The imminent demise of the Dark Lord gives us tremendous potential for speculation. How will Harry do it? Will Harry do it? Will someone else do it for him? Will it happen at all?
I believe that it certainly will happen. JKR didn't bring Harry through six books to have him fail at his quest. Voldemort must be rooted out. The question is, how? We know part of it: Harry & Co. have to find and destroy all of the Horcruxes (how they can be certain they have found them all is beyond me - I guess it is back to trusting Dumbledore's judgment, isn't it?). Then, they have to find Voldemort (unless he finds them first). Finally, someone, presumably Harry, has to kill (or vanquish) him. The means by which this will happen is a great mystery. Will Snape help and thereby prove his loyalty? Will Wormtail's Life Debt be paid in the final moments? Possibly, but not necessarily. We don't know when those particular plot bits will be tied up.
I feel fairly certain that when Snape yelled, "No unforgivables for you, Potter," it was a clue. I don't think it was only a warning to Harry to learn Occlumency, or even nonverbal spells, though that is part of it. I think that Snape knows that Harry cannot destroy Voldemort with Avada Kedavra.
First, and very important: Harry and Voldemort cannot duel effectively with their current wands. The wands will not fight each other because they share the same core: a feather from Fawkes, the Phoenix. Besides, having Harry fire off an AK would be fighting Dark with Dark. It just sounds wrong to me. As I have said before, Dark doesn't defeat Dark. Light defeats Dark. I believe there must be a way that Harry will fight Dark with Light. The Prophecy says that "the One" (Harry) has a "power the Dark Lord knows not." We know that this power is Love. If this is Harry's special gift, is there some way that the Light of Love will ultimately defeat Voldemort?
Random Facts of Potter
It makes sense that Love will be the ultimate "weapon" of choice, since it is the "power the Dark Lord knows not." But the image of Harry somehow "loving" Voldemort to death does seem a bit absurd, even though it's good for a laugh. However, there may be another way. Let's look at some seemingly random facts:
1. Harry's worst fear, up to this point, has been Dementors.
2. Dementors feed on good thoughts and memories until a person has nothing left but his worst experiences.
3. A large crowd is a feast for Dementors.
4. When they get the chance, Dementors suck out the soul and leave their victim the barest of vacant human shells.
5. Despite his fear, Harry is very gifted at conjuring a Patronus and protecting himself and others from Dementors.
6. A Patronus is a spell of Light - bright, hopeful, loving Light.
7. Light defeats Dark.
8. Harry has used his powerful Patronus to fight multiple Dementors twice before: two Dementors on Privet Drive, and at least a hundred Dementors by the lake at the end of PoA.
9. A Patronus is conjured by summoning the happiest of memories.
10. Though Lupin specifies memory as the key to a successful Patronus, Harry also conjures them by focusing intently on a deep wish and even by acting decisively and confidently, with no apparent thought.
11. When Harry learned to conjure the Patronus, Lupin told him that the happiness he felt from the first time he flew wasn't good enough. He needed a stronger connection. When Harry remembered how he had felt when he heard he was a wizard, he was able to conjure the beginnings of a Patronus, but not a "Corporeal Patronus," as the late Madam Bones would say.
12. Harry's Patronus has been conjured over the course of the series by using the following images:
a. Becoming a wizard - partial Patronus in first lesson, PoA
b. Without thinking at all - Corporeal Patronus, at the Quidditch match, PoA
c. Living with Sirius and escaping the Dursleys - "a wisp" of a Patronus, at the lake, PoA
d. Instinct/self knowledge (he knew he could do it because he "had done it before") - Corporeal Patronus, at the lake, PoA
e. His love for Ron and Hermione - Corporeal Patronus, on Privet Drive, OotP
f. Umbridge getting sacked - Corporeal Patronus, during OWLS, OotP
13. The Dementors are breeding. Baby Dementors are on the way.
14. Babies are always hungry.
15. Voldemort does not know Love and has never known Love.
16. Voldemort's immortality depends entirely on the safety and survival of his scattered soul. (Granted, there may be other protections on Voldemort besides the Horcruxes, but not that we know of yet.)
