing the Impediment jinx, they pulled out the floor cushions to practice stunning (OP21)
  • In Snape’s Worst Memory, James used it against Snape “who was knocked off his feet, halfway through a dive toward his own fallen wand.” (OP28)
  • Two DE’s used it in the DoM, casting the jinx in unison against a group of three students: “Harry, Hermione, and Neville were all knocked backward off their feet. Neville was thrown over the desk and disappeared from view, Hermione was smashed into a bookcase and was promptly deluged in a cascade of heavy books; the back of Harry’s head slammed into a stone wall behind him . . .”(OP35)
  • Harry used it against Lucius Malfoy who was “blasted off his back” (from his position on the floor) and sent crashing into a dais (OP35)
  • Harry used it against Amycus and caused him to be lifted off his feet and slam into a wall and then over the wall (HBP28)
  • Harry fired one over his shoulder against Amycus and Alecto who were running toward him on the Hogwarts grounds, “ . . . and miraculously his jinx hit one of them, who stumbled and fell, tripping up the other . . . .(HBP28)

A disarming spell that sometimes lifts the target off his or her feet and sometimes does not.
  • “Snape cried: ‘Expelliarmus!’ There was a dazzling flash of scarlet light and Lockhart was blasted off his feet: He flew backward off the stage, smashed into the wall, and slid down it to sprawl on the floor.” (CS11)
  • “[Harry] pulled out his wand and shouted, “Expelliarmus!” and just as Snape had disarmed Lockhart, so Malfoy found the diary shooting out of his hand into the air.” (CS13)
  • “Harry reached his wand just in time. Lockhart had barely raised his, when Harry bellowed, ‘Expelliarmus!’ Lockhart was blasted backward, falling over his trunk; his wand flew high into the air; Ron caught it . . . : (CS16)
  • “’Expelliarmus!’ he croaked, pointing Ron’s wand at them. Harry’s and Hermione’s wands shot out of their hands, high in the air, and Black caught them. (PA17)
  • “’Expelliarmus!’ Lupin shouted. Harry’s wand flew once more out of his hand; so did the two Hermione was holding. Lupin caught them all deftly . . . (PA17)
  • “’Expelliarmus [Harry] yelled—except that his wasn’t the only voice that shouted. There was a blast that made the door rattle on its hinges; Snape was lifted off his feet and slammed into the wall, then slid down it to the floor, a trickle of blood oozing from under his hair. He had been knocked out. Harry looked around. Ron and Hermione had tried to disarm Snape at exactly the same moment. Snape’s wand soared in a high arc and landed on the bed next to Crookshanks” (PA19)
  • [During the first DA meeting] ”The room was suddenly full of shouts of ‘Expelliarmus!’: Wands flew in all directions, missed spells hit books on shelves and sent them flying into the air . . . Glancing around, he thought he had been right to suggest that they practice the basics first; there was a lot of shoddy spellwork going on; many people were not succeeding in disarming their opponents at all, but merely causing them to jump backward a few paces or wince as the feeble spell whooshed over them.  (OP 18)
  • “Snape reacted so fast it was as though he had been expecting an attack: Dropping his bag, he plunged his hand inside his robes, and his wand was halfway into the air when James shouted, ‘Expelliarmus!’ Snape’s wand flew twelve feet into the air and fell with a little thud in the grass behind him. (OP28)
  • “[Neville] pointed his wand wildly at the struggling pair [who were on the floor] and cried, ‘Expelliarmus!’ Both Harry’s and the Death Eater’s wands flew out of their hands and soared back toward the entrance to the Hall of Prophesy; both scrambled to their feet and charged after them . . . . “ (OP35)
  • “The door burst open and somebody erupted through it and shouted, ‘Expelliarmus!’ . . . Then by the light of the Mark, he saw Dumbledore’s wand flying in an arc over the edge of the ramparts . . . Standing against the ramparts, very white in the face, Dumbledore still showed no sign of panic or distress . . . : (HBP27)

Avada Kedavra Curse
Also known as “the killing curse,” the Avada Kedavra is an Unforgivable Curse that instantly kills the person or animal it makes contact with; when it hits a non-animate object, it has variable effects. An AK Voldemort cast in Godric’s Hollow is recalled as a green light in Harry’s sketchy flashback memories. Readers have seen the Avada Kedavra Curse cast numerous times in the HP series, both verbally and non-verbally (w assume it’s an AK when the light is green and the caster's intent to commit murder):
  • Babymort cast the curse on Frank Bryce in GF (verbal)
  • Fake Moody cast the curse on a spider in GF (verbal)
  • Wormtail cast the curse on Cedric Diggory in GF (verbal)
  • Voldemort cast the curse five times in the MoM battle (once verbally at Harry and four times nonverbally at Dumbledore)
  • Bellatrix cast the curse on a fox in HBP (nonverbal)
  • Snape cast the curse on Dumbledore in HBP (verbal)
The Avada Kedavra always produces a flash or jet of intense green light out of the wand and is sometimes described as accompanied by a roaring, rushing noise (Frank Bryce in GF, spider in GF) but mostly not (Cedric in GF, all Voldemort’s AK’s in the DoM in OP, fox in HBP, and Dumbledore in HBP). Also, in the battle in Hogwarts at the end of HBP, a few jets of green light are mentioned, but no sound is described.
The secondary effects of the Avada Kedavra are hotly debated since readers who argued that Dumbledore was alive frequently pointed to the description of Dumbledore’s body being blasted into the air as proof that Snape must have uttered a different non-verbal spell that superseded the spoken AK. But a closer look at the descriptions of AK usage in the series actually gives support to secondary effects of the AK that are consistent with what happened to Dumbledore on the Astronomy Tower.  In other words, Frank Bryce is the exception to what an AK will do to a human, not the rule.
Frank Bryce (AK cast by Babymort):
“And then the chair was facing Frank, and he saw what was sitting in it. His walking stick fell to the floor with a clatter. He opened his mouth and let out a scream. He was screaming so loudly that he never heard the words the thing in the chair spoke as it raised a wand. There was a flash of green light, a rushing sound, and Frank Bryce crumpled. He was dead before he hit the floor.“ (GF1)
The AK makes contact as a jet of green light and kills instantly. In GF1, we saw Frank Bryce get hit with an AK. He had been standing up, and when the curse reached him, he was killed instantly and crumpled to the floor. His body wasn’t blasted into the air, but Babymort did not have his full strength as he told Wormtail, and he had been further weakened by the journey to Little Hangleton that day. Voldemort told his Death Eaters in the graveyard after his rebirthing that after failing to retrieve the Philosopher’s Stone, he decided to put immortality aside temporarily and settle for his old body and old strength. And we know he was weaker in his rudimentary Babymort body than in his full body because the magical, psychic connection between Harry and Voldemort strengthened considerably after Voldemort’s rebirthing.  Ergo, we have to take Babymort’s weakness into account to understand why Bryce's body wasn't blasted into the air.
The spider (AK cast by Fake Moody):
“ . . . [The spider] started to scuttle frantically across the wooden surface.
Moody raised his wand, and Harry felt a sudden thrill of foreboding.
‘Avada Kedavra!’ Moody roared.
There was a flash of blinding green light and a rushing sound, as though a vast, invisible something was soaring through the air—instantaneously the spider rolled over onto its back, unmarked, but unmistakably dead. Several of the students stifled cries; Ron had thrown himself backward and almost toppled off his seat as the spider skidded toward him.” GF14
What is interesting about the spider is that it was still moving after the AK killed it. The spider died instantly, but its corpse didn’t stop moving. The verb "scuttle" indicates the spider was moving on its own initiative across the desk before being hit with the AK, but the verb "skid" clearly implies the spider was not moving on its own initiative after being hit with the AK; rather, it was moving because of the secondary effect of the killing curse.  (Note: it was pointed out in the comments that the spider could have been skidding merely because it was already moving; however, the spider flipped over first, which seems to be a secondary effect of the curse.)
Cedric Diggory (AK cast by Wormtail):
“Harry lowered his wand slightly and glanced sideways at Cedric. Cedric shot him a quizzical look. They both turned back to watch the approaching figure.
It stopped beside a towering marble headstone, only six feet from them. For a second, Harry and Cedric and short figure simply looked at each other.
And then, without warning, Harry’s scar exploded with pain. It was agony such as he had never felt in all his life: his wand slipped from his fingers as he put his hands over his face; his knees buckled; he was on the ground and he could see nothing at all; his head was about to split open.
From far away, above his head, he heard a high, cold voice say, ‘Kill the spare.’
A swishing noise and a second voice, which screeched the words into the night: ‘Avada Kevadra!”
A blast of green light blazed through Harry’s eyelids, and he heard something heavy fall to the ground beside him; the pain in his scar reached such a pitch that he retched, and then it diminished; terrified of what he was about to see, he opened his stinging eyes.
Cedric was lying spread-eagled on the ground beside him. He was dead.
For a second that contained an eternity, Harry stared into Cedric’s face, and his open gray eyes, blank and expressionless as the windows of a deserted house, and his half-open mouth, which looked slightly surprised.” (GF32)
Harry’s hands were over his face when Cedric was AK’d in GF32, but Cedric had been standing next to Harry when he got hit. Harry heard "Avada Kedavra!" and then “heard something heavy fall to the ground beside him”; when Harry opened his eyes to look, he saw Cedric’s corpse, supine in a spread-eagled position. To be spread-eagled is to be in a position in which the arms and legs are fully extended away from the body. In other words, Cedric hadn’t crumpled like Frank Bryce. If a standing man dies instantly, causing his body to crumple, his legs will buckle (as Harry’s did a moment before Cedric was killed), and he’ll end up in a semi-sprawl, but he won’t end up flat on his back with his arms and legs fully extended. Considering the position of Cedric’s body and the fact that Harry heard something heavy fall to the ground beside him after the AK was cast, it's likely that Cedric had been thrown into the air with his limbs flailing (like a rag doll, as Dumbledore had been described). Unlike Babymort, Wormtail had his full powers when casting the AK, so Cedric's body was blasted into the air.
Voldemort cast five AK’s between pages 813-815 of OP36:
  • #1 was a verbal AK cast at Harry:
 “’I have nothing more to say to you, Potter,” he said quietly. “You have irked me too often, for too long. AVADA KEDAVRA!’
Harry had not even opened his mouth to resist. His mind was blank, his wand pointing uselessly at the floor.
But the headless golden statue of the wizard in the fountain had sprung alive, leaping from it’s plinth, and landed on the floor with a crash between Harry and Voldemort. The spell merely glanced off its chest as the statue flung out its arms, protecting Harry.
‘What—?’ said Voldemort, staring around. And then he breathed, ‘Dumbledore!’” OP36
  • #2 was a nonverbal AK cast at Dumbledore
 “Voldemort raised his wand and sent another jet of green light at Dumbledore, who turned and was gone in a whirling of his cloak.” (OP36)
  • #3 was a nonverbal AK cast at Dumbledore
 “He sent another killing curse at Dumbledore but missed, instead hitting the security desk, which burst into flame.” (OP36)
  • #4 was a nonverbal AK cast at Dumbledore
 “Another jet of green light flew from behind the silver shield. This time it was the one-armed centaur, galloping in front of Dumbledore, that took the blast and shattered into a hundred pieces . . . .” (OP36)
  • #5 was a nonverbal AK cast at Dumbledore
 “ . . . one more jet of green light had flown at Dumbledore from Voldemort’s wand and the snake had struck.
Fawkes swooped down in front of Dumbledore, opened its beak wide, and swallowed the jet of green light whole. He burst into flame and fell to the floor, small, wrinkled, and flightless” (OP36)
When an AK hits an inanimate object, the object suffers physical damage, apparently depending on the type of material it's made of.  When Voldemort cast an AK at Harry in the graveyard at the end of GF, Harry ran behind a tombstone, which cracked when the AK hit it. 
The fox (AK cast by Bellatrix):
“The harsh cry startled the fox, now crouching almost flat in the undergrowth. It leapt from its hiding place and up the bank. There was a flash of green light, a yelp, and the fox fell back to the ground, dead." (HBP2)
The fox is interesting because the passage is vague.  The fox "fell back to the ground, dead," yet it isn't clear if the fox was in the air when the AK made contact (since the fox was described as leaping up the bank) or if the AK blasted the fox into the air, and its dead body fell back to the ground.  There's no way to resolve this from the passage, but suffice to say, it doesn't contradict the idea that the AK blasted the fox into the air.
Dumbledore (AK cast by Snape):
“Snape gazed for a moment at Dumbledore, and there was revulsion and hatred etched in the harsh lines of his face.
‘Severus . . . please . . .”
Snape raised his wand and pointed it directly at Dumbledore.
‘Avada Kedavra!’
A jet of green light shot from the end of Snape’s wand and hit Dumbledore squarely in the chest. Harry’s scream of horror never left him; silent and unmoving, he was forced to watch as Dumbledore was blasted into the air. For a split second, he seemed to hang suspended beneath the shining skull, and then he fell slowly backward, like a great rag doll, over the battlements and out of sight.” (HBP27)
[Thirty minutes passed by Harry’s estimate.]
“He and Hagrid moved, dreamlike, through the murmuring crowd to the very front, where the dumbstruck students and teachers had left a gap.
Harry heard Hagrid’s moan of pain and shock, but he did not stop; he walked slowly forward until he reached the place where Dumbledore lay and crouched down beside him. He had known there was no hope from the moment that the full Body-Bind Curse Dumbledore had placed on him lifted, known that it could have happened only because its caster was dead, but there was still no preparation for seeing him here, spread-eagled, broken: the greatest wizard Harry had ever, or would ever, meet.
Dumbledore’s eye were closed; but for the strange angle of his arms and legs, he might have been sleeping. Harry reached out, straightened the half-moon spectacles upon the crooked nose, and wiped a trickle of blood from the mouth with his own sleeve.” (HBP28)
Dumbledore’s body was thrown into the air and over the ramparts at the top of the Astronomy Tower. Dumbledore’s AK’d body at the bottom of the tower was described as being supine in a spread-eagled position, just as Cedric’s had been. Since both Dumbledore and Cedric had been hit with AK’s and both ended up on their backs in a spread-eagled position, this is confirmation from Rowling that what we saw happen on the tower is a bona fide reaction to the Avada Kedavra curse and that Cedric's body was thrown into the air.  Snape had his full powers when casting the AK, so Dumbledore's body was blasted into the air.
What about Dumbledore’s closed eyes?
Dumbledore’s eyes were closed when Harry viewed his body at the bottom of the Tower whereas the eyes on the corpses of Cedric and the Riddles were open. But this has nothing to do with the AK itself, but rather indicates whether the victim’s eyes were open or shut when the curse made contact.
The Riddles looked as if they had been frightened to death. Frank Bryce was looking at Voldemort and screaming when he died, so it’s a good bet his face looked the same as the Riddles. Cedric and Harry were puzzled that the TriWizard Cup had turned out to be a portkey that took them to a graveyard; they were both watching Wormtail and his bundle walk toward them when Harry was overcome with pain from Voldemort. Cedric would likely have glanced at the stricken Harry before returning his gaze to the approaching Wormtail, which is consistent with Harry’s description of Cedric’s dead face as appearing slightly surprised.  
In contrast, Dumbledore was not caught off guard, nor was he afraid, nor was he unsure of what was happening because he wanted Snape to cast the curse and, in fact, was pleading with Snape to cast it. I firmly believe Dumbledore closed his eyes before Snape cast the curse because he knew it would be harder for Snape to do it if Dumbledore was looking at him. That’s why Dumbledore’s eyes were closed when Harry saw his body.  Also, the fact that Harry described Dumbledore as appearing to be sleeping is Rowling's way of assuring the reader that Dumbledore was at peace when he died.
What about the split second Dumbledore was hanging in the air before falling?
Why did Dumbledore seem to hang in the air for a split second before slowly falling backwards out of Harry’s sight?  We learned about non-verbal spells in HBP, so I wouldn’t discount this explanation: after marshaling the volition to cast the AK that ended Dumbledore’s life instantly, Snape non-verbally held his body up briefly. This could even have been done subconsciously, harking back to PS/SS when Hagrid asked Harry if he’d ever “made things happen” when he was angry or upset. Snape was both at that moment: angry at Draco for bringing them all to that point, and upset by the passing of his friend and mentor. 
I highly recommend the following insightful essay by Helen Ketcham, who argues:
“ . . .[if] Snape’s conduct can be shown to be consistently congruent with Dumbledore’s values, principles and goals, perhaps we may infer that even such a shocking death, though a tragedy, may still not be a betrayal. My hope is to add just enough conjecture, not too wildly unsupported by the text, to the scraps and glimpses we have of Snape’s life to suggest some reasons why Professor Dumbledore persisted, and rightly so, in valuing and trusting him.”
'Good Snape' is not a 'Square Circle' By H.M. Ketcham
Was Harry released from the body-bind jinx when the AK hit Dumbledore?
Yes.  The passage was narrated from Harry's point of view, and Dumbledore’s death was surreal for Harry. It could be that Snape held up the body for a split second (I will even say it’s likely he did), but the rest of the description of Dumbledore’s fall is not related to spells cast or not cast since the descriptions of Dumbledore’s and Sirius’s “death falls” are so similar:
In OP35: “Harry released Neville, though he was unaware of doing so." . . . “It seemed to take Sirius an age to fall. His body curved in a graceful arc as he sank backward through the ragged veil hanging from the arch.”
In HBP27: "For a split second, he seemed to hang suspended beneath the shining skull, and then he fell slowly backward, like a great rag doll, over the battlements and out of sight."
One argument is that Harry remained frozen for a few seconds after the AK hit Dumbledore and that Harry was only released from the Full Body-Bind when Dumbledore’s live body hit the ground and killed him. However, as Harry, who had been pinned to the wall by Dumbledore’s nonverbal spell, watched Dumbledore’s body fall over the ramparts, he “felt as though he too were hurtling through space,” so Harry experienced a sense of movement before Dumbledore’s body hit the ground.  Harry then realized what had been "holding him against the wall was not magic, but horror and shock."  
A short time later, Harry and Hagrid were described as moving “dreamlike” toward Dumbledore’s body:
“He and Hagrid moved, dreamlike, through the murmuring crowd to the very front, where the dumbstruck students and teachers had left a gap.
So the slow-motion description of Dumbledore’s falling body, Harry’s sympathetic falling sensation, followed by his realization that shock and horror (not the spell) were holding him against the wall, and the “dreamlike” description of Harry as he walked toward the body are telling us about Harry’s state-of-mind, not that Dumbledore hadn't been killed by the AK.
Could Dumbledore have been holding up a shield so that the AK was blocked and he really died from the fall?
The trouble with this imaginative theory advanced by Red Hen is that Rowling wouldn’t cheat by using a device or spell we’d not properly been introduced to first. She’s playing by the rules, so she can’t fire a gun without showing us the gun in advance. That’s one big problem with the “magical shield that can block an AK” theory. Yes, we’ve seen an AK cast at Harry hit and crack a gravestone he ducked behind, but that’s not showing us a gun. That’s saying, well, no I didn’t show you a gun, and in fact, I’ve told you there is no such gun, but I showed you a thin metal tube, and my brilliant character made it into a gun without my telling you. That would be a cheat, and Rowling wouldn’t do it. 
All the evidence suggests that the AK was real and Dumbledore took it directly; the shield theory proposes a highly problematic solution to what boils down to the curious split-second that Dumbledore appeared to be hanging in mid-air.  A troublesome consideration is that a solution to a Rowling plot mystery should answer the question “What happened?” without turning the solution itself into a mystery in its own right.  How would Dumbledore know about this fabulous protective device when no one else in the Potterverse knows about it?  Would Dumbledore not have at least shared it with his OotP colleagues and MoM Aurors, etc.?  Is it remotely likely that Death Eaters would not know about this amazing trick?  It just isn't credible that in the time the AK has existed and been observed to hit inanimate objects without passing through to living people behind those objects that Dumbledore is the only person to have thought to construct a wearable protective shield that blocks an AK. 

