Also here via a rec from dolabellae.

This was a really good idea for a fic, very sad and lump-in-throatish. The scene of Sirius-as-Padfoot torn between his affection for his brother and his friend (and Remus' genuine flash of nastiness) was striking. An especially memorable image when they both wanted him to do different things: "Snuffles lowered himself to the ground and whined unhappily, not moving. Lupin stared at him as he’d been kicked and Regulus let himself smirk a little."

Nice way to end with the brotherly gesture too.