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. http://en.wikipedia.org/wiki/Naga_%28mythology%29
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." (OP22).
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 (http://swordofgryffindor.com/), 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. (http://felicitys-mind.livejournal.com/2342.html) 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.