First post so please excuse me if I'm breaking etiquette.
As has been said before, regardless of his having a soul, I think Buffy and Spike would still have developed a physical relationship, perhaps not one that could demolish buildings so efficiently but still. Buffy sought Spike out, I think, because of her self-hatred, her wanting to self-destruct but also because being with Spike is the only time she felt anything, even if that was the primal urge of sex. Her friends wanted her to be 'Happy to be alive Buffy' and Dawn wanted her to be 'Supportive sister, breadwinner, normal Buffy' while all Spike wanted was her. He wanted her in any form, any shape and any circumstance. Yes as the season progresses he does gripe about the fact that he wants more than angry, sexual intimacy but she knew that his love and obsession would allow her to be whatever she wanted with him. It sounds mean because I think season 6 Buffy was mean, but she knew she could do whatever the heck she wanted to him and he'd still be there wanting more, he was willing to put up with all the abuse and that's what she wanted, someone to tell her that no matter how bad you get, I will still love you, just as Xander did for Willow when she found a very convenient doomsday device in a hill at the end of the season.
So while I've gone off on three different tangents what I meant to say is that Buffy and Spike's bond came from them both being "creatures of the dark" he was obviously non-human and that's how she felt. Whereas if he'd had a soul I think they would both have bonded due to the fact that they've both been expelled from "heaven" - Buffy thinks she was torn out of Heaven while Spike would have had the heavenly bliss of no conscious niggling away at him about all the people he'd killed, suddenly taken from him. Buffy would have to relearn how to live again, how to feel the pains of everyday life and Spike would have had to cope with his new found guilt and felt as is he was in hell too. They would both have leant on each other to cope with all their new guilt - Buffy's guilt of wanting to have remained dead and Spike's of having killed victims he found in coalbins etc.
And I think Spike would still have let Buffy use him to a certain degree because he too would have wanted to be wanted. They would have had sex and instead of him telling her that she was bad to the bone like him as he actually did, he would have said, "Well that was nice, pet. Made nicer by the fact that we are such awfully nice people!" Seeing Red culminated in an attempted assault, had he had a soul I think it would have perhaps ended on them being emotionally where they were in Season 7's Touched, on the cusp of her realising she loved him. Or perhaps that's just where I wanted her to be at the end of season 6! Stupid Buffy.
