I'm looking for a Spander fic...the particular scene that popped into my head today that won't leave is this: Xander takes Spike to a company party (maybe Xmas?). Spike gets jealous and says something inappropriate. Xander gets mad and leaves Spike at the party. Spike gets a ride home from a friend and decides he doesn't want to live without Xander. He waits on their porch for the sun, Xan saves him just in time. Hot sex follows.
I seem to remember it is a longish fic, but can't remember any other specifics.