In the beginning

[suehpfan]

No: HPFGUIDX 91980

 Sue here:
<SNIP>
they (Harry and Voldemort) were in "essence" sharing the same 
life force.  "Neither can live while the other survives."
Max:
For instance, it would explain how Harry appropriated various skills
from Voldemort. <snip> it might also explain why Voldemort's body was
never found. Perhaps it vaporized once most of the life force was 
sucked from it. (Although V was obviously able to retain enough life 
force to remain a bodiless entity.) And to take an even wilder leap, 
it might also explain why Godric's Hollow was reduced to a pile of 
rubble. 
snip 
> Siriusly Snapey Susan now:
> Okay, Max & Sue.  Can you go a little further with this theory?  Can
> you explain how you see the conclusion?  This almost seems to
> necessitate Harry's death in the end, does it not?  
> 
> Siriusly Snapey Susan

Here's what I think...Voldemort was not "supposed" to survive what 
happened in GH.  His time was done.  Unfortunately, what 
ever "dangerous transformations" he underwent prevented his death as 
we understand it.  Voldemort is a sort of parasite, sharing 
Harry's "life force" and even drawing it from him, the longer he 
maintains a body the more entwined Harry and Voldemort will become.  
In the end Harry will have to extract himself (and all of the "life 
force") completely from Voldemort and when that happens Voldemort 
will die (really this time).  

Based on how I see it, if *Harry* were to die, that would mean 
Voldemort would go on to live for a very long time.  Harry has to 
survive and keep the "life force" within himself in order to save the 
WW from a long reign of terror by the "Dark Lord".  In the end, the 
battle (as other posters have also written) will take place inside 
Harry's head or on some other plane and will envolve the force of a 
sort of "mental Patronus".

As I said before, this is way far fetched and I'm not even sure I 
believe this is how the story will end.  I just find the idea of them 
sharing a "life force" intriguing.  Imagine what Harry could learn 
over the next two years right inside his own head.

Sue, who would never suppose to have any clue how JKR thinks.  For 
me, Filch was kicking the students across the swamp and the Griffin 
knocker was just a decoration :P.