Moreover, the argument that Dumbledore was holding his hand to his chest on the Tower to keep this device in place is very weak.  Why did he suddenly need to hold on to it when he hadn't in the previous three hours when he was Apparating, swimming, moving through the cave, etc.  After drinking the green potion, Dumbledore was so weakened Harry had to half-carry him, so wouldn't Harry have felt the shield?  ("And pulling Dumbledore’s uninjured arm around his shoulders, Harry guided his headmaster back around the lake, bearing most of his weight” . . . .“back under the starry sky, Harry heaved Dumbledore onto the top of the nearest boulder and then to his feet. Sodden and shivering, Dumbledore’s weight still upon him”  (HBP27))  And if Dumbledore wasn't wearing the shield in Hogsmeade but was wearing it on the Tower, when did he get it? 
It's more plausible that Dumbledore had his hand on his chest because he was 150 years old, had just drunk 12 goblets of poison, and was dying.

For more background to this shield theory and a truly wonderful historical connection between Horace Slughorn and American magician Horace Goldin, please read Gumshoe's, "Dumbledore is not Dead" essay at TLC:

What about a non-verbal spell that trumped Snape's verbal AK?
Like the magical, invisible shield, that would be a cheat because there aren't any set-ups for it.  There is no evidence that it's possible to cast a non-verbal and a verbal spell at the same time, let alone cast them simultaneously and have the non-verbal trump the verbal (as Jeremy Able at Eating Words noted, that's asking a lot--even for the brain of Severus Snape). Try shouting "Avada Kedavra!" while thinking "Wingardium Leviosa!" at exactly the same moment.  Remember that your verbal killing curse has to produce all the visual effects associated with the AK (a green light or jet) and hit but not harm the target, while at the same time, your non-verbal levitation charm has to produce the desired magic by holding up Dumbledore's body, but only for a split-second. 
Moreover, when a spell is supposed to produce a distinctive optical effect and it does, then the evidence is there that the spell was cast correctly and hence is efficacious. For instance, when Harry was trying to produce a patronus, his first few attempts were silvery, formless wisps that quickly dissolved. When he finally managed to produce one, it was a stag that cantered around the room. So Snape's AK on the Tower was effective since Snape's wand was pointed directly at Dumbledore and Snape produced a jet of green light that hit Dumbledore squarely in the chest.  It sure looked like a very powerful AK considering the reaction of Dumbledore’s body. We know of only one other spell that produces green light, and it made Ron Weasley burp slugs. The spell that hit Dumbledore blasted him into the air.
What about the trickle of blood that Harry wiped from Dumbledore’s mouth?
CSI fans like me know corpses don’t bleed because circulation has stopped, but the wife of a pathologist on a BNU HBP forum asked her husband if Dumbledore’s just-dead corpse could have bled if his teeth clamped down on his tongue or lip when his body hit the ground. The answer was yes.

Looking over the evidence, there’s only one conclusion possible IMO—Dumbledore died the instant Snape’s AK made contact.

For another demonstration of the realness of the AK with excellent arguments, please read "A Dozen Reasons Why Albus is Deader than a Dumbledorenail at TLC:

Dumbledore's Boggart

What is Dumbledore’s Boggart?
In a July 2006 Leaky Cauldron/Mugglenet interview, Rowling suggested we’d be able to develop theories about Dumbledore’s boggart from reading Harry Potter and the Half-Blood Prince
A boggart takes the form of what a person fears most, and I believe HBP reveals that Dumbledore’s greatest fear is harm coming to children under his care. Support for this theory is demonstrated in HBP chapters 25-27, the events of the night Dumbledore and Harry went to the sea cave.
The Conversation in Dumbledore’s Office
Prior to leaving for the trip to the cave, Harry had confronted Dumbledore with the news that Draco was celebrating in the RoR and that Harry had learned Snape was the eavesdropper who had carried the first part of the prophesy to Voldemort:
“You’re leaving the school tonight, and I’ll bet you haven’t even considered that Snape and Malfoy might decide to—“
“To what?” asked Dumbledore, his eyebrows raised. “What is it you suspect them of doing, precisely?”
“I . . .they’re up to something!” said Harry, and his hands curled into fists as he said it. “Professor Trelawney was just in the Room of Requirement, trying to hide her sherry bottles, and she heard Malfoy whooping, celebrating! He’s trying to mend something dangerous in there and if you asked me, he’s fixed it at last and you’re about to just walk out of school without—“
“Enough,” said Dumbledore. He said it quite calmly, and yet Harry fell silent at once; he knew he had finally crossed some invisible line. “Do you think that I have once left the school unprotected during my absences this year? I have not. Tonight, when I leave, there will again be additional protection in place. Please do not suggest that I do not take the safety of my students seriously, Harry.” (HBP25)
What’s most revealing about this passage isn’t that Dumbledore declared his concern for the students, but that Harry “knew he had finally crossed some invisible line.” Considering that Harry’s insolence toward Dumbledore in the preceding books had elicited hisses and exclamations of disapproval from the portraits on the walls of Dumbledore’s office and considering particularly Harry’s rampage in Dumbledore’s office at the end of OP when he blindly smashed Dumbledore’s delicate silver instruments while shouting at the Headmaster, it's saying something that he realized he had finally crossed a line. Dumbledore had much experience overlooking Harry’s offensive behavior to himself, but he wouldn’t overlook an accusation that he was leaving the students unprotected.
Moreover, before Harry was sent off to Gryffindor Tower, Dumbledore laid down firm rules for Harry’s protection that he repeated several times so there would be no misunderstanding and so Harry would comprehend that consenting to Dumbledore’s rules was a non-negotiable condition of accompanying him to the cave:
“I take you on one condition: that you obey any command I might give you at once, and without question.”
“Of course.”
“Be sure to understand me, Harry. I mean that you must follow even such orders as ‘run,’ ‘hide,’ ‘or ‘go back.’ Do I have your word?” 
“I—yes, of course.”
“If I tell you to hide, you will do so?”
“If I tell you to flee, you will obey?”
“If I tell you to leave me and save yourself, you will do as I tell you?”
“Yes, Sir.” (HBP25)
So before leaving for the cave, Rowling made sure we understood Dumbledore’s profound concern for the welfare of the students in his care. As a final protection for Harry, Dumbledore insisted that he put on his Invisibility Cloak for the trip to Hogsmeade.
The Experience in the Sea Cave
When they reached the cave, Dumbledore dried Harry off, insisted on using his own blood to open the cave wall, and led the way through the cave, catching Harry when he slipped, instructing Harry to stay close to the wall, to avoid the water, and to conjure fire should the Inferi leave the lake. 
When Dumbledore determined that the green potion had to be drunk in order to retrieve the Horcrux at the bottom of the basin, he again reminded Harry of the rules:
“You remember,” said Dumbledore, “the condition on which I brought you with me?”
Harry hesitated, looking into the blue eyes again that had turned green in the reflected light of the basin.
“But what if—?”
“You swore, did you not, to follow any command I gave you?”
"Yes, but—“
“I warned you, did I not, that here might be danger?”
“Yes,” said Harry, “but—“
“Well, then,” said Dumbledore, shaking back his sleeves once more and raising the empty goblet, “you have my orders.”
“Why can’t I drink the potion instead?” asked Harry desperately.
“Because I am much older, much cleverer, and much less valuable,” said Dumbledore. (HBP26)
What did Dumbledore experience when he drank the green potion in the cave? Taking their cues from Rowling, many theorists are referring to the potion as a liquid boggart, which suggests the potion would elicit different images and experiences for each potential drinker. This theory generally goes on to claim that Dumbledore was forced to imagine the deaths of James and Lily Potter, but I don’t believe that’s true. I think the drinker of the phosphorescent green potion was forced to experience Tom Riddle’s torture of  Amy Benson and Dennis Bishop during the orphanage’s annual summer outing many years earlier.
As Mrs. Cole told Dumbledore on the day he met Tom Riddle:
“Billy Stubb’s rabbit . . . well, Tom said he didn’t do it and I don’t see how he could have done, but even so, it didn’t hang itself from the rafters, did it?” . . . But I’m jiggered if I know how he got up there to do it.  All I know is he and Billy had argued the day before.  And then. . .on the summer outing—we take them out, you know, once a year, to the countryside or to the seaside—well, Amy Benson and Dennis Bishop were never quite the same afterwards, and all we ever got out of them was that they’d gone into a cave with Tom Riddle. He swore they’d just gone exploring, but something happened in there, I’m sure of it.” (HBP13)
When Dumbledore met 11-year-old Tom a few minutes later, Tom thought Dumbledore was a doctor trying to trick Tom into an insane asylum. Even though neither Dumbledore nor Mrs. Cole had mentioned any “incidents,” Riddle spontaneously denied harming Amy Benson and Dennis Bishop and clearly believed they were the reason he was being institutionalized. This is a clear hint from Rowling that Tom Riddle had done something sadistic to the two children in the cave that day:
“You can’t kid me! The asylum, that’s where you’re from, isn’t it? ‘Professor,’ yes of course—well, I’m not going, see? That old cat’s the one who should be in the asylum. I never did anything to little Amy Benson or Dennis Bishop, and you can ask them, they’ll tell you!” (HBP13)
What might he have done? We can somewhat guess from the magical abilities Tom boastingly told Dumbledore he had developed on his own:
“I can make things move without touching them, I can make animals do what I want them to do, without training them. I can make bad things happen to people who annoy me. I can make them hurt if I want to.” (HBP13)
The first clue that Dumbledore was reliving the torture of Amy and Dennis through the potion is that Dumbledore was speaking in quite childlike language for most of the time he was drinking it:
After 3 ½ goblets of green potion Dumbledore’s eyes closed, his face twitched, he appeared to be dreaming a horrible dream, and he spoke in a frightened voice:
“I don’t want . . . don’t make me . . . don’t like . . . want to stop ‘ ‘ ‘
After four full goblets:
“No . . .I don’t want to . . . I don’t want to . . . Let me go . . . Make it stop, make it stop.”
After five goblets, Dumbledore screamed:
No, no, no, no, I can’t, I can’t, don’t make me, I don’t want to . . .”
After six goblets:
“It’s all my fault, all my fault,” he sobbed. “Please make it stop, I know I did wrong, oh please make it stop, and I’ll never, never again . . . “
After seven goblets, “Dumbledore began to cower as though invisible torturers surrounded him; his flailing hand almost knocked the refilled goblet from Harry’s trembling hands as he moaned,"
“Don’t hurt them, don’t hurt them, please, please, it’s my fault, hurt me instead . . . “
After eight goblets Dumbledore shook from head to toe and fell forward screaming and hammering his fists on the ground:
“Please, please, please, no . . . not that, not that, I’ll do anything . . .“
On the ninth goblet, Dumbledore “drank like a child dying of thirst, but when he had finished, he yelled again as though his insides were on fire”:
“No more, please no more . . .”
After the tenth goblet, Dumbledore began to scream in more anguish than ever:
"I want to die! I want to die! Make it stop, make it stop, I want to die!”
After the eleventh goblet:
After the twelfth goblet, Dumbledore collapsed unconscious.
Although it’s a popular theory that the potion made Dumbledore think of the death of the Potters, does that appear to be the case when looking closely at what Dumbledore was saying? If he had been thinking of the Potters, why would he say, “Let me go”?  I contend that Dumbledore was reliving the torture of the children while drinking the potion and was speaking as the children had spoken to Tom Riddle, who was probably  punishing them for something.  In one place, Dumbledore was even described as drinking “like a child dying of thirst,” and that is a curious thing for Rowling to have written. Would we have been less sympathetic if Dumbledore had been described as “drinking like a man dying of thirst?” No, so the reference to a child is a deliberate clue that Dumbledore was reliving the torture of Amy Benson and Dennis Bishop in that cave.
Dumbledore was speaking as the children were speaking in the memory, but with one exception that occurred about halfway through the potion. Notice the shifting pronouns in the following two sentences that were spoken in succession:
“It’s all my fault, all my fault,” he sobbed. “Please make it stop, I know I did wrong, oh please make it stop, and I’ll never, never again . . . “
[“Dumbledore began to cower as though invisible torturers surrounded him; his flailing hand almost knocked the refilled goblet from Harry’s trembling hands as he moaned,]
“Don’t hurt them, don’t hurt them, please, please, it’s my fault, hurt me instead . . . “
We’re thrown off by the repetition of “my fault” in both sentences, but clearly the first voice (child) knows why the torture is happening (“It's all my fault . . . I know I did wrong . . . I’ll never, never again . . .”) whereas the second voice (Dumbledore) says, “Don’t hurt them” and “hurt me instead.” This is the only one of Dumbledore’s utterances in which the speaker 1) is not the victim, 2) refers to more than one person being hurt, 3) uses a third person pronoun, and 4) asks that the torture be redirected to himself.  In the other utterances, it’s clear that the speaker is begging that the torture he or she is experiencing be stopped.
And very importantly, “Don’t’ hurt them” was spoken at the only time during the potion drinking that Dumbledore cowered and appeared to be trying to push something away from him, which is key to understanding this passage. The physical threat immediately upon the children in his potion-induced dream spurred Dumbledore’s desire to save them to such a degree that his own voice broke through the mental incapacitation caused by the potion.  This happened two more times that evening: first, when the Inferi threatening Harry enabled him to rally to conjure a protective ring of fire, and second, when the Dark Mark threatening the students at Hogwarts enabled him to rally to race to the Astronomy Tower.  In all three examples, Dumbledore’s sense of impending physical danger to children worked as a stimulant that enabled a temporary recovery in the midst of overwhelming physical or mental incapacitation. Moreover, Dumbledore’s “hurt me instead” request to the invisible torturer in the cave is a foreshadowing of what would happen shortly on the Astronomy Tower.
This momentary break-through is consistent with Dumbledore’s willingness to sacrifice himself, demonstrated by the conditions he set upon Harry before they left Hogsmeade (“If I tell you to leave me and save yourself, you will do as I tell you?”) and to his ultimate sacrifice on the Astronomy Tower when he pleaded with Severus Snape to cast the Avada Kedavra that would end Dumbledore’s life, thereby saving Draco from becoming a killer and preserving Snape’s life to help Harry defeat Voldemort.
Why would Voldemort create a potion that would cause the drinker to relive the experience of Amy and Dennis? Because Tom Riddle was proud of torturing those children with powers he had developed on his own. And just as he had gotten away with framing Hagrid for killing Moaning Myrtle but created the diary so he could take full credit for opening the chamber, so he left behind a record in the form of a potion that revealed what he had done to the orphans in the sea cave. 
This fits a pattern whereby Voldemort's Horcruxes and their hiding places are chosen to showcase his magical brilliance in places he considers significant to his own very special life. Moreover, he always leaves enough evidence to establish what he did in those places.
1) The Riddle Diary Horcrux. 

