Everyone knows this story - Sirius arrived at Godric's Hollow, saw the Potters' bodies, and tore after Peter Pettigrew in a blind, thoughtless, reckless rage.

Um, except he didn't.

He tried to take care of Harry. He tried to get Hagrid to give Harry to him, and when Hagrid refused, he tried to argue.

What, you think he was planning to tear after Peter with Harry tucked under one arm? Of fucking course not. It didn't change that he wanted to kill Peter, that he probably would be happy to find and kill him later - but he wasn't planning to murder anyone, to throw his life away, to even sit in a dark corner and drink himself to death while holding a goddamn baby.

This is Sirius's godson, the person he promised his dead best friend he'd protect, and whom he now loved more than anyone alive. He's asking for the kid so he can take the kid, and that means devoting himself to a lifetime of raising, nurturing, being patient, being parently, changing nappies and nursing fevers and a million other VERY. RESPONSIBLE.THINGS.

Do we know how good Sirius would have been at doing that? Hell no.

But what we do know is the most important thing that he was willing to try.

Hagrid cites Dumbledore's orders and won't give Harry up.

So it's really only once everything is really gone - that Sirius's responsibilities and attachments are nearly all truly severed that he decides there's nothing else to do but go after Peter.