Question: could Voldemort conjure a Patronus, given his angry, embittered state? Certainly, Voldemort is a hugely powerful wizard. And he would have his own brand of "happy thoughts," I suppose (Harry's head on a platter...). But if ever a spell constituted "Light" Magic (as opposed to Dark Magic) it is the Patronus Charm. It is Light, in every sense of the word - it is positive, protective, and it is made of the substance of Light itself. It is true that Harry managed to successfully cast it by imagining Umbridge sacked, which wasn't exactly a "noble" happy thought. So, perhaps Voldemort could do it too. But it seems contrary to everything we know about Voldemort. Maniacal laughter is the closest thing to real joy that we have heard from the Dark Lord. What on earth would Voldemort's Patronus be? A Basilisk? Might it be that Voldemort has so immersed himself in Dark Magic for so long that he is as incapable of casting a Light charm as Harry is of casting a Dark curse? The only Dark curse that Harry has cast successfully is Sectumsempra, which he used on Malfoy, and he didn't know what he was doing at the time. Harry has been a washout on the Unforgivables. He's tried Crucio a couple of times and either isn't quick enough or cannot sustain the curse. Could Voldemort be just as limited regarding Light magic?
Is there a quality or level of happiness that is essential to creating a powerful Patronus? If the memory of Harry's first flight was not enough, then it seems that it requires something of a finer quality. Even his thoughts of Umbridge being sacked at least carried the hope of saving Hogwarts and everyone in it from Ministry insanity.
The rush of need also worked for Harry during the Quidditch match. In that case though, we must remember, he was not facing real Dementors, but Malfoy & Co. in costume. However, Harry also succeeded by instinct, clarity and confidence at the lake in PoA, on Privet Drive and during OWL's. Harry has always been at his best in a crisis that requires instinct. Something in him tends to know the right thing to do in a desperate moment, and he finds the power to do it.
Voldemort probably has keen instincts as well, and he does not lack confidence. In fact his confidence extends to the point of hubris, more often than not. However, if connection to Light and one's own heart is essential to the execution of a successful Patronus charm, I think Voldemort might be in trouble. Is there enough real joy in Voldemort to conjure a Patronus? Are sadistic thoughts of domination, power, control and murder enough to conjure a Patron Saint? A Guardian Angel? A Holy Spirit? For, surely, that is what the Patronus represents.
We know that everyone in the Order can conjure one, as they use their Patronuses for secret communications. Ron, Hermione, Cho, and several other DA members can also conjure them. Harry taught them. And, as far as I recall, though the DA's Patronus Charm lesson took up some significant space in OotP, they have never yet had reason to use them. It's interesting that this protective and positive charm is one thing that so many of Harry's friends learned and/or used while participating in groups called Dumbledore's Army and the Order of the Phoenix. Dumbledore: the ultimate Light Wizard.
Harry's Patronus seems to be rather special. Remember, at age thirteen, he conjured a Patronus so powerful that it chased away a hundred Dementors at once when they were about to feast on his and Sirius' souls. And Harry was only thirteen. By the end of Book Seven Harry will be seventeen - almost eighteen - and he will have seen and done a great deal since Lupin guided him through the confrontation with the Dementor-Boggart. He has also developed a great deal more control over himself and his magic.
The Dementors have now left Azkaban. They are no longer "under Ministry control" (were they ever?). Are they under Voldemort's control? If so, do they have any more capacity for loyalty than the Dark Lord himself? What will happen when all of the Dementor newborns begin to grow and get hungry? Will they seek out crowds to feast on? Will Voldemort or anyone else be able to exert any control over them whatsoever?
The Dark Lord Demented
Imagine if you will that we have come to the final chapters of Book Seven. Harry has found and destroyed all of the Horcruxes that Voldemort filled with soul bits and scattered around the planet. We have heard about the Dementors, on the periphery of the story. They are out there, looking for food and attacking individuals when they get the chance. But they haven't figured into the picture yet, since the soul bits in the Horcruxes are so well protected.
Harry has called upon his own reserves of power and knowledge and has been the recipient of a great deal of help from his greatest resource: his friends. His confidence and determination are at an all-time high, and he has the happiest of motivations to guide him: Love. He is in love with Ginny, he has found love and family in Ron, Hermione and the Weasleys, he has friends and colleagues among the Order and at Hogwarts, and he wants to survive, to root out this evil and make a safe place for all of those he loves. His greatest obstacle will be fear of failure, and fear of losing someone else he loves.
I believe that Harry will transcend his need for revenge killing before he finally meets Voldemort again. This may involve a transformation of his relationship with either Draco or Snape. He will see the emptiness and futility of revenge as a motivator. He will go after Voldemort with a much more powerful motivation: to save those he loves and create a peaceful future for them.
