Writing is rewriting, but I don't have time for more than a first draft, so apologies if this is more than usually lame or incoherent, but I'll at least keep it short.
My Essay on Spike
As I've said, I think one of the glories of BTVS has been the transformation of Spike over the last few seasons. I'm not going to argue the skill-or lack thereof-with which this was handled-you enjoyed it or you didn't. Instead I'm going to give my view of the nature of the transformation.
In season 5 we find Spike falling in love with Buffy. At first this is presented as just desire, but by the end of the season is something more-and it extends beyond Buffy to the "Summer's women." (Spike's grief for Joyce is real, as is his affection for Dawn.) In season 6 Spike is suffering from tremendous guilt over having failed to keep his promise and in the process save Buffy. This is important: Spike has no soul but he is already capable of guilt. It isn't a general guilt for his crimes, only for his failure to save Buffy (when it counted). But it is something Angelus, even with a chip, could never have felt. It is the "stink of humanity" the Judge felt in Spike even in season 2.
And then when Buffy returns she instinctively turns to Spike-he is both the only one of the Scoobies (except Dawn) not involved in pulling her out of heaven, but the only one who can understand returning from the dead (though not from Heaven, which is Buffy's knowledge alone). And it is because of this Spike has to be the one to save her from suicide by dance in OMWF.
And now things change. Buffy needs Spike-his desire for her connects her to Life in a way nothing else can. But he is still a vampire, who might never harm Buffy or Dawn but would certainly feed on others if the chip were removed. The demon in Spike is oddly incomplete, but it is still there. Spike, whatever he is, is not Angel. And so Buffy is disgusted by her own need for him. She first sleeps with him in the middle of a fight-and she is the one who turns it from violence to sex. And she continues to treat him with contempt. As she later admits, she uses him-and in doing so she feeds the demon side of his nature. Perhaps nothing she could have done would have encouraged him along the path to true redemption, but her behavior instead encourages him to try and pull her over into the dark. (But I agree with those who say that doesn't mean he would ever want to Sire her-he is in love with The Slayor, not a demon version of The Slayer.)
Until finally she realizes what the relationship is doing to both of them and ends it. Spike tries to accept this-at Xander's wedding he is clearly making an effort. But he can't. And then the comes AR.
Which is not at all planned out. Spike doesn't go there to rape Buffy, and doesn't think he is. That isn't to deny that it IS an attempted rape, but in Spike's drunken, desperate state it is simply another one of their twisted sexual encounters-sex through violence. When Buffy stops him, only THEN does he realize the difference, realize the line he has crossed. And again showing that his demon self is different from other vampires, he is horrified by the realization, and flees.
And now for the second time he feels guilt. But he is a creature without a soul-how can he feel guilt? It's the chip's fault. Spike's remark on leaving Sunnydale is a misdirect, but a fair one imo, because I think Spike IS telling himself when he leaves that he'll have the chip removed and be the monster he was meant to be. The writers are misdirecting us, but legitimtely because Spike is lying to himself as well as us.
Lying to himself because it isn't the chip that has allowed him to feel guilt-it is love, the capacity he showed the Judge long before the chip. There are those who say that his being in love with Buffy undermines his redemption arc-he's just doing it because he wants Buffy. But all good can be reduced to selfish motives (if I give my life to save someone at some level I have a "selfish" motive for doing so, unless the action is unitentional and instinctive). And the point is that Spike's feelings for Buffy are not just desire-thwarted desire alone doesn't provoke guilt, only rage and frustration. However limited by his demon nature, Spike feels love.
I'm not sure what his conscious self was telling him when he was in that cave. But I don't think it matters-whatever he was telling himself, the self he was telling it to didn't want the chip removed to kill Buffy, he wanted to be worthy of Buffy. So when in Beneath You he tells Buffy he went to get his soul to be the sort of man who could [never rape her] he is telling the underlying truth, whether he admitted it to himself at the time or not.
And that is the key-Spike's capacity for love and guilt drove him to get his soul. That doesn't erase the AR for either of them. But it puts it in a different context. Spike has done the unheard of-a vampire not cursed with a soul but obtaining one. Buffy-who knows full well the differece between a vamp with a soul and without-knows Spike's true redemption is not achieved but is now possible. And being Buffy, she can't stand on the sidelines of that struggle (which in the context of the battle with the First Evil has tremendous implications-corrupting Spike is a major goal of the FE all season; a redeemed Spike has to be the ultimate insult to the FE, while an evil Spike is a potentially powerful weapon in its employ). That is why Buffy fights so hard to keep Spike alive, why she refuses to stake him or allow Giles or Wood to do so.
Does watching-and indeed participating in- Spike's struggle spark other feelings? Probably; she isn't in love with him, but Buffy is intimately involved in Spike's path to redemption, and intimate feelings can be hard to keep in clear channels. Certainly Spike's feelings for Buffy threaten to spill over into sexual desire. And that is the FE's last hope-th