I am looking for a story I read a long time ago. It's a season 4 fic where Buffy gets stronger after she turns 19. She has sex with spike to see if she could still have sex with a human and Spuffy ensues. Any ideas how to find this would be greatly appreciated.

sclark
It sounds like you are looking for "Favours" by Palerider. It is on this site.

Tara