Voldemort will not be alone. He will be certain to have supporters around him. He will demand it of his Death Eaters because he fears, and they will acquiesce to his demands, because they fear. It is said that the opposite of Love is not Hate. It is Fear. Where Fear is present, there cannot be real Love and where real Love prevails, Fear is defeated. Voldemort is terrified of Death, or else he would not have spent his entire life trying to escape it. Even his name means "fly from death." (It can also mean "to steal death - or theft of death." The verb voler in French means both "to fly" and "to steal.") I think that Fear is the primary motivator for Voldemort and for all of his followers.
Though Harry may be leading the charge for the opposing team, I do not believe he will be alone either. Too many people have too much at stake to sit home and let Harry do their dirty work. While many in the wizarding world will hide at home and hope for the best, the fine folk that we have met over the series will be there to help, as they have been all along; because they love. And Harry will dive into the fray, because he loves. Love is the primary motivator for Harry and his friends. Within Harry's circle of friends, I include Dobby, Witherwings, Fawkes, Firenze, and other creatures that have found acceptance and friendship in Harry's open, loving nature.
Who else might be attracted to this crowd of people who have come together and are exuding such strong emotions, thoughts and memories? I surmise the Dementors and their hungry young will find the spot as well. Voldemort probably doesn't fear them as much as Harry does, because he hasn't had happy thoughts for them to steal, and because, somehow, he has been able to exert control over them - up until now.
But this rush of human emotion and excitement draws hundreds, perhaps thousands, of Dementors to the final confrontation. Patronus charms are cast, and the Order holds them off for a time. But they are hungry, and they go after whatever they can get.
Harry is now facing not only his worst enemy, but also his worst fear. The Dementors have a powerful effect on Harry. The fact that he has become so proficient at defeating them is a testament to his Gryffindor courage and mettle as well as his power of Love. The strength of Harry's Patronus is probably in direct proportion to the quality of thought, wish or memory that conjures it. Because they bring out his greatest strengths and his greatest fears, it makes sense to me that Harry is not going to complete his quest without another challenge from the Dementors. They have provided too profound an obstacle for him in the past.
Harry knows what to do. He imagines a world free from Voldemort. He imagines making his own home and family with Ginny, and spending many happy years with the Weasleys, Hermione and whoever else has survived by this point in the story. He remembers the courage of his parents, of Sirius and of Dumbledore. He conjures a Patronus -a very impressive Patronus!
Will it still be a stag, or has it changed, as Tonks' did? Lupin tells Harry that a Patronus can change due to "a great shock... an emotional upheaval." Harry has certainly experienced both by the end of HBP. Could his Patronus reflect his life experiences and loyalties? Could it now be, perhaps, a Phoenix? Might this glorious Phoenix Patronus circle above Harry and all of his friends, leading their Patronuses (Patroni? Patronae?) and keeping everyone safe from attack?
When Dumbledore is explaining to Harry the importance of his power to Love, he reiterates that Voldemort underestimates this power, and does not value it. He reminds Harry time and again that this is what makes him different than Voldemort.
If Love is the power that can defeat the Dark Lord, Harry may not have to actually cast a spell on Voldemort, thus resolving the problem of shared wand cores. He may be "The One" simply because he inspires others to love as he does, and this inspiration will finally unite the Wizardkind in an army of Light - Dumbledore's Army, led by Dumbledore's symbol: a Phoenix. Harry may be "The One" because his heart, which saved him from Voldemort's attack in OotP, has a greater capacity than others' - it has withstood more assaults, and grown strong from the struggle. It may help to create the ultimate Patronus - a Patronus that no Dementor could penetrate. If so, the hungry creatures will turn quickly to the unprotected.
Will any of the Death Eaters have a decent Patronus to offer the Dark Lord? With his empty heart and ripped and crippled soul, will Voldemort find the joy and optimism in himself to successfully conjure one? Or will he be the easiest of prey to the Dementor's Kiss? Will another Phoenix, Fawkes himself, appear with his haunting song to bolster the pure of heart and weaken the Dark forces even further?
Dementors make us relive our worst memories. What could Voldemort's worst memories be? He has many, I'm sure. He was a desperately unhappy child, loveless and alone. He was an angry youth, with destruction and domination already on his mind. But his worst memories probably all involve the same subject: Harry. Can you imagine the memory of his own Avada Kedavra shooting straight back at him in Godric's Hollow? Of seeing Harry push that bead of light slowly back towards Voldemort's wand in the graveyard? Or, the memory of his own victims, conjured from his own wand to help his nemesis? Remember the Dark Lord's furious cry when Harry touched that Triwizard Cup and escaped back to Hogwarts with Cedric's body? How about the memory of agony in the Ministry when he tried to possess Harry? Or, the feelings of utter frustration and defeat when he learned that the Prophecy had been smashed? How did he feel when he found out that Lucius had carelessly let the Diary out of his hands, and that both it and the Basilisk had been destroyed - by Harry?