The diary once owned by T.M. Riddle was a weapon Horcrux constructed to open the Chamber of Secrets so that Tom Marvolo Riddle could at last get the credit he had been forced to give to Hagrid in 1943.  He wanted people to know, via the diary, that Tom Marvolo Riddle was the true Heir of Slytherin who had been brilliant enough as a fifth year student to find and open Slytherin’s Chamber of Secrets and frame Hagrid for the crime (which is why the memory of the framing of Hagrid was placed in the diary).  Lucius was only temporarily holding it; its ultimate destination was Hogwarts, where the original events had taken place.
2) The Peverell Ring Horcrux.  

Riddle could easily have modified Morfin's memory to make him think the ring was safe at Gringotts so that Morfin’s mind would be easy over the fact that Marvolo’s ring was no longer on his finger. That way Morfin wouldn’t have been yammering about losing Marvolo’s heirloom ring when the murder of the Riddles was being investigated. As Dumbledore told Harry:
“[Morfin] permitted himself to be led off to Azkaban without a fight. All that disturbed him was the fact that his father’s ring had disappeared. ‘He’ll kill me for losing it,’ he told his captors over and over again. ‘He’ll kill me for losing his ring.’” (HBP17). 
The false memory Riddle did plant in Morfin’s mind was so powerful that Morfin bragged about killing the Riddles, so why leave a loose end knowing that Morfin would obsess about the missing ring and potentially give the game away by hinting that someone else was involved? Frank Bryce had seen a teenage boy at the Riddle house that day, so that fact added to Morfin’s state of agitation was a huge risk. But from Voldemort’s point of view, it made sense to leave that loose end because he was planning to wear the ring at Hogwarts long enough for everyone to see it before returning it to the Gaunt ruins, thereby leaving evidence that Tom Marvolo Riddle was the mastermind of the entire event: he had killed the adult Riddles using Morfin’s wand, framed Morfin with a powerful false memory, and stolen the Peverell ring. It fits the diary pattern in that he couldn’t resist leaving evidence of evil he was proud of committing and had managed to cover up. He hid the ring in the place where his Slytherin blood had resided, making it a significant location.
3) The Slytherin Locket Horcrux. 

This seems to break the pattern of connecting a Horcrux to a location closely associated with that particular Horcrux; however, there is a connection between the cave and locket via Parseltongue. The ability to speak to snakes was Slytherin’s signature power, and young Tom Riddle told Dumbledore that it was on the orphanage’s annual outings that he discovered his ability to speak to snakes. So in the cave, one of the locations associated with a summer outing, he decided to hide Slytherin’s locket; the cave was definitely significant to Riddle because he had used it to abuse two children magically, using powers he had developed without any training.  It fits Voldemort’s pattern that the potion would make the drinker relive the torture of Amy Benson and Dennis Bishop in order to know what Voldemort had done there, just as he had with the diary and ring.

4) I speculate in another essay that the Hufflepuff Cup has been Transfigured into the Medal for Magical Merit and hidden in the Hogwart's trophy room.  This would be Hogwarts as a significant place because Tom Riddle was happy and had learned to develop his magical powers there  (as opposed to the Diary Horcrux that was more specifically related to the Chamber of Secrets).  The object we’ve seen most likely to be the Transfigured cup is Tom Riddle’s Medal for Magical Merit. I had at first questioned it because Voldemort hates his Muggle name, but it fits with his pattern of leaving clues to what he's done. And I won’t be surprised if the medal is examined closely and found to have a tiny badger on it similar to the tiny snake on the bathroom tap marking the opening to the Chamber of Secrets.
Getting back to Hogsmeade
The potion was also a poison if Hermione’s hint at the beginning of HBP was a foreshadowing as it appears to have been: when she saw Dumbledore’s hand at the start of term feast in September, she said “"But there are some injuries you can't cure . . . old curses . . . and there are poisons without antidotes. . . ." (HBP8) Dumbledore later confirmed that a terrible curse upon the ring had damaged his hand, so we should consider her comment a hint that we were going to see a poison that had no antidote. The poisoned mead did have an antidote, so the green potion must also have been a poison that did not have an antidote. Dumbledore said Voldemort wouldn’t want the drinker to be killed right away because Voldemort would want to question the person who took the Horcrux. But would Voldemort go to all the trouble to make the cave Horcrux as difficult to reach and obtain as he did only to use a non-deadly potion or one containing a poison that could be neutralized with a bezoar or antidote? No. And from the effects the potion had on Dumbledore, we can expect that it was ending his life.
After drinking the twelfth goblet of potion, Dumbledore collapsed unconscious. Harry was able to revive him with two Rennervate! spells, after which Dumbledore’s eyes flickered and he asked for water. As Harry unsuccessfully tried to give Dumbledore water, he had to raise the weakened Dumbledore’s head to let him drink, and at one point, Dumbledore rolled onto his side and drew “great, rattling breaths that sounded agonizing.” When Harry noticed that Dumbledore’s breath was fading, he turned to the lake for water and spilled it on Dumbledore’s face as an Inferius pulled him backwards. Harry forgot that the Inferi could be driven back by fire, and his shouted spells were useless against them; they rose up from the lake, lifted him off his feet and began carrying him to the water. Suddenly fire erupted because Dumbledore, stimulated by Harry’s helplessness, had rallied from his incapacitated state to save him:
“But then, through the darkness, fire erupted: crimson and gold, a ring of fire that surrounded the rock so that the Inferi holding Harry so tightly stumbled and faltered . . . Dumbledore was on his feet again, pale as any of the surrounding Inferi, but taller than any too, the fire dancing in his eyes; his wand was raised like a torch and from its tip emanated the flames, like a vast lasso, encircling them all with warmth.” (HBP27)
Dumbledore scooped up the locket, gestured Harry to his side, led Harry safely to the boat, and then when the Inferi had slipped back into the lake and the immediate danger was over, Dumbledore once more failed physically as “all his efforts seemed to be going into maintaining the ring of protective flame round them."  Dumbledore required Harry's help getting into the boat. Only when they reached the safety of the shore did Dumbledore let his wand hand fall, and the ring of fire vanished. Dumbledore then needed to lean against the cave wall:
“I am weak . . .” he said.
“Don’t worry, sir, said Harry at once, anxious about Dumbledore’s extreme pallor and air of exhaustion. “Don’t worry, I’ll get us back . . .Lean on me, sir . . .”
And pulling Dumbledore’s uninjured arm around his shoulders, Harry guided his headmaster back around the lake, bearing most of his weight.” (HBP27
Harry gave the blood tribute to open the archway, then “back under the starry sky, Harry heaved Dumbledore onto the top of the nearest boulder and then to his feet. Sodden and shivering, Dumbledore’s weight still upon him,” Harry Apparated them back to Hogsmeade, but no sooner had they arrived when “Dumbledore staggered against him. . . . . And to Harry’s horror, Dumbledore sank to the ground.” (HBP27)
Rosmerta appeared, pointed out the Dark Mark over the Astronomy Tower, and Dumbledore revived just as he had when Harry had been attacked by the Inferi:
“When did it appear?” asked Dumbledore, and his hand clenched painfully upon Harry’s shoulder as he struggled to his feet.”
“We need to return to the castle at once,” said Dumbledore. “Rosmerta”—and though he staggered a little, he seemed wholly in command of the situation—“we need transport—brooms—“
“ . . . Harry and Dumbledore kicked off from the ground and rose up into the air. As they sped toward the castle, Harry glanced sideways at Dumbledore, ready to grab him should he fall, but the sight of the Dark Mark seemed to have acted upon Dumbledore like a stimulant: He was bent low over his broom, his eyes fixed upon the Mark, his long silver hair and beard flying behind him on the night air.” (HBP27)
The conversation on the AstronomyTower
They reached the Tower safely, but,
In the dim green glow from the Mark, Harry saw Dumbledore clutching at his chest with his blackened hand.” (HBP27)
Dumbledore was weakening again and sent Harry to get Severus Snape; however, he heard Draco pounding up the stairs, and in another act of self-sacrifice, he used the few seconds he had to freeze Harry with a full body-bind spell.  Harry could not understand at first because Dumbledore had used a nonverbal spell, and Harry surmised that by casting the freezing spell on Harry, Dumbledore had used the seconds available to him immobilize Harry rather than defend himself.  But even in light of Dumbledore's weakness, is that all Dumbledore had been able to do?

In OP27, when the DA had been busted and Dumbledore was about to be arrested by two Aurors on Fudge's order, Dumbledore managed to knock out Fudge, Umbridge, Shacklebolt, and Dawlish single-handedly while sparing McGonagall, Harry, and Marietta.  Surely even weakened Dumbledore could take on two sixth year students by himself.  But Dumbledore didn't take action to defend himself against Draco.  Dumbledore wanted to talk to Draco to save him from becoming a killer, so in freezing Harry and allowing Draco to expel his wand over the ramparts, Dumbledore allowed Draco to appear to have power over Dumbledore.  Had Dumbledore tried to body-bind Draco as he had with Harry, Draco wouldn’t have come to any self-awareness, and if Dumbledore had kept his wand and allowed Draco to keep his, Draco would have been too threatened to learn anything from Dumbledore.
As their conversation progressed, Dumbledore, wandless and defenseless, continued to slide down the rampart as he became physically weaker from the poison. Dumbledore had wanted to talk to Draco all year but knew he couldn't without endangering the boy's life, so by allowing himself to be weak (magically and physically) before Draco, he bought time to speak personally to him— to make Draco see that he wasn't a killer by reminding him several times of the task he was there to perform, to affirm his personal trust in Severus Snape, to acknowledge that Draco's his “crude and badly judged measures” with the necklace and mead had not resulted in permanent harm to Katie and Ron, and most importantly, to make Draco realize that help would be available to him and his family through the Order.
In the context of Dumbledore’s boggart, the whole conversation was about saving Draco. The two times Dumbledore reproved Draco occurred when he referred to Hermione as a Mudblood (“Please do not use that offensive word in front of me”) and when Dumbledore thought Draco had allowed the werewolf Fenrir Greyback into the school (“ . . .I am a little shocked that Draco here invited you, of all people, into the school where his friends live . . .”). (HBP27)
Dumbledore made the ultimate sacrifice for his current and future students by pleading with Snape to kill him on the Tower, thereby preventing Draco from killing while saving Snape’s life because of the Unbreakable Vow. By preserving Snape, who is now in a stronger position with Voldemort, Snape will be able to help Harry vanquish Voldemort, which was always Dumbledore's goal. And evidence that Draco was "saved" is that when Dumbledore said he was shocked that Draco invited Fenrir into the school,  Draco was more concerned to assure Dumbledore's that he had not done so than he was concerned about the opinions of the Death Eaters listening behind him; in other words, even though he knew Dumbledore was going to die that night and he would be returning to Voldemort in the company of the DE's, he nevertheless openly sought Dumbledore's approval despite the insult to the DE's behind him.
In the space of HBP chapters 25 through 27, it’s very clear that Rowling has arranged two scenes in which Dumbledore’s concern for the safety of children entrusted to him form a pair of bookends on either side of the cave visit. The bookend passages and Voldemort’s Horcrux patterns are the key to understanding what happened to Dumbledore when he drank the green potion.  And given Rowling’s suggestion that theories about Dumbledore’s boggart could be developed from HBP, I believe these scenes collectively demonstrate that his boggart would take the form of harm befalling children in general, and students under his care in specific. 

