Spike makes buffy drink something that makes her temporarily not human

Hi, I think this fic might have been set around 'Crush'.. but I remember that while Buffy is unconscious Spike makes her drink something that makes Buffy temporarily not human, so Spike can bite her. Spike tells her this when Buffy wakes up chained up in Spike's crypt.

I don't think it was too long either, & it would've been completed

It's "Handle me" by Greyangel

That's it, thanks!