AH heck, I'm going to kick myself, I know I am.
I can't remember the name of the fic or who wrote it. This is a rewrite fic, a long one, where Xander meets a drunk Spike, Dru was dusted in Prague, and takes him home, they become friends. Later on Xander develops psychic powers. He and Spike become lovers, and Spike helps the Scoobies fight Angelus for Xander's sake. Spike kills Xander's Father at some point. And Angelus gets his Mom. Oh and Ethan Rayne shows up and Giles and Ethan become lovers as well. Angelus kidnaps Spike. Xander and Cordelia rescue him.
Is that enough to go on?
It's driving me bonkers. I wanted to reread it and I can't locate it.