Fantastic Potions and How They Helped Albus Dumbledore in HBP

Reconciling the death of Albus Dumbledore with Severus Snape's loyalty to him.
On Aug 12, I revised and vastly expanded the essay and changed the title to “Fantastic Potions and How They Helped Albus Dumbledore during HBP”; it was reworked to include excellent comments from readers, to fill in areas that were unclear, to include my latest ideas regarding events on the night of the cave visit (the Felix Culpa Theory), and to integrate other evidence for Good!Snape I was going to use in a separate essay.
On Aug 29, I expanded the background to the Stoppered Death theory to explain how the theory was introduced on the summer 2005 BNU HBP class.  To make room, I moved the AK section to a separate post.
The Avada Kedavra was Real and Instantly Ended Dumbledore's Time on Earth
Need convincing?  Follow the link:
The Stoppered Death Theory
Theories involving Snape's claimed ability to make a potion able to "even stopper death" were in play before the release of HBP as readers, prompted by a challenge from JK Rowling, tried to figure out how Voldemort was able to survive the backfired killing curse at Godric’s Hollow. One theorist posited Snape as the expert who had brewed a potion for Voldemort that prevented him from dying ( With the publication of HBP, readers learned that Horcruxes were actually the answer to Voldemort’s survival; that clever theoriest was on the “Stoppered Death” trail but had the wrong recipient for Snape’s fantastic potion. 
Textual clues strongly point to Albus Dumbledore during HBP as the recipient of the potion able to stopper death, so I have confidence in The Leaky Cauldron's Cathy Liesner's Stoppered Death Theory that the curse on the Peverell ring was lethal, but Snape was able to “stopper,” or temporarily postpone, Dumbledore’s death. Cathy was co-moderator with John Granger (Looking for God in Harry Potter) of the Barnes & Noble University HBP online class in summer 2005. Cathy and others had noticed a number of references in HBP pointing to Snape's first potions class in PS/SS.
In the wee hours of August 7, Cathy posted the following at BNU with the subject title “Stoppered Death”:
"I was responding to someone at the Leaky Forum who was sure that Dumbledore was not dead, that somehow the Dumbledore we saw on the tower was only partly there and some portion of him had been preserved in order to return. I personally feel that would be horribly out of character for Dumbledore who had said "After all, to the well-organized mind, death is but the next great adventure." (SS17)
But what occurred to me was that on the tower, while offering protection to Draco from the Dark side, Dumbledore said, "He cannot kill you if you are already dead."
Back before the start of term, Dumbledore destroyed the ring Horcrux...and almost died: "Had it not been--forgive me the lack of seemly modesty--for my own prodigious skill, and for Professor Snape's timely action when I returned to Hogwarts, desperately injured, I might not have lived to tell the tale..."(HBP 23)
Snape's intervention? Could it possibly be related to this: "...I can teach you how to bottle fame, brew glory, even stopper death..." (SS8)
Could it be that Dumbledore had been a walking dead man since the ring Horcrux had been destroyed? He spent the entire book putting his affairs in order, getting Harry ready to take on the challenge before him. Could it be that rather than "murdering" Dumbledore, Snape released the stopper he'd placed on DD's death and allowed him to die?
True, Snape used the Avada Kedavra, but I believe it was to maintain his place inside the Death Eaters...a position that, I believe, will somehow prove crucial for Harry's triumph. Snape is not a murderer...he'd merely postponed DD's death.
What do you think? Is there anything to this theory?”
Two hours later, responding to a comment to her theory, she wrote:
“When I originally read Snape's quote, I assumed he was referring to poison, and thought it disturbing he would offer to share his abilities in poisonmaking to his class! It was the movie's misquote about "putting a stopper to death" that changed my impression to stopping the flow of life from the body, keeping death away by keeping life locked in. DD's hand was withered and black made me think of the use of a tourniquet...keeping death from flowing from the point of entry the way you would prevent venom from flowing to the heart. (Of course, the curse could have been venom-related, for that matter.)
And as is suggested by your "nick" comment, perhaps the potion in the basin wasn't even that deadly, but weakened as he was, it caused the "stopper" to be removed and reinitiated his dying.”
Many BNU readers quickly responded with praise, supporting textual evidence, and explication for Cathy’s Stoppered Death theory. Good!Snape readers were exultant to have a theory that vindicated Snape’s actions on the Tower, and they posted observations that the Stoppered Death theory explained how Snape could cast the AK without murdering an innocent man, why Dumbledore would suddenly visit the Dursleys and take them to account, why Dumbledore seemed to be putting his affairs in order throughout the book, how Dumbledore and Snape seemed to have made plans for Dumbledore’s death, how Snape seems to have surprising skill and aptitude for the healing arts (as when he healed the curse on Katie Bell), why Dumbledore was giving Harry personal lessons, why Dumbledore suddenly gave Snape the DADA position, why Dumbledore trusted Snape, why Dumbledore pleaded with Snape on the Tower, how Dumbledore may have planned to give up his life to save Snape and Draco, how Dumbledore’s sacrifice benefits Harry by enabling Snape to work closely with Voldemort and strengthens Snape’s position, and how Fawkes may well be the means by which Harry is convinced of Snape’s loyalty to Dumbledore.  The archive is no longer online (I got a copy of the files from a BNU "saver"), but BNU member Janet Batchler returned from vacation to read the discussion of Cathy’s elegant theory and was so impressed she left a comment on the thread at 2AM on August 18 that became the basis of a blogpost summarizing the main points of the theory as discussed on Cathy's thread up through the time of Janet's own "Stoppered Death" thread comment:
Cathy Liesner’s BNU co-moderator, John Granger, was quick to congratulate her for cracking the code and posted an essay at 6PM on August 18 about why HBP was the best HP novel that included a section on Cathy’s theory. He gathered much of the supporting evidence on the Stoppered Death thread and expounded it in the context of the larger story; he also expanded the textual support for the theory with additional evidence he had noticed, such as Snape's question about the difference between an Inferius and a ghost (Albus, who is between the two), Snape's willingness to make the UV, Snape’s rage at being called a coward, and other textual support that I don’t have in my essay. Unfortunately, John’s HBP essay is no longer online, but he is expanding his elucidation of Cathy’s Stoppered Death theory for a book he plans to publish soon (hint!).
As noted, I'm convinced that Cathy Liesner figured out the theory that explains most of the action in HBP. I'm delighted to have heard of her theory and thrilled to share it with HP fans along with my own "Stoppered Death" developments.  I'm not sure if I'll be right, but I'm sure Cathy Liesner will be. 
What’s gives support to the Stoppered Death theory?
The idea of temporarily extending life beyond its natural end was foreshadowed in PS/SS with the Elixir of Life when Nicholas Flamel destroyed the Philosopher’s Stone, but he and Perenell used some stored Elixir of Life to set their affairs in order before dying, which is a parallel to the Stoppered Death potion Dumbledore took at the beginning of HBP and his reasons for taking it. 
HBP is about fantastic potions and Potions Masters. The book title refers to Severus Snape, Potions Master. Hogwarts had a new Potions Master. Harry used the annotated textbook of a potions genius, who turned out to be Severus Snape, who was a classmate of Lily Potter, who, in a bombshell disclosure, was described as a potions whiz. There are at least two direct references in the HBP text to “Snape's first potions class”; there are references to the Draught of Living Death and bezoars, both of which Snape discussed in that first class, in a chapter titled "The Potions Master." Rowling clearly set out anvil-sized hints for us to go back to that first class, and when we do, we find Snape's lyrical speech in which he claimed to be able to make a potion that could "even stopper death."
Moreover, there are many references to Inferi throughout HBP: they were mentioned in the MoM security leaflet Harry had on Privet Drive, Dumbledore defined Inferi to Harry on the way to see Slughorn, Snape showed a picture of a corpse attacked by an Inferius to his first DADA class, a student asked a question about Inferi, Mundungus was impersonating an Inferius during a burglary, Snape discussed the difference between a ghost and an Inferi with his DADA students, the lake in the sea cave was full of Inferi, Harry imagined seeing Inferi in Hogsmeade, the merpeople at Dumbledore's funeral reminded Harry of Inferi, etc.
It's important to the theory, I think, that Harry's information about Inferi came from Dumbledore and Snape, the two people in HBP who knew about Dumbledore's condition.  When Snape asked Harry in his DADA class to tell him the difference between a ghost and an Inferius, the answer was “Albus Dumbledore. In Snape’s question, there is a link to PoA, when Snape, covering DADA for Lupin, asked the class how to distinguish between the werewolf and the true wolf. Just as Snape had given a hint about Lupin’s condition in PoA, Snape was giving a hint about Dumbledore’s condition in HBP.  And in both examples, Snape was providing a "master potion" to each man since Lupin himself described the potion as "very difficult to brew" (OP18).  And in another link to "Potions Masters," we learned from Potions Master Horace Slughorn that the Wolfsbane Potion Snape made for Lupin was invented by a wizard named Damocles who had been a student of Slughorn (just as Snape had).
The frequent references to Snape’s first potions class in PS; the frequent references to Inferi, Dumbledore's definition to Harry and Snape's question about the difference between an Inferius and a ghost, and Dumbledore’s statement to Draco on the Tower that “He cannot kill you if you are already dead” are very deliberate clues unified through the Stoppered Death theory.
Canon supports the idea that the curse on the Peverell ring in July 1996 nearly ended Dumbledore's time among the living. When he visited the Dursleys, his wand hand was blackened and “dead-looking.” When Hermione saw the hand at the start of term feast, she said “"But there are some injuries you can't cure . . . old curses . . . and there are poisons without antidotes. . . ." (HBP8) Hermione is a source of reliable information and often foreshadows events, so that was a clue that Dumbledore's hand had been damaged by a deadly curse, and indeed, he later confirmed that a terrible curse upon the Peverell ring had damaged his hand, and if not for his own prodigious skill and Snape’s timely actions, he would not have lived to tell the tale.
How do you stopper a death?
While there is no canon to explain what a Stoppered Death potion does, the original use of the word “stopper” was a “stopper knot” that creates a bulge on the bitter end of a line to prevent it from escaping through a fitting. A similar term mentioned by an anonymous commentator is a stopper used in an old-fashioned hand spinner that stops the thread from falling off the spool and unraveling. In the context of a potion that can “stop death,” these examples call to mind the Fates, goddesses of Greek mythology, who control a person’s destiny by spinning, measuring, and cutting the Thread of Life, and call to mind Severus Snape as both the spinner of Spinner’s End and the Potions Master able to “even stopper death.” So perhaps stoppering a death is figuratively like a tying a stopper knot to the bitter end of the “Thread of Life” as it rapidly reaches the end of its length; death (the separation of body from spirit) would result if the thread escaped.
My guess for two components of the Stoppered Death potion are 1) phoenix tears for their healing properties and the phoenix's ability to regenerate itself and 2) unicorn hair because of its exceptional strength and ability to bind. These ingredients work perfectly with the idea of the stopper knot if the unicorn hair forms the figurative knot preventing the Thread of Life from escaping while the phoenix tears cause the last moment of life to be continuously regenerated. It is in this way that we see a drinking, walking, talking, thinking, vital Dumbledore in HBP even though, because his last moment was being continuously regenerated, he technically had died.
Could magic do that? We know Fawkes regenerates regularly, and we’ve seen an example in the Department of Mysteries of an action in time repeating in a continuous loop; tellingly, the hummingbird is in the Time Room, surrounded by clocks and where the Time Turners were kept. The hummingbird under the bell jar is endlessly re-hatched and re-shelled, yet it never completes its life cycle:
“Drifting along in the sparkling current inside was a tiny, jewel-bright egg. As it rose in the jar, it cracked open and a hummingbird emerged, which was carried to the very top of the jar, but as it fell on the draft, its feathers became bedraggled and damp again, and by the time it had been borne back to the bottom of the jar, it had been enclosed once more in its egg.” OP34
Phoenix tears and unicorn hair seem right as Stoppered Death ingredients because of the contrast to the snake venom and unicorn blood potion that Babymort used to keep himself alive for a year in GoF. Nagini's venom dissolved Arthur’s stitches, and the healers at St. Mungo’s had to give him blood-replenishing potions until they could find a way to heal him; drinking unicorn blood will keep someone alive who is near death, but the cost of killing a pure and defenseless animal is that the drinker will lead a cursed life. In contrast, Fawkes's tears magically heal fatal wounds, even wounds made by venomous basilisk fangs, and unicorn hair is a powerful binding ingredient freely gathered where unicorns shed it in the forest. 
The difference between these potions encapsulates the differences between Dumbledore and Voldemort in terms of what they will do, under what conditions, to magically extend life. Dumbledore will not take an action that requires killing or coercing a creature to provide potion ingredients; Voldemort does both. Dumbledore seeks a temporary extension in order to make the WW better and freer before he moves on to the "next great adventure"; Voldemort seeks control over the WW and fears death. Dumbledore’s solution is to keep his body and spirit held together through white magic; Voldemort’s is to tear his apart through dark magic in the hope of achieving immortality.
I’m guessing the Stoppered Death potion is almost unknown and unobtainable due to the need for phoenix tears to make it. After all, phoenixes are rare creatures that are virtually impossible to domesticate. Their tail feathers can be collected in the mountaintops where they dwell, but their tears would only be accessible from a phoenix that had become the companion of a wizard as Fawkes had with Dumbledore. The fact that Dumbledore’s hand couldn’t be directly healed by Fawkes's tears tells me the curse on the ring was extremely dark magic even if its effects weren’t instantaneously lethal. And perhaps phoenixes don’t cry on demand but need to produce tears in the required quantity relative to the immediate need of the person the phoenix wants to heal, so the potion couldn’t be prepared ahead. Dumbledore had to return to Hogwarts after being wounded by the curse on the Peverell ring was so Snape could concoct the potion with Fawkes’s tears. Dumbledore destroyed the ring in July, so Snape should have been back at his Spinner's End house; since he was at Hogwarts, he must have been waiting at the school at Dumbledore's request "just in case."
The beauty of the “Stoppered Death” Theory . . . is that it explains
  • why Snape was willing to make the Unbreakable Vow with Narcissa (because he knew Dumbledore would not live more than a year and he could possibly hold Draco back long enough for the stopper to come out of Dumbledore’s death, which would neutralize the UV, and perhaps in the hope that Draco would confide in him if he made the UV with Narcissa),
  • why Dumbledore made an unusual visit to the Dursleys (to reproach them for their treatment of Harry over the prior 15 years and inform them (and Harry) that Harry will need to visit one more time before his 17th birthday (because he wouldn’t be alive at the end of the year to tell them),
  • why Dumbledore was in a rush to give Harry information and to push Harry to get the Horcrux memory from Slughorn (because Dumbledore didn’t have long to live),
  • why Dumbledore gave Snape the DADA job in HBP (because Dumbledore knew he wouldn’t live to the next school year, and if they worked it carefully, they could save Draco and protect Snape from the UV by buying enough time for Dumbledore to die from the potion wearing off and let Snape take credit for killing Dumbledore),
  • the meaning of the conversation Hagrid overheard when Snape told Dumbledore that he took too much for granted and maybe he didn’t want to do it anymore (in other words, Snape was saying he would rather die from the Unbreakable Vow than unstopper Dumbledore’s death while the potion was still working),
  • why Dumbledore wanted Snape to unstopper his death if necessary (Dumbledore knew Draco was assigned to kill him during the school year of HBP and that Snape had made an Unbreakable Vow to kill Dumbledore if Draco couldn’t manage it. So Dumbledore, in order to save Draco from becoming a murderer and to keep Snape alive to help destroy Voldemort from within the inner circle, made Snape agree to fulfill the Unbreakable Vow and unstopper Dumbledore’s death if it came to that point),
  • why Dumbledore made Harry promise to keep forcing him to drink the lethal poison in the cave even though Dumbledore had already said it would kill the person who drank it (because Dumbledore was already dead, so Harry wasn’t killing him at all),
  • why Dumbledore was pleading with Severus on the Astronomy Tower (he was asking Snape to unstopper his death even though Snape had told him he didn’t want to do it in the conversation overheard by Hagrid, etc.),
  • the meaning of the "revulsion and hatred" on Snape's face when he was about to pull the stopper out (because he hated what he was doing. Snape and Harry were described in similar terms in the act of harming Dumbledore ("Harry hated himself and was repulsed by having to force the last of the poison into Dumbledore.") The difference is that we were being told what Harry was thinking without being given a description of Harry's face whereas we were given a description of Snape's face without being told what Snape was thinking.),
  • how Snape was able to AK Dumbledore on the tower without committing murder (since Dumbledore was already dead. What Snape did was unstopper Dumbledore’s actual death and allowed it to proceed. That is why Dumbledore could morally ask Snape to AK him and why Snape could morally comply), and
  • why Snape was so enraged when Harry called him a coward for killing Dumbledore even though Snape had not been enraged when Harry called him a coward for refusing to fight w only a few moments earlier (because it wasn’t cowardly of Snape to throw the AK at Dumbledore, nor was it murder: it was a wrenching act that he did to fulfill the agreement he made with Dumbledore).

Why would Dumbledore stopper his death?

