I could have sworn this fic was on the Spanderfiles, but I can't find it! In it Buffy and the others (during the apocalypse with the First, maybe) send Xander to LA to pick something up. But Angel lost his soul and none of the LA Gang think to tell the Scoobies. So Xander is at the hotel alone and Angelus finds him. Angelus tortures Xander and turns him, but Xander gets free and takes revenge. He steals a car and drives it halfway to Sunnydale before collapsing and Spike finds him. Xander calls Spike his Sire and Spike agrees.
Does anyone remember this fic from my rather lengthy description?