And yet one more theory!
I've got a theory about the prophecy, regarding the "neither can live while the other survives" part. It's obviously very spoilery, so I'll post it behind the cut.
maeglinyedi posted a theory about Snape being the one to eventually kill Voldemort - his body and perhaps the last fragment of his soul with it.
It got me thinking that the prophecy doesn't actually SAY that Harry must murder Voldemort, but we all jumped to that conclusion - including Harry because it implied that he must by saying that either must die at the hand of the other. The horcruxes change that.
Now, you'll have to bear with me. This gets long.
Dumbledore made a big show of not having Draco personally kill - it makes sense that he wouldn't want Harry's soul to suffer from committing murder either. So I think maeglinyedi has an excellent point with regard to Snape.
Now, the thing about the horcruxes - they are sort of 'entombed' or embedded within the objects - the ring, the diary, the locket, the cup, the snake. When the killing curse went wrong with Harry, we don't know if the part of Voldemort's soul that was inside his body was destroyed, therefore leaving the part he was trying to embed in an object to roam free, formless - or, if the part of his soul that was released from his body was the one that fled. The killing curse is unblockable. If the spell "rebounded", Voldemort should have been dead - and his body was killed. But it could not destroy his soul because his soul was already fractured. So his body died, and perhaps one of the bits of his soul, but he was still 'alive' because all of the pieces of his soul were not destroyed.
If he was trying to embed a part of his soul that night, it's not impossible to believe that that part of his soul was accidentally 'implanted' in Harry. His scar. The killing curse itself does not mark its victims. Yet Harry was left with a scar, and a very unusual one at that.
I think the fact that Voldemort was able to see through Nagini's eyes in the Ministry the night he attacked Arthur is very important. And I also think that it's a clue that Harry may indeed be an accidental horcrux. The other objects he used as horcruxes are inanimate objects with no consciousness. Nagini (and Harry) however, are living receptacles. He can't tell when a non-living horcrux is destroyed because there is no consciousness connecting him to that fragment of his soul.
When Harry dreams that night, it's from the perspective of Nagini. Why is he able to see from Nagini's perspective? Dumbledore tells him it was because Lord Voldemort was also inside the Snake at the time, but he doesn't elaborate. When Harry reveals his perspective to Dumbledore, Dumbledore is intrigued, and (after taking measures to rescue Arthur) goes to one of his silver instruments in his office, plays around with it - a smoky snake appears and says "Naturally, naturally. But in essence divided?" Harry can speak parseltongue because Voldemort can speak parseltongue...
I thought at first that this was when Dumbledore realized exactly what Voldemort must have done and put it all together, but he was given a clue in Harry's second year with the Diary. So I'm thinking now that this was just another clue as to where the remaining horcruxes might be, and a hint that perhaps Nagini and Harry are connected.
He had already investigated Tom Riddle's past looking for clues about how to destroy him 20 years ago during his first rise, but the horcrux information (confirmation perhaps?) was fairly new. And when Dumbledore leaves (is forced out of) the school, he sets off on his 'quest' to find the rest of the horcruxes - part of why he says he's not going to be staying at Order Headquarters.
Voldemort must have a way of removing his soul fragment from the horcrux if needed. Likely it would require destroying the object. But to get it out of a living receptacle would probably kill the receptacle. Remember - his free roaming soul was able to "possess" others, but they died rather quickly - And Quirrel died when Voldemort fled from his body.
So, Harry, possessing the last bit of his soul, would have to die for Voldemort to live. If the other fragments of Voldemort's soul are destroyed, along with his body, the part of his soul in Harry cannot escape because there would be no one to release it. So in essence, Voldemort cannot live while Harry survives. And Harry cannot "live" while the rest of Voldemort survives, because Voldemort would have the connection with Harry through the soul fragment and would take any measures possible to 'release' and retrieve it. There's a difference between living and merely existing. And she did say the prophecy was phrased very specifically.
I'm not sure where "love" plays into all of this, but perhaps it is a kind of shield for Harry that protects him - his own soul - from the fragment of Voldemort's soul within him.
Anyway, it's just a theory. Or part of one at any rate. But a fun one at that. :)
ETA: Thanks to cs_whitewolf and lauren_b for pointing out the passage in CoS:
In CoS, at the end:
"You can speak Parsletongue... because Lord Voldemort... can speak Parseltongue. Unless I'm much mistaken, he transferred some of his own powers to you th enight 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."
And the more I think on it, I believe Voldemort is not able to share Harry's body because of the "power the dark lord knows not" - Love. Harry's love - and Lily's love - act like a shield for him. At first it was also a physical shield - Voldemort couldn't touch him. But by using Harry's blood to resurrect himself, he overcame that particular protection. Dumbledore certainly hinted that there were more, and we can't forget that gleam in his eye when Harry told him that Voldemort had taken his blood at the end of GoF.
As for another theory - I also think that Voldemort had the idea of using Hogwarts itself as a horcrux. It's certainly a very powerful magical object, infused with the magic of the four founders, and, it's very possibly sentient. If my theory about living and non-living horcruxes is anywhere near correct, just think how powerful he would be if he was able to tap into the power of Hogwarts itself! I think that is one of the main reasons why he was so eager to obtain a teaching position there. Only a theory, like my previous one above, but a cool one to think about :)
maeglinyedi posted a theory about Snape being the one to eventually kill Voldemort - his body and perhaps the last fragment of his soul with it.