Will anyone come to Voldemort's rescue and stop the Dementors from rendering him helpless? I can imagine DE's dropping like flies from the horrors of the Dementors, until the Dark Lord himself is attacked and ultimately kissed, his last bit of soul sucked from his mangled body as Harry instructs the Patronus army to chase away the Dementors once and for all.
It would warm my heart if Harry's ultimate triumph resulted from the Charm that Remus Lupin taught him. It makes sense, if a large heart is a prerequisite to a successful Patronus, that Lupin is so skilled at conjuring one. Like Harry, Lupin has had many challenges in his life that would have made a lesser man close his heart. And, though Lupin needs some coaxing to accept Love for himself, he has never ceased to give it openly and willingly.
JKR has said that the film of PoA included foreshadowing of things that would become important in later books. There are many things that this could refer to. However, I note that Lupin's Patronus lesson is slightly different in the film. In the book, Harry conjures his first semi-Patronus from remembering what he felt when he learned he was a wizard. In the film, the Patronus is conjured when Harry remembers his parents talking to him. He feels the love of family, and not with a sense of sadness or grief. It brings him confidence and happiness. Could this be leading to the thoughts, memories and wishes that will ultimately serve Harry in his final confrontation with Voldemort?
It would be a fitting contribution for Lupin, who is struggling to bear his seemingly fruitless efforts with the werewolves. Though Lupin stayed patiently focused on task with his customary stoicism, I was getting worried about him in HBP. How much can the poor man bear? Will something happen to make Lupin feel that his contribution has been useful and worthwhile? As the last connection to James, Lily and Sirius, I hope that Lupin is somewhere close by to see his work with Harry spring forth in a blaze of Patronus Light.
After the Battle
In OotP, Dumbledore tells Voldemort that there are other ways of destroying a man, besides killing, and that merely taking Voldemort's life would not satisfy him. His words could be interpreted several ways, and certainly have to do with the fact that Dumbledore knew the Dark Lord had made Horcruxes. But it's also probable that, for some reason known only to him, Dumbledore sees a different fate in store for the Dark Lord than a simple death.
If all of Voldemort's Horcruxes were destroyed before a Dementor attack, it seems that what is left of his soul would be sucked out and Tom Riddle would be left to waste away and eventually die, just like any other human being - helpless and harmless. Remember, Lupin told us that the Dementor's Kiss leaves its victim worse than dead. He says, "You'll have no sense of yourself anymore, no memory, no... anything. There's no chance at all of recovery. You'll just... exist. As an empty shell."
If all of Voldemort's Horcruxes were not destroyed, could it be that the shell known as Tom Riddle would live forever, stuck in a soulless body for all eternity? His ricocheted AK seemed to destroy Voldemort's first body, but leave his bit of soul intact to exist as Vapormort, until he was able to create a new body. Would a Dementor attack do the opposite? Would it destroy his soul while leaving his body intact? If a hidden Horcrux would save his body from death, Voldemort would have his wish - he would be "immortal." But what a heinous immortality to contemplate! Perhaps this is the fate of Voldemort. He will live forever, as he always wished, but with no awareness of himself, no power, no friends, and no hope - the epitome of Hell.
Of course, should the second option come to pass, it would be a precarious peace. There would still be a soul fragment in a Horcrux, somewhere out there. If anyone managed to get that Horcrux and reunite the soul fragment within it with the body of Tom Riddle, would the Dark Lord rise yet again?
Perhaps Harry's fate is to remember, always, that the potential for evil still exists, somewhere, and that the right (or wrong) circumstances and actions could always reignite its power. Perhaps Harry's fate is to learn that, while it is possible to triumph over evil, and to live on to create a life we have only dreamt of, the Darkness will always attempt to put out the Light. Perhaps it will be his final task to be Dumbledore for the next Harry.
Perhaps the qualities of the Hogwarts houses - knowledge, wisdom, courage, hard work, loyalty, ambition and shrewdness must be gathered, cultivated and honed in each of us if we are to become the masters of our own lives and souls and keep our Darkness in check.