Dumbledore said “to the well-organized mind, death is but the next great adventure,” so he wasn’t afraid of death. But would Dumbledore’s mind have been calm and settled if faced with imminent death from the ring curse if that meant leaving Harry without the knowledge of Voldemort’s Horcruxes that Harry needed in order to destroy Voldemort? I think not. I fully believe Dumbledore availed himself of a non-dark option like Stoppered Death to buy himself time to educate and train Harry. After all, Dumbledore knew the prophesy and knew Harry was the WW’s only hope of vanquishing Voldemort. That was Dumbledore’s goal as well, and he wanted to assist Harry, especially in sparing Harry by destroying as many as he could himself. Had the real Horcrux been in the cave, Dumbledore would have managed to destroy two that were protected with magic that couldn't be neutralized with counterspells or antidotes. 
Moreover, Dumbledore was Flamel’s partner in alchemy, an active participant in alchemical research even if he hadn’t taken the Elixir of Life himself. Nicholas was 660 years old or so, and Dumbledore was still living his natural life at 150, so we don’t know if Dumbledore would have taken some Elixir in the future. He never implied that the Flamels were taking the Elixir because they didn’t have well-organized minds or were afraid of death, and there is no inherent contradiction between choosing to extend your life to do important work and regarding death as the next great adventure. Flamel was the only known maker of the Philosopher’s Stone and therefore the most brilliant alchemist ever born, so his reason for using the Elixir must have been to continue his work. Likewise, Dumbledore was in a unique position--because of the knowledge he had amassed of Voldemort’s personal history--to educate and train Harry in the strategy necessary to defeat Voldemort. Once Dumbledore had done all he could in that Stoppered Death year (by directly training Harry and perhaps archiving more information to leave to him), he would move on.
How did the Stoppered Death potion influence events in HBP?
Knowing that Dumbledore was on borrowed time and knowing that Draco had to kill Dumbledore by the end of the school year or be killed himself, Dumbledore and Snape tried to run out the clock during HBP by thwarting Draco’s attempt to kill Dumbledore (Snape was putting Crabbe and Goyle in detention to slow Draco down and trying to persuade Draco to confide in him). If Dumbledore and Snape could get to the point at which the Stoppered Death potion simply wore off and Dumbledore died from the delayed curse on the ring, then Draco would be off the hook and the Unbreakable Vow would be neutralized. However, if Draco succeeded in pulling something off before the Stoppered Death potion wore off, then Snape would step in and appear to kill Dumbledore and try to save Draco from the dark side.
Why did Dumbledore call Harry during a school night to make the trip to the cave since Dumbledore told Harry a month earlier he believed he had found another Horcrux?  Dumbledore knew the protections on the Horcrux in the cave would be as deadly as the curse on the ring and that his time among the living would come to an end from the retrieval of that Horcrux.  So Dumbledore put off the trip to the cave as long as possible and used the time to track down other Horcrux clues, then when he realized from signs and symptoms that the “stopper” was loosening (just as Harry felt the Felix wearing off a few chapters earlier), he sent for Harry. The trip to the cave took place in late May, which would have been eleven months into the Stoppered Death potion and three weeks before the end of term. Dumbledore allowed Harry to accompany him because he wanted Harry to know how dangerously the Horcruxes were protected and also to have Harry with him to take the Horcrux in the event that he didn’t make it out of the cave.
Dumbledore didn’t know what he would find in the cave, but he knew the protections would be lethal and would hasten the expiration of the Stoppered Death potion if not kill him outright.  Again, when Hermione saw Dumbledore’s hand at the start of term feast in September, she said “"But there are some injuries you can't cure . . . old curses . . . and there are poisons without antidotes. . . ." (HBP8)  Dumbledore confirmed that a terrible curse upon the ring had damaged his hand, so we should consider that a hint that we were going to see a poison that had no antidote. The poisoned mead did have an antidote, so the poison in the cave must not have. Dumbledore said the poison in the cave wouldn’t kill right away because Voldemort would want to question the person who took the Horcrux. Would Voldemort go to all the trouble to make the cave Horcrux as difficult to reach and obtain as he did only to use a poison that could be neutralized with a bezoar or antidote? No. And Dumbledore knew Voldemort would use protections and traps that couldn't be foiled or couldn't be easily worked out.
Felix Felicis and Felix Culpa
Many people are trying to figure out two questions in particular about the night of Dumbledore's death.  1) Why did Dumbledore send Harry to his dormitory to get his Invisibility Cloak before they set out to for the cave since he had ordered Harry to have it with him at all times in the castle and since Harry did have with him in Dumbledore's office?   Dumbledore was ready to go with his cloak over his arm, so why didn't he ask him if he had it so the two of them could just leave?  2)  How is it that the DE raid happened on the very night Dumbledore and Harry made their trip to the sea cave? Was it just coincidence? Was Dumbledore set up? Did Dumbledore set it up himself?
I believe the answer to both questions is that Dumbledore took a swig of Felix Felicis before sending the note to Harry on the night they went to the cave. (Rereading a HogPro thread, I realized it was Professor_Mum, who said she wouldn't be surprised if Dumbledore had taken some Felix to help in the cave for Harry's benefit and if "Oho!" wasn’t a clue that Slughorn was standing in for Dumbledore, it likely indicated a "Slughorn-influenced DD.") The idea that we were seeing Felixed!Dumbledore in the cave seemed right when I read it, and I realized later that it could be used to explain the five minutes Dumbledore gave to Harry to get his Invisibility Cloak. Observations left by readers Meep and Rogueravenclaw (comments below) made me see there is much more to the theory, however, since it neatly explains how numerous important plot threads came together that night.  As Meep noted in her astute comment, "We've seen with Harry's use of Felix that "unconscious" objectives can be met by the potion, even if on the periphery."  
Moreover, I expect Rowling, the classics major who loves a twist, is playing on the idea of the felix culpa, or “fortunate fall.”  In a literary context, "felix culpa" describes a series of disastrous events that eventually lead to a happier outcome.   
As we saw when Harry took Felix to get the Horcrux memory, Felix does not predict or control other people or the environment; rather it nudges the user to maximize his or her abilities by reacting to the actions of other people in a step-by-step negotiation on the path toward the goal. And that is why Dumbledore, the greatest wizard of his age, would take a shot of Felix. Dumbledore had been on top of his game when he destroyed the Peverell ring, yet he sustained great damage to his wand hand and was “desperately injured” when he returned to Hogwarts to be patched up by Snape. He had no idea what deadly traps or protections would be in the cave.  With his damaged wand hand, his reflexes were slowed. And he would have Harry alongside him on the trip to the cave so would want the advantage of Felix to help him tweak circumstances in his favor for both their sakes.  It does not diminish Dumbledore’s greatness that he availed himself of "liquid luck."
The first hint to the reader that Dumbledore took Felix that night is in HBP when Harry mused about taking a some Felix to get into the RoR. Hermione talked him out of it:
"Luck can only get you so far, Harry. The situation with Slughorn was different; you always had the ability to persuade him, you just needed to tweak the circumstances a bit. Luck isn't enough to get you through a powerful enchantment, though. Don't go wasting the rest of that potion! You'll need all the luck you can get if Dumbledore takes you along with him . . ." HBP24
Just as Hermione handed us hints about the curse and the antidote-less poison, her statement is a foreshadowing that Felix would play a role in the trip to the cave although ironically, Harry was not taking it himself. Harry benefited from the Felix Dumbledore took and from the Felix he distributed among his friends at Hogwarts; Felix was critical to the night's events from two directions.
Dumbledore’s primary objectives were to retrieve what he hoped would be a Horcrux hidden in the sea cave, leave the school with extra protections, and return with Harry safely to Hogwarts. The influence of Felix wouldn’t have prompted him to abandon the trip because the cave contained a fake Horcrux. He wasn’t 100% certain that the cave contained a Horcrux, but he was certain it was the cave in which Tom Riddle had abused two orphans and he suspected something was in there heavily protected.  
When Harry took the Felix in order to get the memory from Slughorn, one of Harry's unconscious objectives was met when Harry, under his Invisibility Cloak, knocked into Ginny, setting off an argument that led to her break-up with Dean, which left Ginny free to form a relationship with Harry. This was not Harry's primary objective that evening and Felix didn't "inform" Harry that something lucky had just happened, but an unconscious objective was met by the potion since Harry wanted Ginny to be his girlfriend. In this same way, Dumbledore's unconscious objectives were being met that night even without his realizing it. 
On the night Dumbledore took the trip to the cave, he asked McGonagall and Flitwick to patrol in his absence "just in case," and asked Order members Remus Lupin and Bill Weasley to join them, which is evidence that Dumbledore intended to make the trip to the cave well before he sent the note to Harry since Bill and Remus had not been seen at the school during HBP. 
Under the influence of Felix, Dumbledore was prompted to give Harry five minutes to get his Invisibility Cloak even though he had reason to believe Harry had the cloak with him. Dumbledore would not have understood why this was a good idea any more than Harry had understood why he should take a detour past the vegetable patch on his way to Hagrid’s, but the five minutes gave Harry time to give instructions, the Marauder's Map, and his remaining Felix to his friends, actions that would prove critical to the night’s events. I initially thought the five minutes Felixed!Dumbledore's gave Harry was lucky in the sense that it allowed Harry to give instructions and Felix to his friends "just in case," which enabled them to know that Draco brought DE's into the school and kept the students alive during the fight. This would have been a conscious objective served since Dumbledore wanted the school protected that night and left a small patrol of his own "just in case." It was Meep who made me see that Dumbledore's unconscious objects were also being served with the "five minutes," since the Felixed!students made the difference in holding back the DE's long enough to let Dumbledore talk to Draco alone and to let Snape reach the Tower in time.
Draco was celebrating the repaired Vanishing Cabinet at around 8:45 PM when Harry received the note from Dumbledore, so Dumbledore hadn’t planned the trip to the cave that night to give Draco an opportunity to stage a DE raid or because he knew Draco was about to stage one. Dumbledore would not have vacated the school had he known the DE’s would be entering in his absence, and the fact that he didn’t put more teachers on patrol who were at Hogwarts (Hagrid, Slughorn, Sprout, etc.) is evidence that he felt confident with the protections in place. The small patrol he formed before leaving was a precaution because he knew Draco had only a few weeks left and might be getting desperate. I do not believe for a minute that Dumbledore knew Draco would be bringing DE’s into the school that night.
When Dumbledore and Harry left for the cave, Imperiused Rosmerta, throwing some customers out the door, spotted them and reported this information to Draco. What happened with the DE raid and Dark Mark set over the AstronomyTower later that night was opportunistic on Draco’s part. The timeline suggests Draco would have known Dumbledore was in Hogsmeade around 9:00 PM, but Hermione said Flitwick didn’t run into the dungeon for Snape until nearly midnight.  From that, I conclude that a DE raid had been hastily put together once Draco knew Dumbledore would be at the Hog's Head for the evening.  Also, there was no way for Draco and the DE's to know that Dumbledore was far away, incapacitated mentally and physically from the green potion in the cave. Moreover, there was no way for anyone to know whether Dumbledore would be able get back to Hogwarts that night since Harry, an inexperienced Apparator, might have left them both splinched on the coast of England in his first attempt at a side-along Apparation.
As Rogueravenclaw noted in the comments, Rosmerta’s seeing Dumbledore was a catalyst for the night’s actions at the school that realized Dumbledore’s “unconscious” objectives regarding Draco and Snape, so Felix wouldn’t have prompted Dumbledore to seek a different route through Hogsmeade to avoid Rosmerta. Dumbledore needed the events of the night to play out as they did for his unconscious objectives to be met.
The peculiar "five minutes" given to Harry to return to GryffindorTower meant Ron, Ginny, and Neville were positioned outside the RoR, which is how they knew Draco had found a way to let the DE’s into the school. As the students followed Draco, they ran into McGonagall, Flitwick, Lupin, and Bill, who had no idea DE's were in the castle. As Lupin said,
“Luckily,” said Lupin hoarsely, “Ron, Ginny, and Neville ran into us almost immediately and told us what had happened. We found the Death Eaters minutes later, heading in the direction of the Astronomy Tower.” HBP 29
Luckily, indeed. If not for the five minutes Dumbledore gave Harry, the staff wouldn't have known to look for the DE's, Flitwick wouldn't have been sent to get Snape, and ultimately Dumbledore would have been killed by a DE, resulting in Snape's death from the UV. In fact I believe Bellatrix was helping Draco all year and wanted the DE's to back him up precisely so that if Draco failed, at least Snape would die; that's why she had been training Draco in Occlumency--so that Snape would not find out what Draco was doing until it was too late for Snape to save his own life.
As Ginny said, “Harry, if we hadn’t had your Felix potion, I think we’d all have been killed, but everything seemed to just miss us.” (HBP29)  Not only did Harry's remaining Felix enable his friends to live through the fight with the DE's, they were central to supporting McGonagall, Lupin, and Bill in holding the DE's back long enough to realize Dumbledore's unconscious objectives regarding Draco and Snape. Of the four teachers placed on patrol, Flitwick had been stunned before the fight began and Bill went down during the fight; without the Felixed!Students, McGonagall and Lupin would likely have died trying to fight a half-dozen DE's, so the DE's would have been on the Tower before Dumbledore could talk to Draco alone and would have killed Dumbledore before Snape could get there, resulting in Snape's death from the UV.
The influence of Felix explains the halting/intuitive way Dumbledore moved around the cave—seeming not to have been there and yet seeming to know what to do and where to go—and explains how Dumbledore knew that the poison would not kill him right away (just as Felix had “told” Harry that Slughorn wouldn’t remember giving him the Horcrux memory the next day).  There was a direct mention of Felix in the cave scene when Harry wondered if his friends had taken the Felix Felicis he left them with. The exclamation “Oho” Dumbledore used in the cave is a big clue to Dumbledore’s use of Felix that night because it’s an expression Slughorn used three times during Harry's first NEWT potions class. The third and last time Slughorn said "Oho!" in HBP was when he introduced the students to Felix Felicis. At some point, I expect Slughorn to confirm Dumbledore’s use of Felix.  
The Horcrux in the cave turned out to be a fake, and Dumbledore's life ended on the AstronomyTower upon his return to the school. This doesn't square with the luck we associate with Felix Felicis, but in the context of the felix culpa or "fortunate fall," the most distressing events of the night---Dumbledore's death and literal fall from the Tower, the fake Horcrux, Bill Weasley's injuries, the undermining of confidence in Dumbledore’s judgment, the escape of Dumbledore's apparent killer and accomplices, etc.---were not the disasters they appeared to be since Dumbledore’s ultimate objective, to vanquish Voldemort, was being furthered. There was a cost, but a relatively minor one when examined closely.  
Despite finding the fake locket, it was still an advantage to Harry that Dumbledore went to the cave since if Dumbledore had died before the cave trip, the trio might have identified the cave as a possible Horcrux location and made the trip, quite likely resulting in Harry's death. The message in the locket from RAB is a huge clue for the trio, so they'll be able to realize that the heavy gold locket at 12GP is Slytherin's locket.  Harry will still need to find and destroy the locket Horcrux, but there do not appear to be any necklace-type curses on it since everyone at 12GP handled it and tried to open it without harm to themselves. 
Bill Weasley’s disfigurement was not as unlucky as it seemed since he suffered no mortal wounds, he was not turned into a werewolf, and his personality was upbeat; moreover because of his injuries, Molly and Fleur were reconciled by Fleur's demonstration of abiding love for Bill no matter what future he faced, prompting Molly to offer Auntie Muriel’s goblin-made tiara for the wedding, which offer, I believe, will lead to the discovery of the mystery Gryffindor/Ravenclaw Horcrux:
Dumbledore had wanted to talk to Draco all year but knew he couldn't without endangering the boy's life, so in the context of the fortunate fall, Dumbledore was able to speak personally to Draco, to prevent him from becoming a killer, to make him see that turning from dark magic is the right choice, and to assure Draco he trusted Severus Snape.  As a result of his confrontation with Dumbledore,  Draco knows he isn't a killer and doesn't want to be associated with Fenrir Greyback and the DE's. Most importantly, Draco knows that help is available to him through the OotP.  Dumbledore had not known what to do regarding Draco’s task other than take the trip to the cave, which would very likely unstopper his death, allowing Snape to later claim to have killed Dumbledore (just as Snape had taken credit for Sirius's death) and getting Draco off the hook temporarily. However, that scenario wouldn’t have afforded any opportunity to talk to Draco, and if one of the DE's had been forced to kill Dumbledore on the Tower, Snape would have died from the UV, and Draco would not have Snape as a protector when he faced Voldemort for his failure to succeed.  Merlin at MuggleMatters pointed out that Snape did fulfil the UV because he watched over Draco, protected him from harm, and carried out the deed, although Snape fulfilled the UV by preventing Draco from succeeding.
The events of the night saved Snape from death by the UV and made it appear as if Snape killed Dumbledore cold-bloodedly, which will strengthen his credentials with Voldemort.  Even the sense among the Hogwarts staff and Order members that Dumbledore had made a grave mistake in trusting Snape will work to Snape's advantage by removing any lingering doubts Voldemort may have; the MoM officials were at the school that night, so word would have traveled quickly that Snape was considered an unequivocal enemy. Voldemort's increased confidence in Snape will provide an opening for him to clear a path for Harry in some way that he wouldn't have been able to do had Dumbledore merely died that night from the cave poison.  And Snape's soul was not damaged by the AK since Dumbledore was “already dead.”   
There was one Felixed moment in the cave that I expect will bring about a Harry-Voldemort confrontation: Harry's blood tribute. Dumbledore said the poison wouldn't kill immediately because Voldemort would want to question the person who emptied that basin.  But how would Voldemort be able to identify the person? The blood tribute. The blood traces left on the wall will be Voldemort's means via magic that will reveal the identity of the wizard who was there. Dumbledore’s blood was left on the outer wall, and Harry's on the inner wall. Voldemort will not think to check the inner wall at first because he has a history of forgetting important things, but at some point he will check. Finding the deceased Dumbledore's blood might lead to close questioning of Snape. Finding Harry's blood will spur Voldemort to rush to his other Horcruxes, two of which I believe are at the school. Harry's and Voldemort's paths will converge at the school, where I believe the secret passageways from Hogwarts to Hogsmeade will be key to reaching and destroying the Hufflepuff Cup and may involve Wormtail's life debt to Harry: 
So as unlucky as the events appeared to be on the surface, the outcomes of that night favor Harry in his quest to destroy the Horcruxes and vanquish Voldemort.  A truly fortunate fall if indeed Felix Felicis is involved as appears.
Hogwarts may not be the location of the final confrontation, however, which I'm beginning to think will happen in the Deparment of Mysteries because of the Veil and Love Room, especially if Voldemort goes there to find a Time-Turner to get his Horcruxes back (and may even be set up to do so in a reversal of OP).  Dumbledore described love as “a force that is at once more wonderful and more terrible than death." And you cannot Apparate or Disapparate in the DoM.
I agree with many others that only Fawkes could convince Harry of Snape's loyalty to Dumbledore and that at some point, the Stoppered Death information will be given to Harry from Snape himself after the intervention of Fawkes convinces Harry that Snape had been loyal to Dumbledore all along. 
Further Evidence that Snape is loyal to Dumbledore despite his actions that night
McGonagall sent Flitwick to get Snape, and Flitwick went directly to Snape’s dungeon office, so they all expected Snape to be in his office; clearly Sbape did not know the school would be attacked that night any more than Sprout, Slughorn, and Hagrid did.  He wouldn't have been in his office if he had known about the DE raid because he couldn't have expected Draco would be able to kill Dumbledore, and Draco's failure would kill Snape via the UV.  As Hermione said:
”It was nearly midnight when Professor Flitwick came sprinting down into the dungeons. He was shouting about Death Eaters in the castle, I don’t think he really registered that Luna and I were there at all, he just burst his way into Snape’s office and we heard him saying that Snape had to go back with him and help and then we heard a loud thump and Snape came hurtling out and he saw us and —and—“HBP 29
Snape didn’t know Hermione and Luna were outside his door, so if Snape were loyal to Voldemort, he could have killed Flitwick to get rid of one more wizard willing to fight Voldemort.  But instead of harming Flitwick, Snape stunned him since Snape had not been told that a fight was underway, only that DE's were in the school. When Snape ran out of his office and saw the girls, he told the girls to go into his office and take care of Flitwick. 
That is odd given that Snape told the Black sisters Harry was mediocre and had thwarted Voldemort by sheer luck and more talented friends. So why didn’t Snape kill Hermione, the most brilliant of Harry’s helpful, talented friends?  Snape told the DE’s to leave Harry for the Dark Lord, but is it likely Voldemort wanted Harry’s friends spared? A faithful DE would have wanted to kill Luna as well since she had helped thwart the attempt to get the prophesy and her father had published an account of Voldemort’s rebirth, his humiliation when Harry escaped, and the return of his DE’s, whose names were published. There was no one in the dungeon except for Hermione, Luna, Snape, and the stunned Flitwick, and Snape must have known that he would be leaving the school that night for good after unstoppering Dumbledore or else dying from the UV. But he didn’t kill them. 
When Snape reached the fight, he ran to the Tower, fulfilled his promise to Dumbledore, then hustled Draco and the DE’s out of the castle, sparing Harry, preventing him from using Unforgivables, and warning him to keep his mind closed and mouth shut (i.e., practice Occlumency and learn nonverbal spell casting).  And as Merlin at reminded me, Snape didn't kidnap Harry as he could have.
What's wrong with Dumbledore having Snape just kill him to advance military objectives?
I emphatically believe Dumbledore would never ask Snape or anyone else to commit an act that would irreparably tear his or her soul. It’s not an “out” to say that Snape’s soul was already damaged from his time as a DE. I doubt Dumbledore would see it that way.
I believe the consensus among readers is that killing in self-defense would not tear the soul because it wouldn’t cross the line into a “supreme act of evil.”  But the three Unforgivable Curses (torture, control, death by AK) each earn a life sentence in Azkaban, and, tellingly, there is no death penalty in the Potterverse. It tells me a lot that even DE’s who have committed the Unforgivable Curses in abundance are not put to death. Dumbledore’s friend Alastor Moody, greatest of Aurors, refused to use Unforgivables even when given permission; he brought his DE in alive if possible even though it cost him a leg, an eye, and part of his nose. These things give more credence to the idea that Dumbledore was not “alive” in HBP in the way that, say, Horace Slughorn was alive; because if Dumbledore had been truly alive that night, he would have been instructing Harry and Snape to kill him and that would be a reversal of what Rowling has been telling us about Dumbledore and his values. The only way Dumbledore’s order to Harry to administer the poison and to Snape to cast an AK at him can be reconciled is that he was “already dead” and that Harry and Snape "unstoppered" him. 
If Dumbledore and Harry had been allowed to return to Hogwarts without DE interference, I am sure Dumbledore would have died soon afterwards from the combined effects of the ring curse, the Stoppered Death potion wearing off, and the cave poison. But since the DE’s were in the school, the alternate plan had to be worked, with Snape taking over from Draco and at least appearing to kill Dumbledore on the Tower. So Snape unstoppered Dumbledore’s death on the Tower using a real Avada Kedavra curse on Dumbledore’s orders. And since Dumbledore had technically been dead since the previous July, it was not a murder but rather pulling the stopper out of Dumbledore's magically extended life, allowing Dumbledore’s death to proceed.
Given this theory, why did Dumbledore want to see Snape even before knowing about the Dark Mark over the AstronomyTower? Because it was time to commence "Operation Save Draco" by having Snape be in a position to later take credit for killing Dumbledore. Pat over on the HogPro forum also pointed out to me that Dumbledore may have wanted to have a conversation with Snape and Harry together to ask them to put aside their differences and animosity and work together to defeat Voldemort. I think she’s right.

