I read a comment that compared Spike and Faith and added that Spike wanted, for Buffy, to “make her feel” in SR. I'm finding an interesting difference between Spike and Faith. Her violence and aggression, especially when turned against innocents, comes from her trying not to feel, trying to avoid her own internal pain through denial and acting out. Spike is aggressive, at least in the beginning, because he's a vampire and that's what vamps do. He feels his pain and does not try to avoid it, but there is some denial going on. In Lover's Walk (that's the one where he kidnaps Willow and Xander, right?), he is in denial – he thinks he can get Dru back – and he is hurting others because of that denial but only because he thinks Willow can help him get Dru back. On the other hand, he is feeling that pain; he's not denying his pain.
I don't know what that says about the characters, if anything, just me musing as I have my breakfast.