This is vivid and real and heartfelt! I adore that you didn't gloss over Sirius' pain or that he was entitled to it. They're both damaged and needy men here. So that makes it all the sweeter as they bring the problems into the open and begin to get closer.
I adored the lovely kiss at the end. &hearts But where I really had that heart swoopy feeling was here:
He snapped his eyes open when Sirius sighed and moved his body closer to Remus's an inch.