harry potter

i have new theories:

okay, of course it is possible that snape is a death-eater and dumbledore was wrong. but...

hagrid overheard dumbledore and snape on the grounds, and they were arguing... snape was saying that dumbledore took "too much for granted" and maybe he didn't want to do what he had said he would. there isn't a clue about what this is, except that dumbledore says snape "agreed to do it and that was all there was to it."

this is what he says to harry when they are in the cave and he wants harry to force-feed him the liquid in the basin containing the horcrux. he had made harry promise unconditionally to follow any orders, especially those that would save harry's life and leave dumbledore in danger. when harry protests about having to make dumbledore drink this potion, dumbledore recalls harry's agreement to protect his own life over dumbledore's.

so... snape had to help malfoy kill dumbledore or die because of the unbreakable vow. perhaps dumbledore was ordering snape to kill him. dumbledore weighed his ability in the war against voldemort, and it came up short to that of harry's potential (because of the prophecy and perhaps some other talents dumbledore saw in harry). maybe he also weighed himself against snape, and saw what advantage snape could offer, having convinced voldemort of his loyalty...

this is a lot like a chess game, because victory is not won until either harry or voldemort (the king of either side) is killed. dumbledore was the most able wizard, but his death did not mean total loss. he was like the "queen," very versatile and powerful. he was sacrificed for, hopefullly, a gain. maybe, when he was pleading for snape at the end of his life, he was pleading for the end of his life. perhaps the potion was torturing him from within, and only death would relieve him. he had said that the person who drank the potion would not die, because voldemort would want to 'question' him. maybe the only merciful thing for the potion drinker would be death, and dumbledore knew that it would be best if snape killed him, to at least let snape stay alive and in the fight against voldemort.