Must read essay: 'Good Snape' is not a 'Square Circle' By H.M. Ketcham

“Something of Ravenclaw’s or Gryffindor’s”

“Something of Ravenclaw’s or Gryffindor’s”
We saw in HBP that Hepzibah Smith was distantly related to Helga Hufflepuff and that Hufflepuff’s gold cup was in her possession. We also saw that Salazar Slytherin’s line ends with T.M. Riddle/Lord Voldemort through the Gaunt family, which was in possession of Slytherin’s gold locket and a Slytherin family heirloom, the Peverell ring. But we haven’t been given direct information identifying the family or families that descend from Rowena Ravenclaw or Godric Gryffindor.
I have a hunch that the Fortescues are in the Ravenclaw bloodline and that Florean Fortescue’s disappearance has something to do with a Ravenclaw founder relic or family heirloom.  I also have a hunch that Great-Auntie Muriel’s goblin-made tiara is part of the story.
The Fortescue/Ravenclaw Connection:
The majority of portraits of dead headmasters and headmistresses in Dumbledore's office hardly ever speak and only a few are described in any detail. I've skimmed the books looking for passages involving these portraits, and mostly they are noted as snoozing or snoring with no other details given. Unless a portrait has a plot function, Rowling doesn't zoom in on them, and the more important they are, the more fully they are described. 
In the scene following Harry’s dream of the snake attack on Arthur in OP22, Dumbledore wanted Phineas to ask Sirius if the Weasley children could stay at 12 Grimmauld Place, but Phineas first pretended to be asleep and then balked at running the errand. Several portraits spoke in that scene:
Harry recognized Armando Dippet from the diary memory; Dippet was described in this scene as a frail-looking wizard who reminded Phineas that portraits are honor-bound to serve the present headmaster. He was spotted once more.
An unnamed gimlet-eyed witch holding a wand similar to a birch rod asked Dumbledore if he wanted her to persuade Phineas.
Phineas was described as a clever-looking wizard with a pointed beard who was painted wearing the Slytherin colors of green and silver standing behind a Slytherin banner. Harry recognized his voice as being the same one that spoke to him at the beginning of OP from the empty portrait in his bedroom at 12 Grimmauld Place. Phineas made snarky comments in other scenes in OP and snorted in disrespect when Dumbledore agreed to take Harry to the cave in HBP.
Everard was described as a sallow-faced wizard with short, black bangs who was painted in front of a velvet backdrop; he went to his other portrait in the Ministry of Magic to sound the alarm for Arthur. He made a return appearance at the end of HBP to tell McGonagall that the MoM had received the news of Dumbledore’s death and would be arriving shortly.
Dilys was described as an elderly witch with long silver ringlets who was painted on a handsome leather armchair; she went to her other portrait at St. Mungo’s to see Arthur being taken in weak but alive. She later winked at Harry from her portrait at St. Mungo’s and appeared to be counting the Weasley children as they walked past on their way to visit Arthur.
One additional portrait was highlighted in this scene. The wizard in the portrait isn’t named in this scene, but the “corpulent, red-nosed” wizard was highlighted three times in OP and once in HBP. It appears that the corpulent, red-nosed wizard in all of the scenes is Headmaster Fortescue.
In OP, when Phineas appeared reluctant to visit Sirius to ask if the Weasleys could stay with him to be near St. Mungo’s:
“Insubordination, Sir!" roared a corpulent, red-nosed wizard, brandishing his fists. "Dereliction of duty!" (OP22, p. 473)
In OP, when Harry was being confronted in Dumbledore’s office after the DA’s meeting had been raided, it was learned that Willy Widdershins overheard the first DA meeting at the Hog’s Head and reported it to Umbridge to avoid being prosecuted for causing toilets to regurgitate:
"Blatant corruption!" roared the portrait of the corpulent, red-nosed wizard on the wall behind Dumbledore's desk. "The ministry did not cut deals with petty criminals in my day, no sir, they did not!"
"Thank you, Fortescue, that will do," said Dumbledore. (OP27, p. 614)
At the end of OP, when Dumbledore sent Harry back to his office alone using a portkey, the wizard spoke to him again:
"I hope this means," said the corpulent, red-nosed wizard who hung on the wall behind Dumbledore's desk, "that Dumbledore will soon be back with us?"
Harry turned. The wizard was surveying him with great interest. Harry nodded. [snip]
"Oh good," said the wizard. "It has been very dull without him, very dull indeed."
He settled himself on the thronelike chair on which he had been painted and smiled benignly upon Harry.
"Dumbledore thinks very highly of you, as I am sure you know," he said comfortably. "Oh yes. Holds you in great esteem." (OP37, p. 822)
In HBP, after Harry and Dumbledore reviewed the Horcrux memory Harry had just obtained from Slughorn, the wizard was again highlighted trying to hear their very interesting conversation about Horcruxes:
“Harry suddenly noticed that every single one of the old headmasters and headmistresses in the portraits around the walls was awake and listening in on their conversation. A corpulent, red-nosed wizard had actually taken out an ear trumpet.” (HBP23, p. 499)
This portrait of Headmaster Fortescue interests me for several reasons:
*Rowling doesn’t describe the appearance of a particular headmaster or headmistress or throw the spotlight on them more than once in any meaningful way unless they have a function in the story. Phineas, Dilys, and Everard are minor characters but they provided important information as errand-runners during critical moments. Headmaster Fortescue has been mentioned four times, yet he doesn’t have an obvious purpose in the story relative to the attention Rowling has given him.
*Fortescue is described as corpulent and red-nosed, a description close to the "corpulent, red-cheeked" complexion and body type associated in the medieval theory of humours with the element of air. Rowling assigned the element of air to Ravenclaw. According to one website, the personality traits associated with this humour are amorous, happy, generous, optimistic, and courageous, which fits with the characters of the Headmaster Fortescue and his probable descendant Florean Fortescue, owner of the Diagon Alley ice cream parlor.
*Fortescue is a surname with a known date of origin. Sir Richard Le Forte was a leader in the Norman army at Hastings. He protected Duke William ("the Conqueror") by holding a large shield or escu in front of him. When William prevailed, Sir Richard changed his surname to Richard Fort Escu, which means “strong shield.” Richard’s son was granted lands in Devon by a grateful William for the family’s distinguished service to him, making the family instant landed aristocracy in England. The year (1066) was fewer than 100 years after the founding of Hogwarts School of Witchcraft and Wizardry.
*Headmaster Fortescue was painted sitting on a “thronelike chair,” which seems to hint that he was a member of a noble family. I can’t help but think of the Noble House of Gaunt, which referred to Slytherin’s line. Assuming the Fortescues are in Ravenclaw’s direct bloodline, we see that Ravenclaw’s line didn’t descend into the psychopathic squalor of Slytherin’s, but Florean Fortescue is a small business owner, not a member of the aristocracy. And true to Ravenclaw House’s reputation for having the most intelligent students, Florean is a scholar even though he made ice cream for a living. 
*Florean Fortescue helped Harry with his History of Magic homework at the beginning of Prizoner of Azkaban when Harry was staying at the Leaky Cauldron. Florean knew a great deal about medieval witch hunts and burnings and also gave Harry free ice cream sundaes every 30 minutes. Early in Half-Blood Prince, Bill Weasley reported that Florean had been dragged off by Death Eaters from the look of his ice cream place. Florean was described as a good man who must have done something to upset them.
*The portrait of Headmaster Fortescue is directly behind Dumbledore’s desk. On a shelf above Dumbledore’s desk is the Sorting Hat, and next to the Sorting Hat is a glass case holding Godric Gryffindor’s sword. These are the only two known Gryffindor relics, and Horcruxes are largely about relics of the four founders of Hogwarts. In the HBP chapter in which Harry and Dumbledore reviewed Slughorn’s true Horcrux memory, Rowling focused on only one portrait—Headmaster Fortescue—who pulled out an ear trumpet to better hear their interesting conversation. 
*I believe the placement of the Fortescue portrait near the Gryffindor relics, the physical description of Headmaster Fortescue linking him to the element of air, and the thronelike chair on which Headmaster Fortescue was painted are hints that the Fortescues are in Rowena Ravenclaw’s bloodline. 
The Weasley/Gryffindor Connection
This one is much easier since there are plenty of clues to tie the Weasleys to Godric Gryffindor and they're all on the surface. The pure-blood Weasleys are predictably sorted into Gryffindor house, they have the red-hair and choleric temperament associated in medieval humour theory with the element of fire (choleric people are sometimes called bilious, and Ron mentioned having an Uncle Bilius), there are several links to the Weasleys and ferocious, fire-breathing animals (Charlie works with dragons, Bill wears dragon-skin boots, the twins wear dragon-skin jackets), and most importantly, they have royal/Arthurian names (Arthur, William, Charles, Percy Ignatius, George, Frederick, Ronald, and Ginevra). But this doesn’t mean that only the Weasleys are descended from Gryffindor, and I have a hunch that when Rowling seemed to agree (hesitantly) in an interview that Harry was not the Heir of Gryffindor, she meant he wasn’t the last surviving heir as Tom Riddle is Slytherin’s last surviving heir. (There’s still room for Harry to be in the Gryffindor’s bloodline. James and Lily were living in Godric’s Hollow after all. But I have a hunch—prompted by Charles Potter’s marriage to Dorea Black on the BFT—that Harry may somehow carry the blood of all four founders. That would tie into the Sorting Hat’s songs about house unity because Harry does need to be the unifier in this fractured world. However, it would mean that a Slytherin male had fathered an illegitimate child at some point since both Dumbledore and Voldemort believed Tom Marvolo Riddle to be the last of the line.)
So where’s the connection?
The only two times tiaras were mentioned in the six books occurred in the last few chapters of HBP: Harry used a tarnished tiara to mark the hiding spot for the Prince’s textbook in the Room of Requirement and Molly mentioned her Great-Auntie Muriel’s goblin-made tiara. In the absence of any other strong clues to point the way, a tiara is the best candidate for the object of the mystery Horcrux. Is it possible that Great-Auntie Muriel could own Rowena Ravenclaw’s tiara and not know its provenance (I don’t think Godric Gryffindor would have worn a tiara)? That seems unlikely. Yet Great-Auntie Muriel’s goblin-made tiara is interesting because Tom Riddle was visiting Hepzibah Smith to make an improved offer on her goblin-made armor, so maybe the “goblin-made” reference is a clue that we should be paying attention to this tiara. I can’t think of anything else in the books referred to as goblin-made. “Goblin-made” suggests it’s old and valuable, so it could be a Ravenclaw or Gryffindor family heirloom without being a true founder relic (just as the Peverell ring was a Slytherin family heirloom but not a true Slytherin relic).  And since Ravenclaw was also described as "fair," a beautiful adornment like a tiara that would encircle the mind is a very plausible Ravenclaw relic even it pertains to her decendants and not to Rowena herself
In the Horcrux hunt, we’re looking for “something of Ravenclaw’s or Gryffindor’s,” which seems to imply that it will be one or the other, but what if that phrase is itself a clue that the Horcrux will be both in some way? Just because the Slytherin line petered out into one remaining person (Riddle/Voldemort) doesn’t mean the same is true of either the Gryffindor or Ravenclaw bloodlines. For all we know, Godric Gryffindor and Rowena Ravenclaw each had five children and each child founded a series of multi-branching families over the last 1,000 years. The pure-blood families are all related to each other as we’ve been told and as we can see from a little bit of Black ancestry from the Black Family Tree. Molly’s reference to “our” Great-Auntie Muriel, might be suggesting that both Molly and Arthur have blood ties (however distant) to Muriel. After all, Hepzibah Smith only claimed to be distantly related to Helga Hufflepuff, not the last of her line as Marvolo claimed the Gaunts to be.
We don’t know how Muriel is related to Molly and Arthur, but since Ginny is the first Weasley daughter to be born in several generations (surely a clue for something in the story and we haven’t seen anything yet), it’s not a long-shot that Muriel married a Weasley, and it’s entirely possible that Muriel was a Fortescue. We’ve heard enough times that all the old wizarding families are related to each other, and Muriel as a Fortescue Ravenclaw married to a Weasley Gryffindor would help us to solve the identity of the mystery Horcrux, which, in a way, would be “something of Ravenclaw’s and Gryffindor’s.” If the relation between Arthur and Molly to Florean Fortescue is fairly distant, then we wouldn’t have necessarily heard about it even when Florean’s disappearance was being discussed in the Weasley kitchen. They never discuss Septimus Weasley’s marriage into the Black family even though Sirius and his relatives are discussed often enough. I’d say it’s a fair shot that the goblin-made tiara has connections to both Gryffindor and Ravenclaw bloodlines. 
So where could this be going?
Aren’t we looking for “something of Ravenclaw’s or Gryffindor’s” that was made into a Horcrux a long time ago? Not necessarily. We know Voldemort had the Peverell ring, diary, Hufflepuff cup, and Slytherin locket Horcruxes under his belt by circa 1947-48.  And we know Dumbledore believed Voldemort was planning to make his sixth Horcrux at Godric’s Hollow, but Dumbledore was making an educated guess and didn’t pretend to be certain about that. We frankly have no idea when Voldemort made the fifth Horcrux or even if he had made five Horcruxes by October 31, 1981. 
Theory 1. Certainly someone in the family would have noticed if a valuable heirloom had gone missing years ago.  But if the goblin-made tiara is a Ravenclaw family heirloom, and Voldemort learned about it years ago and turned it into a Horcrux, does it necessarily follow that he stole it from the family? He did indeed steal away the locket, cup, and ring but perhaps he considered that his next Horcrux would be safest left with the family guarding it. Suspicion fell on him when Hepzibah Smith’s most prized relics were discovered missing and the young man from Borgin and Burkes who had been shown them only days before her death had promptly disappeared after her death. Hokey took the blame for Hepzibah’s death, but the theft of the cup and locket was an unsolved crime. Voldemort knew from Hepzibah that her family would never sell the cup, so maybe he reasoned that an heirloom Horcrux like the tiara would be best protected if he left it where it was.  Once he had taken the cup, ring, and locket, he needed to find safe places to hide them. By leaving the tiara in place, he eliminated the problem of finding a hiding place for it but still could be assured of its safety; moreover, if he managed to turn it into a Horcrux without anyone in the family catching on, no one would ever suspect what he had done to it.
So why then would Florean Fortescue need to be hauled off by Death Eaters in 1996? Perhaps Voldemort decided he wanted to put the tiara Horcrux in another location or check on it and learned that it had been moved, so he needed a family member to get it, and Florean Fortescue was easy to grab because he was out in the open in Diagon Alley. But that begs the question: why would Voldemort care that it had moved to another family member so long as it was still in the family and protected? And from a plot point of view, this theory is problematic because Harry has to find and destroy the Horcruxes before confronting Voldemort, and he won’t be able to do that if Voldemort had already started shifting them to new locations at the beginning of HBP.  On the other hand, perhaps he did check the locations of his Horcruxes in the summer of 1996 just to be sure they were still where he left them, and he discovered that the tiara had been transferred to a new keeper (he could have known just by looking in the cave that the green potion was untouched, so he wouldn't have needed to empty the basin and see the actual locket.).
Theory 2. An alternative theory is that Voldemort made a seventh Horcrux with the death of Amelia Bones and forced Florean to get the tiara kept by Muriel to use for this new Horcrux. I do believe with others that Voldemort is so dehumanized at this point that he could only make another Horcrux at great cost to himself, but he does place great importance on the magical power of seven and knew the diary has been destroyed. He might want another Horcrux to replace the diary.  On the other hand, the soul fragment from the diary wasn't destroyed but merely released from its anchor and probably went behind the Veil, so his soul was still in seven parts despite the destruction of the diary Horcrux.  The only difference is that one fragment is no longer anchored to the earth. But the main problem with this theory is that Harry would have to figure out that there’s an additional Horcrux out there. If Molly asks to borrow the goblin-made tiara for Bill and Fleur’s wedding, and Muriel discovers it’s missing but was last seen shortly before Florean disappeared, the trio may put it together quickly and realize that Fortescue was snatched to get a “trophy” item from Ravenclaw’s family line.  One additional Horcrux would not be a super complication, but if the tiara is Horcrux #7, then that leaves us still trying to identify the “something of Ravenclaw’s or Gryffindor’s” mystery Horcrux.  Rowling has a lot of ground to cover in Book 7 with the Horcrux hunt, Horcrux destruction, expected warfare with giants, werewolves, goblins, elves, Dementors, wizards, etc., ultimate confrontation with Voldemort, backstory to fill about Dumbledore, Lily, James, etc., and an extra Horcrux would be an unnecessary distraction and page-eater, so it's not likely to happen. 
Theory 3. However, what if Voldemort had only made five Horcruxes when he entered Godric’s Hollow in 1981, and he made the sixth Horcrux with the goblin-made tiara in 1996? If he made the cup and locket Horcruxes in the late 1940’s and planned to make his last Horcrux from Harry’s death in 1981 per Dumbledore’s guess, he was not in a rush to get seven Horcruxes made early on, so it is not a given that he had made #5 before 1981. Maybe he planned to use Harry’s death to make Horcrux #5, not #6. This scenario would mean that there would still only be six Horcruxes in total, three of them destroyed, and the “something of Ravenclaw’s or Gryffindor’s” will be easy to identify if indeed the Ravenclaw heirloom goblin-made tiara is found to be missing early in Book 7 and Florean’s disappearance turns out to be near the time it was last seen (so the trio will be able to put it all together). Rowling did say in an interview that on the subject of the remaining Horcruxes, Dumbledore’s guesses were not very far wide of the mark, and there is nothing about a Ravenclaw Horcrux made in 1996 to contradict that statement or Dumbledore’s guesswork. So if the “something of Ravenclaw’s or Gryffindor’s” is the goblin-made tiara, then the mystery Horcrux will be relatively easy to identify. Whether it will be easy to locate is another question unless it was placed for temporary safe-keeping in the Room of Requirement and Harry inadvertently used it to mark the location of his textbook.
This may seem too pat, but Rowling is in the home stretch now, and she has to connect plot threads in order to pull everything together in one final book, so for plotting economy, there is reason for Great-Auntie Muriel’s goblin-made tiara and the tiara in the Room of Requirement to be the same tiara. What better place to store the tiara than in a magical room the size of a Cathedral containing thousands and thousands of motley objects hidden there by generations of Hogwarts staff, students, and castle elves? According to Ravenclaw’s Famous Wizard card, she is best remembered for her intelligence and creativity and is thought to have developed the school’s ever-changing floor plan. She sounds like a good candidate to have developed the school’s ever-changing magical room as well, so wouldn’t there be a nice little tie-in with a Ravenclaw Horcrux hidden in an extraordinary room that Rowena created? 
Whether the goblin-made tiara is a Ravenclaw or Gryffindor or both heirloom remains to be seen, but the plot lines will be knitting together in Book 7, and many of us expect Fleur and Bill's wedding will be marred in some disastrous way.  The discovery that the tiara the bride was to wear is missing could be a foreshadowing of this.

