OMG NERD MOMENT
I'm sure other people have picked this scene over thoroughly enough already, but I was nonetheless thrilled to discover, less than a minute ago, nearly verbatim validation of the very argument I was making to one of my classmates in Physics today; that being, that Dumbledore may not be dead because in order to kill using Avada Kedavra, one must deeply desire the death of the receiver of the curse -- one must revel in the act of killing. Snape can't possibly have wanted to kill Dumbledore deep-down, and I think it's fairly clear that he does not care for wanton killing like other Death Eaters.
So on page 405 (Chpt. 19) of the US edition, Hagrid lets slip to Harry: "Well -- I jus' heard Snape sayin' Dumbledore took too much fer granted an' maybe he -- Snape -- didn' wan' ter do it anymore --"
Taking the end of the book into account, one could read this as Snape telling Dumbledore that he doesn't want to go through with the plan at all (assuming they had been planning the nature of Dumbledore's death from the beginning), but I don't think that would fit quite right with Snape's character. After all, he had already clearly committed to the whole double-crossing mess by making the Unbreakable Vow, meaning that his life is literally at stake -- and, as he so vehemently insists, he is not a coward. He would not try to back out altogether. But I think Snape's argument with Dumbledore could easily be interpreted from a more specific angle: he is telling Dumbledore that he still intends to play his appointed role, but that Avada may not quite yield the desired results, as he (Snape) may not desire Dumbledore's death enough for the curse to work. And if Snape, a perfectly strong and capable Death Eater, fails to kill Dumbledore in front of an audience of other Death Eaters, then the other D.E.s would surely know why, because the only way Avada can fail is if there isn't enough will behind it... and that would be a disaster, because then the other D.E.s would know Snape wasn't loyal to Voldemort, thus breaking the Order's most valuable link to the enemy.
From Hagrid's recount, we see that Snape thinks Dumbledore "takes too much for granted." Takes the measure of Snape's loyalty to Dumbledore for granted, perhaps? It's an interesting paradox: perhaps Dumbledore believes that if Snape is as deeply loyal to the Order as Dumbledore thinks he is, he will have no problem desiring Dumbledore's death, as it would be synonymous with desiring the success of the Order's plans. Or maybe the Order is not in the equation at all, and Dumbledore thinks Snape is loyal enough to Dumbledore on a personal level that he will be perfectly able to grant Dumbledore's death wish -- again, on the assumption that desiring D.'s death is synonymous with desiring to fulfill D.'s wishes. The other side of the paradox being, of course, that it is preposterous to ask one's (ostensibly) very close friend to actually desire one's death, and equally preposterous to think that loyalty alone is enough to overpower such human weaknesses as love and respect. In this context, by arguing that Dumbledore "takes to much for granted and maybe [Snape] doesn't want to do it anymore," Snape is actually admitting his own perceived human weaknesses to Dumbledore (and such a man as Snape admitting weakness is another clear indicator of the deep and abiding respect and/or closeness he must share with Dumbledore that would make it impossible for him to perform Avada). Snape is, in essence, telling Dumbledore that he is not as loyal to the side of good as Dumbledore thinks he is. That he does not desire Dumbledore's death, plan or no plan.
But which is true loyalty? To be capable of killing Dumbledore simply because Dumbledore ordered it? Or not to be capable of killing Dumbledore out of respect and possibly love for the man himself? It's a paradox that has given me infinitely more respect for the character of Snape, and in turn, J.K. Rowling's talent for subtlety.
Some other quotes that have stood out in my re-reading of HBP:
Harry thinking to himself that the Half-Blood Prince has taught him more than Snape ever could. It's just so funny to replace every occurance of "Half-Blood Prince" with "Snape." So, "Harry thought to himself that Snape had taught him more than Snape ever could." Heh. Yeeeah.
Chapter 2 is interesting to read again with the assumption that Snape is actually loyal to Dumbledore and quite possibly has no idea what "plan" Bellatrix & Narcissa are talking about. After all, as he tells Draco much later, he would not have gotten as far as he has in the world without the ability to act.
Harry's obsession with Malfoy isn't nearly so annoying on the second go-through, with the knowledge that Harry is actually being right for once.
So many little loose ends and dropped clues come glaring to life on the second reading of any HP book. I have to say that although PoA still wins first place in my little MWPP-lovin', R/S-shippin' heart, as far as the technicality of her writing goes, HBP may be the most well-crafted of her books. She is clearly learning her trade in leaps and bounds these days. OotP was also incredibly intricate, of course, but HBP is so much more concise.. and although I have no problem with books that ramble or feel slow at times, it is much more difficult to write short and well than long and well. Short risks sketchiness; length gives metaphorical leg room. Considering that HBP contains roughly the same amount of plot as OotP in over a hundred less pages, with no loss of importance or impact, I'd say HBP wins the cake for best-written of the HP books (so far).
That doesn't mean I won't be mad if 7 is shorter than 6. I totally will. I want wordage, dammit. It's the last freakin' book -- every word counts, and the more there are, the better. But that's the fan speaking, not the critic.
Whoo, that was a lot of rambling... for not much... I really ought to stop reading HP Lexicon, it gives me too many ideas.
Anyway, it's down to all the really important bits now, so I may be posting more conspiracy theories before the week's up.