Your muse's madness is genius!
Wow, this is exactly the kind of dark angsty hurty sex that works! It's such mad hurt it turns the corner into comfort, and it's almost scary that I can't see where that corner was. Scary for Sirius and Snape, too, I think. But it works out. Who rescues whom? Anything after this is going to be insanely hot! No question that Snape will be back. :D
Pulling this off well is so rare! This is deftly written, sexy, IC, and deeply thoughtful -- you only scare me a little bit there. Let's say, anyone who can write this is in Snape's and Sirius's league. *eg*