The Hufflepuff Cup is in the Hogwarts Trophy Room Transfigured into the Medal for Magical Merit

I’ve been looking at a pattern of clues in the six Harry Potter books, namely a series of interweaving and overlapping references to Transfiguration magic, secret passages/the Marauder’s Map, and trophies. Putting them all together, I believe they may be clues that the Helga Hufflepuff’s golden cup is in the trophy room at Hogwarts but Transfigured into TM Riddle’s Medal for Magical Merit (note: I am not referring to the Award for Special Services to the School, but a separate award that was only mentioned once). I’m not 100% certain this is the correct conclusion, but there is a pattern, and a good case can be made for the theory.

The clues in the breadcrumb trail supporting this theory are numbered below; my commentary for each clue is asterisked (*), and my summary is at the end: 

1. Harry’s first Transfiguration textbook was A beginner’s Guide to Transfiguration by Emeric Switch (PS5).

*Transfiguration is magic that changes one object into something else (such as Transfiguring a match into a needle or using a Switching Spell to change a dragon’s teeth into wine gums). The HP Lexicon lists the many uses and types of Transfiguration used in the HP books (

*Emeric is a variation of the name Almeric. Almeric comes from the Old Germanic name Amaliricus, which is derived from "amal" (work) and "ric" (power, rule, ruler, kingdom).

*Switch means to exchange one thing for another.

2. Helga Hufflepuff is described in the Sorting Hat’s songs in Philosopher’s Stone and Goblet of Fire as prizing hard work.

Those patient Hufflepuffs are true 
And unafraid of toil; (PS7)

For Hufflepuff, hard workers were
Most worthy of admission;(GF12)

*The name Hufflepuff suggests toil and exertion (huffing and puffing), and she valued "hard workers" and students "unafraid of toil."  These call to mind the name Emeric (derived from "amal" (work) and "ric" (power, rule, etc.)).


3. In the first description of Professor Binn’s History of Magic class, "Binns droned on and on while they scribbled down names and dates, and got Emeric the Evil and Uric the Oddball mixed up." (PS8)

*Emeric Switch and Emeric the Evil are not the same person, but the name Emeric is used only twice in the books (this class reference and the textbook author) and appear fairly close together (PS5 and PS8). Moreover, in the second usage of the name, information pertaining to an evil character (Emeric the Evil) is switched with information pertaining to a good one (Uric the Oddball), which is an allusion to Transfiguration magic (switching, exchanging, inversion, etc.).


4. The first mention of the Hogwart’s trophy room comes in PS9 when Draco Malfoy challenged Harry to a wizard’s duel at midnight in the trophy room, chosen because it was never locked. On the same page, Fred and George mention that Lee Jordan thought he’d found a new secret passageway out of the school; the twins thought it might be the one behind the statue of Gregory the Smarmy that they found during their first week at Hogwarts. (PS9)

*The Wizarding duel proposed by Draco was itself a set-up for a deceitful switch since Draco’s intention was to tip-off Filch so that Filch would find Harry and Ron in the trophy room after curfew.

*This is the first mention of secret passages out of Hogwarts. When Rowling mentions secret passageways or the Marauder’s Map, a reference to the trophy room is often very close to it.

*The trophy room is never locked, which means anyone would be able to access it at any time and no one regards the objects in it as very important. It’s a perfect place to hide something of great value that has been disguised to look like an object of low value.


5. Hermione, not yet friends with Harry and Ron, followed them out of the Gryffindor common room the night of the wizard’s duel, hissing like a goose, and trying to dissuade them from going to the trophy room by saying that if caught, they would lose all the points she had gained from McGonagall for knowing about switching spells ("Don’t you care about Gryffindor, do you only care about yourselves, I don’t want Slytherin to win the house cup, and you’ll lose all the points I got from Professor McGonagall for knowing all about Switching Spells.") (PS9)

*Hermione makes a direct reference to Switching Spells and the Transfiguration teacher during a conversation about the trophy room.


6. We got our first look at the trophy room when Harry, Ron, Hermione, and Neville entered the room: "They sped up a staircase to the third floor and tiptoed toward the trophy room. Malfoy and Crabbe weren’t there yet. The crystal trophy cases glimmered where the moonlight caught them. Cups, shields, plates, and statues winked silver and gold in the darkness." (PS9)

*The trophy room is crowded with various objects from Hogwarts’s long history, so hiding an additional trophy at Hogwarts would be easy.

*The trophy room is on the third floor (the same floor as the statue of the one-eyed, humpbacked witch that we learn in PA opens to reveal the secret passageway leading to the cellar of Honeydukes).


7. Lucius Malfoy picked up Ginny Weasley’s A Beginner’s Guide to Transfiguration textbook when he met her in Flourish and Blotts and then dropped it back into her cauldron. (CS 4) Ginny later said she found what turned out to be Riddle’s Diary Horcrux in one of her textbooks, so Lucius had placed the diary inside Ginny’s Transfiguration textbook.

*This is a clear Transfiguration magic/Horcrux association.


8. The next mention of the trophy room is in CS7, when Ron is sent to polish the silver in the trophy room for detention: "Fourteen times he made me buff up that Quidditch Cup before he was satisfied. And then I had another slug attack all over a Special Award for Services to the School." (CS7)

*Although Ron’s assignment was to polish silver items, it’s apparent from the next passage that the Special Award for Service to the School is gold. This may be a flint or an indication that Ron had to polish Riddle’s award because he accidentally vomited slugs on the gold shield even though he hadn’t been assigned to polish it. 

9.  While walking past a classroom, Harry could hear Professor McGonagall, the Transfiguration teacher, shouting at a student who had turned his friend into a badger.  Later, Professor McGonagall appeared in the hallway with the student, who still had black-and-white-striped hair.  (CS11)

 *Helga Hufflepuff's animal emblem is a badger, so this passage clearly links Transfiguration magic with a badger, the same emblem that is on the gold Hufflepuff cup.

10. After Harry and Ron found the Riddle diary in Myrtle’s bathroom, Ron recalled that T. M. Riddle was the name of the student who got the Special Award for Services to the School that he had polished during detention. Harry, Ron, and Hermione returned to the trophy room to see if they could find more information about T. M. Riddle: "Riddle’s burnished gold shield was tucked away in a corner cabinet. It didn’t carry details of why it had been given to him [snip]. However, they did find Riddle’s name on an old Medal for Magical Merit, and on a list of old Head Boys." (CS13)

*This is the only mention of Riddle’s Medal for Magic Merit in all six books. Interestingly, it’s only mentioned once and only in a cluster of related objects. The heavy gold locket at 12 Grimmauld Place that many believe is the missing Slytherin locket Horcrux was similarly mentioned only once and only in a cluster of related objects.


