Spike buys Buffy at a slave auction. Can't remember anything else useful in looking for the fic myself, but does someone else know it? BTW, Spike is a vampire and Buffy is the Slayer.
EDIT: I knew I didn't have enough details, but I can't quite remember if Spike is in love with Buffy and she doesn't know it, doesn't believe it, or if he isn't in love with her, or if he loves her but has to pretend he doesn't while he's buying her. I do remember Buffy did not have a plan and expect him to buy her, and she was definitely not happy about being sold. does that help? Otherwise, I like all the fics being mentioned as possibilities, so don't hold back on commenting!
EDIT: I knew I didn't have enough details, but I can't quite remember if Spike is in love with Buffy and she doesn't know it, doesn't believe it, or if he isn't in love with her, or if he loves her but has to pretend he doesn't while he's buying her. I do remember Buffy did not have a plan and expect him to buy her, and she was definitely not happy about being sold. does that help? Otherwise, I like all the fics being mentioned as possibilities, so don't hold back on commenting!