(Obvi inspired by ATYD but a bit different)
Remus always managed to keep people at arms length. No matter who they were, he'd always kept some sort of distance from himself and them. It might be because he knew how they'd see him if they knew he was a werewolf, but Sirius, Peter and James knew that and didn't turn him away.
Whatever the reason, Remus knew that it just worked for him. He wasn't open and enthusiastic with new people like Sirius or James, despite not being as socially awkward as Peter. Remus was just...Remus and there wasn't much that could be said about him.
Unless you knew and acknowledged the fact that Remus was very gay for his very straight bestfriend in the 1970's. Sure, Sirius loved David Bowie and Queen but he also shut down all topics of them personally and focused on their music. His own barrier.
Remus had tried all the ways that he could think of to get rid of these unwanted feelings. He'd even taken up Sirius’s relentless badgering to finally go on a date with a girl. The date had lasted 15 minutes until she got sick of Remus trying to stay platonic.
Sirius had teased him relentlessly about it and honestly? It was quite calming that Sirius was just taking Remus's terribly love life in stride. Plus, it made it easier to get Sirius to back off from setting him up with anyone else for a while.
...until the night of Remus's sixteenth birthday. He wanted it to be normal like it was every year but of course the Marauders had to do something extravagant. This lead to a party being hosted in the Gryffindor common room with ever other house but Slytherin being invited.
Remus was reluctantly okay with this and had gone to the four boys' dorm to change. Only for Sirius to get closer than ever before. The lingering breath and harsh press of his lips was still sticking to Remus's brain.
He'd practically ran after Sirius, hoping for an explanation, his bad leg aching but ignoring it. Only when he got to the common room Sirius was tounge tied with a particular Mary McDonald. Oh.