It got me thinking that the prophecy doesn't actually SAY that Harry must murder Voldemort, but we all jumped to that conclusion - including Harry because it implied that he must by saying that either must die at the hand of the other. The horcruxes change that.
Now, you'll have to bear with me. This gets long.
Dumbledore made a big show of not having Draco personally kill - it makes sense that he wouldn't want Harry's soul to suffer from committing murder either. So I think maeglinyedi has an excellent point with regard to Snape.
Now, the thing about the horcruxes - they are sort of 'entombed' or embedded within the objects - the ring, the diary, the locket, the cup, the snake. When the killing curse went wrong with Harry, we don't know if the part of Voldemort's soul that was inside his body was destroyed, therefore leaving the part he was trying to embed in an object to roam free, formless - or, if the part of his soul that was released from his body was the one that fled. The killing curse is unblockable. If the spell "rebounded", Voldemort should have been dead - and his body was killed. But it could not destroy his soul because his soul was already fractured. So his body died, and perhaps one of the bits of his soul, but he was still 'alive' because all of the pieces of his soul were not destroyed.
If he was trying to embed a part of his soul that night, it's not impossible to believe that that part of his soul was accidentally 'implanted' in Harry. His scar. The killing curse itself does not mark its victims. Yet Harry was left with a scar, and a very unusual one at that.
I think the fact that Voldemort was able to see through Nagini's eyes in the Ministry the night he attacked Arthur is very important. And I also think that it's a clue that Harry may indeed be an accidental horcrux. The other objects he used as horcruxes are inanimate objects with no consciousness. Nagini (and Harry) however, are living receptacles. He can't tell when a non-living horcrux is destroyed because there is no consciousness connecting him to that fragment of his soul.
When Harry dreams that night, it's from the perspective of Nagini. Why is he able to see from Nagini's perspective? Dumbledore tells him it was because Lord Voldemort was also inside the Snake at the time, but he doesn't elaborate. When Harry reveals his perspective to Dumbledore, Dumbledore is intrigued, and (after taking measures to rescue Arthur) goes to one of his silver instruments in his office, plays around with it - a smoky snake appears and says "Naturally, naturally. But in essence divided?" Harry can speak parseltongue because Voldemort can speak parseltongue...
I thought at first that this was when Dumbledore realized exactly what Voldemort must have done and put it all together, but he was given a clue in Harry's second year with the Diary. So I'm thinking now that this was just another clue as to where the remaining horcruxes might be, and a hint that perhaps Nagini and Harry are connected.
He had already investigated Tom Riddle's past looking for clues about how to destroy him 20 years ago during his first rise, but the horcrux information (confirmation perhaps?) was fairly new. And when Dumbledore leaves (is forced out of) the school, he sets off on his 'quest' to find the rest of the horcruxes - part of why he says he's not going to be staying at Order Headquarters.
Voldemort must have a way of removing his soul fragment from the horcrux if needed. Likely it would require destroying the object. But to get it out of a living receptacle would probably kill the receptacle. Remember - his free roaming soul was able to "possess" others, but they died rather quickly - And Quirrel died when Voldemort fled from his body.
So, Harry, possessing the last bit of his soul, would have to die for Voldemort to live. If the other fragments of Voldemort's soul are destroyed, along with his body, the part of his soul in Harry cannot escape because there would be no one to release it. So in essence, Voldemort cannot live while Harry survives. And Harry cannot "live" while the rest of Voldemort survives, because Voldemort would have the connection with Harry through the soul fragment and would take any measures possible to 'release' and retrieve it. There's a difference between living and merely existing. And she did say the prophecy was phrased very specifically.
I'm not sure where "love" plays into all of this, but perhaps it is a kind of shield for Harry that protects him - his own soul - from the fragment of Voldemort's soul within him.
Anyway, it's just a theory. Or part of one at any rate. But a fun one at that. :)
ETA: Thanks to cs_whitewolf and lauren_b for pointing out the passage in CoS:
In CoS, at the end:
"You can speak Parsletongue... because Lord Voldemort... can speak Parseltongue. Unless I'm much mistaken, he transferred some of his own powers to you th enight 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."
And the more I think on it, I believe Voldemort is not able to share Harry's body because of the "power the dark lord knows not" - Love. Harry's love - and Lily's love - act like a shield for him. At first it was also a physical shield - Voldemort couldn't touch him. But by using Harry's blood to resurrect himself, he overcame that particular protection. Dumbledore certainly hinted that there were more, and we can't forget that gleam in his eye when Harry told him that Voldemort had taken his blood at the end of GoF.
As for another theory - I also think that Voldemort had the idea of using Hogwarts itself as a horcrux. It's certainly a very powerful magical object, infused with the magic of the four founders, and, it's very possibly sentient. If my theory about living and non-living horcruxes is anywhere near correct, just think how powerful he would be if he was able to tap into the power of Hogwarts itself! I think that is one of the main reasons why he was so eager to obtain a teaching position there. Only a theory, like my previous one above, but a cool one to think about :)