11. A third mention of Riddle’s Award came when Harry began to write in the diary and Diarymort wrote back about the opening of the Chamber of Secrets 50 years earlier: "They gave me a nice, shiny engraved trophy for my trouble and warned me to keep my mouth shut." (CS13)

*The Award for Special Services to the School was given to Riddle for framing Hagrid as the culprit who opened the Chamber of Secrets, causing Moaning Myrtle’s death. It had taken Riddle five years to find the Chamber of Secrets, so it had galled Riddle to give Hagrid "credit" for being the Heir of Slytherin. The Diary Horcrux, in its capacity as a weapon, was Riddle’s means of insuring that one day he would receive credit for being the Heir of Slytherin who opened the Chamber of Secrets.


12. Diarymort told Harry that it had taken Tom Riddle five whole years to find the entrance to the Chamber of Secrets. (CS17)

*Since Riddle searched the castle for five whole years before locating the entrance to the Chamber of Secrets, he must have learned about one or more secret passages from Hogwarts to Hogsmeade. The Weasley twins found one of the passageways during their first week at Hogwarts.


13. Ron and Harry received Special Awards for Services to the School at the end of CS for their work in rescuing Ginny and destroying Diarymort (CS18), and those shields would have been placed in the trophy room with Riddle’s.

*This is a nice little twist since Harry received the same award as Tom Riddle for the same action: discovering the identity of the person who opened the Chamber 50 years earlier and killed Moaning Myrtle. More importantly, Harry’s actions revealed the true innocence of Hagrid and the true falseness of Tom Riddle in the Chamber episode, thereby switching the judgments of 50 years earlier.


14. The next mention of the trophy room is in Prisoner of Azkaban when the Weasley twins gave the Marauder’s Map to Harry in a third floor classroom near the statue of the one-eyed, humpbacked witch. Scanning the map, Harry noted that "Peeves the Poltergeist was currently bouncing around the trophy room." The map showed a series of passages leading from the school into various locations in Hogsmeade: "Right into Hogsmeade," said Fred, tracing one of them with his finger. "There are seven in all. Now Filch knows about these four"—he pointed them all out—"but we’re sure we’re the only ones who know about these. Don’t bother with the one behind the mirror on the fourth floor. We used it until last winter, but it’s caved in—completely blocked. And we don’t recon anyone’s ever used this one, because the Whomping Willow’s planted right over the entrance. But this one here, this one leads right into the cellar of Honeydukes. We’ve used it loads of times. And as you might’ve noticed, the entrance is right outside this room, through that one-eyed old crone’s hump." (PA10)

*This is the first of two references to Peeves bouncing around in the trophy room; this first one precedes a description of the school’s secret passageways.

*It should be noted that some secret passages are easier to find and open than others. The passageway behind the statue of Gregory the Smarmy that the twins found during their first week at Hogwarts is apparently easy to find and access. But Harry would not have known how to use the secret passageway through the one-eyed witch statue if the map hadn’t revealed the directions to him: "What did he have to do? He pulled out the map again and saw, to his astonishment, that a new ink figure had appeared upon it, labeled Harry Potter. This new figure was standing, about halfway down the third-floor corridor. Harry watched carefully. His little ink self appeared to be tapping the witch with his minute wand. Harry quickly took out his real wand and tapped the statue. Nothing happened. He looked back at the map. The tiniest speech bubble had appeared next to his figure. The word inside said, "Dissendium". (PA10) Moreover, after Snape caught Harry looking suspicious near the statue, Harry saw him "running one of his hands over the one-eyed witch’s head, examining it closely," trying to figure out what was special about it (PA14)

*Filch, as caretaker, should know about all secret passageways but apparently does not. Filch’s ignorance of the passageway near the one-eye, humpbacked witch near the trophy room is confirmed in PA when Harry noticed that although numerous security trolls had been hired to guard all entrances into the castle, the statue of the one-eyed, humpbacked witch was unguarded and unblocked (PA14). It’s an open question whether other members of the Hogwarts staff are aware of this passageway.

*The fourth floor passageway behind a mirror caved in during the winter of CS, but was clear during PS. It’s possible that Voldemort told Quirrell to use this secret passageway to sneak in the troll into Hogwarts on Halloween in PS. The text is unclear in pinpointing what floor the troll was on when it entered the girl’s bathroom where Hermione was crying, but the HP Lexicon has worked out that it was probably on the fourth floor. There was never any explanation given in PS to explain how Quirrell sneaked a 12-foot, rank-smelling mountain troll onto the fourth floor just before the Halloween Feast began (when teachers and students would have filled the corridors and stairways).

*Gunhilda of Gorsemoor (1556 - 1639), Famous Wizard Card #37
One-eyed, hump-backed witch who is known for developing a cure for Dragon Pox. 
This is not in the books, but it’s possibly a clue since Rowling writes all the copy for the Famous Wizard cards. There can’t be too many one-eyed, humpbacked witches commemorated with a statue at Hogwarts or Famous Wizard card, so it’s a good guess that the statue leading to the secret passage to Honeydukes is Grunhilda of Gorsemoor. She was born around 500 years after Slytherin left the school, so Tom Riddle might not have found the secret passageway to Honeydukes in his search for the opening of the Chamber of Secrets if he concentrated on areas old enough to be around before Slytherin left the school and/or if he only recited various incantations in Parseltongue, knowing that only the Heir of Slytherin could open the Chamber of Secrets and expecting that his ability to speak Parseltongue would be the key to opening it. Also, the password through Gunhilda is "Dissendium," not a word that would immediately come to mind to open a passageway through a statue up on the castle’s third floor. I’m taking these clues as hints that Voldemort is unaware of the secret passageway through the one-eyed, humpbacked witch even if he knows of other secret passageways.


15. The next time the trophy room is mentioned is in Goblet of Fire when Harry, fresh from his after-curfew bath with the Golden Egg in the prefects’ bathroom, checked the Marauder’s Map, once again saw Peeves bouncing around in the trophy room, and also saw Bartemius Crouch in Snape’s office. (GF25) Determined to follow Crouch, Harry ran down the stairs in his invisibility cloak and became trapped when his leg fell through a trick step. The map went flying and the egg bounced down the stairs, then opened up and let out a screeching noise. Following the noise, Filch appeared shortly followed by Snape; both in their nightshirts. Snape mentioned that on the way he noticed his office door open, torches lit inside, and a cupboard door open; he then mentioned he was missing potions ingredients and hinted that students attempting illicit mixtures were guilty (that should have reminded us that Hermione stole from Snape’s private cupboard to make Polyjuice in CS). Fake Moody appeared next, saw Harry under the Invisibility Cloak with his magical eye, took the map before Snape could get it, and got rid of Filch and Snape. Harry mentioned seeing Barty Crouch on the map in Snape’s office; Fake Moody scanned the map at this, and, "He looked suddenly alarmed." Moody claimed not to see Barty Crouch on the map even though Harry had seen him only minutes before, and Crouch couldn’t have gotten far enough away to fall off the map. Fake Moody asked Harry if he could borrow the map, and then sent Harry off to bed.

*This is the second of two references to Peeves bouncing around in the trophy room; this second one preceded a series of clues showing the reader that Professor Moody is not who he appears to be. As we all know, Fake Moody was Death Eater Barty Crouch, Jr. transformed to appear as Order of the Phoenix member Alastor Moody (another good-evil inversion). So once again, a mention of the trophy room was closely linked to a transformation in which one thing (Crouch) was magically altered to appear as another thing (Moody).


16. In Order of the Phoenix, Peeves is linked to Transfiguration. When Harry wanted to used Umbridge’s fireplace to check on Sirius, Hermione suggested diverting Umbridge by telling her that Peeves was up to something: "I'll do it," said Ron at once. "I'll tell her Peeves is smashing up the Transfiguration department or something, it's miles from her office. Come to think of it, I could probably persuade Peeves to do it if I met him on the way." (OP32)

*Peeves has been linked to the trophy room in a passage introducing the secret passageways, in a passage introducing key clues that reveal Fake Moody as a transformed importer, and here he is linked to the Transfiguration classroom (associated with switching, inversions, false identities, physical transformations).


17. In Half-blood Prince we learned about Horcruxes, Voldemort’s collection of distinguished "trophies" used to house parts of his soul. We saw the Hufflepuff cup in HBP20 in the pensieve memory of Riddle’s visit to Hepzibah Smith: it was a small gold cup engraved with a badger with two finely wrought handles.

*Transfiguration magic in its many versions is frequently described in the six Harry Potter books to date. A small gold cup could easily be Transfigured to look like any number of objects; however, when we see the Transfiguration of objects, the starting and ending objects often have associations of various types such as similarity of phonics (beetles into buttons), of name (guinea fowl into guinea pigs), of shape (matchsticks into needles), of size (mice into snuffboxes), of a key physical attribute (hedgehogs into pincushions), etc., but sometimes the objects have no apparent connection other than size (desk into pig, rock into terrier, man’s corpse into a bone). The small gold cup could easily be Transfigured into a number of small gold objects of any appearance.


18. In HBP20, Dumbledore recounted to Harry that Voldemort had gone to work for Borgin and Burkes after leaving Hogwarts: :He reached the seventh year of his schooling with, as you might have expected, top grades in every examination he had taken. All around him, his classmates were deciding which jobs they were to pursue once they had left Hogwarts. Nearly everybody expected spectacular things from Tom Riddle, prefect, Head Boy, winner of the Award for Special Services to the School."

*What is curious about this passage is that Dumbledore did not mention the Medal for Magical Merit that we saw in the trophy room in CS. While it could be that the Medal for Magical Merit was given to Riddle for his top examination grades, no such award has been mentioned in connection with Bill or Percy Weasley, each of whom had earned twelve OWLS (the most you can receive) and had been prefect and Head Boy. We certainly would have heard about a Medal for Magical Merit if Percy had received it, so it appears not to be a commonly awarded honor. And logic tells us it's not a common award since we do know that becoming Head Boy is an exceptional honor, yet Head Boys are only remembered by their names on a list, not by individual objects like badges or medals.  So if it’s not a commonly-awarded honor, then all the more reason for Dumbledore to have remembered Tom Riddle’s receiving it. But Dumbledore didn’t mention this apparently rarely-awarded medal, so we have to consider that it wasn’t awarded to Tom Riddle at all, but rather created by him and Dumbledore was unaware of its existence.

19. We’ve learned over the course of the books that Dumbledore never really trusted Riddle and that Riddle never tried to charm Dumbledore as he had the other teachers. We learned in HBP that the admissions of unethical magic made by Riddle to Dumbledore in the orphanage were the original source of this mutual distrust and that Slughorn had advised Riddle not to mention Horcruxes to Dumbledore because he was particularly fierce about the subject and had maintained (if not imposed) a school-wide ban on the subject.

*Voldemort, I suspect, would take keen pleasure in planting a Transfigured Horcrux under Dumbledore’s nose at Hogwarts since 1) Riddle regretted giving Dumbledore information revealing his ability to speak Parseltongue and his predilection for cruelty, secrecy, and control and probably resented Dumbledore’s knowing so much about him, 2) Dumbledore was even more distrustful of Riddle after Moaning Myrtle’s death and kept an annoyingly close eye on Riddle after Hagrid was expelled, 3) Dumbledore was particularly fierce on the subject of Horcruxes whereas Riddle was particularly keen on it, and 4) Dumbledore was the Transfiguration master who had taught the subject to Riddle in the first place.


20. Dumbledore made various unsuccessful attempts to bypass the poison in the sea cave. He told Harry, "This potion cannot be penetrated by hand, Vanished, parted, scooped up, or siphoned away, nor can it be Transfigured, Charmed, or otherwise made to change its nature." (HBP26)

*Although Dumbledore was unsuccessful in transforming the poison, it’s key that he mentioned trying to Transfigure it into something else or otherwise to make it change its nature. It’s also important to note that he was working with a protection covering a Horcrux, not the Horcrux itself.


It’s easy to see the breadcrumb trail of interweaving and overlapping references to Transfiguration magic, secret passages/Marauder’s Map, and the trophy room running through the Harry Potter books. In the context of Book 7’s hunt for the remaining Horcruxes, this trail of set-ups is arguably pointing to a Transfigured Horcrux in the trophy room at Hogwarts.

Many of us suspect the Slytherin Locket Horcrux is the heavy gold locket that nobody could open at 12 Grimmauld Place. The only other known Horcrux object likely to be hidden in the Hogwarts trophy room is the Hufflepuff cup. And the cup, seeming to be a tiny loving cup, fits an associational pattern seen throughout the books in Transfiguration magic, so it’s the best fit for a Transfigured Horcrux hidden in the trophy room. The association between the names Emeric Switch and Helga Hufflepuff (both with connotations to work, Switch pointing to Transfiguration), are clues.  The accidental Transfiguration of a student into a badger (Hufflepuff's mascot) also point to Hufflepuff's Cup being the object in question.

The object we’ve seen most likely to be the Transfigured cup is Tom Riddle’s Medal for Magical Merit. I had at first questioned it because Voldemort hates his Muggle name, but if for no other reason than plot practicality, the trio need to be able to identify it as belonging to Riddle/Voldemort, and since Tom Riddle’s name is on the Award for Special Services and the Head Boy list, the name would raise no suspicions to anyone looking around the trophy room. However, I won’t be surprised if the medal is examined closely and found to have a tiny badger on it similar to the tiny snake on the bathroom tap marking the opening to the Chamber of Secrets. Moreover, the fact that his name is on the Horcruxed Medal fits a pattern whereby Voldemort leaves evidence in Horcrux locations of what he has done.  See the essay explaining the green potion in the cave:

Why would Voldemort hide a Horcrux in the trophy room at Hogwarts? Horcruxes are trophies as we learned in HBP, and the trophy room, a room never locked that no one ever goes into, would not be suspected as a place where Voldemort had hidden part of his soul. Hogwarts is the most well-protected building in Britain, and Lord Voldemort had happy memories there as student Tom Riddle. And for practical purposes, Harry and the trio need to find at least some of the remaining Horcruxes that are relatively unprotected (relative to the powerfully cursed Peverell ring and locket). There would be no need to protect a Transfigured Horcrux that looked like hundreds of other objects in a little-used room, and since the trophies in the room are occasionally handled for polishing, the Horcrux couldn’t be cursed in the manner of the opal necklace or Peverell ring.

Lastly, I agree with others that a confrontation between Harry and Voldemort will happen at Hogwarts. It’s the place both love best in the world and is a place Voldemort would very much want to control, especially if he has a Horcrux or two hidden there. With Dumbledore gone, the way is open to him. Hogwarts will need to be the setting for a showdown for reasons related to plot practicality; in the battle at the Ministry of Magic at the end of OP, Dumbledore was able to Apparate into the atrium in time to save Harry from Voldemort’s curse, Dumbledore was able to Disapparate before Voldemort’s Avada Kedavra curse reached him, and Voldemort was able to Disappate out of the building when he sensed a lost cause. So Harry and Voldemort will need to face off in a place in which Apparation and Disapparation are not possible, and the two places we've seen that fit the bill are Hogwarts and the Department of Mysteries (where I think the final battle will take place because of the Veil in the Death Room and the Love Room containing the most powerful magic known in the Potterverse).

I believe the reason why clues linking Transfiguration magic and trophies are interwoven with references to the Marauder’s Map and secret passageways running from Hogwarts to Hogsmeade is that Harry will need to get into and out of the castle without Voldemort's knowledge, and he won't be able to use Apparation or conventional entrances. Not only does the map show us how Tom Riddle could have slipped the Transfigured Horcrux into Hogwarts without being noticed, but it hints that Voldemort probably does not know about all the secret passageways. If he knew about the fourth floor passageway through the mirror and used it to help Quirrell get the troll into the school in PS, then he’ll find out it’s now blocked. He probably does not know about the passageway from the one-eyed, humpbacked witch to Honeydukes for the reasons argued above, and that passageway leads to the third floor, down the hall from the trophy room.

One last thought about the passageways. Who knows about them among the people who will be at Hogwarts in Book 7, and how many do they know about? Harry, Ron, and Hermione (and anyone they share the map with) will also know about all the secret passageways. The twins know about them all because they had memorized the map before handing it to Harry. The biggest potential surprise could come from the two remaining Marauders: Peter (Wormtail) Pettigrew and Remus Lupin since both created the Marauder’s Map, so both know about all the secret passageways. Will this be connected to the way Wormtail repays his life debt to Harry?  I have a hunch it will.