Filthy Sirius. I never did like him. In fact, I would have to say that in the books I was happy when he died (although I was certain that he would come back out from that veil before the end of the series).
I'll admit my position changed quite a bit when that bloody genius Gary Oldman got involved.
This is why I avoid Marauder fics. Snape was humiliated and bullied and lost his only real friend, and because of it he was seduced by Voldie. Not that Severus is free of blame, but James and Sirius certainly made a bad situation worse.
I've got to keep reading just to see if/how you can bring any light into those dark times.