But I'm in so deep
Sirius didn't know where the bass came from. He definitely didn't remember it being in their dorms the day before, but today there it was, siting on Remus's lap with him playing it like he had been all his life. When Sirius asked him when he learned how to play, Remus grinned and shrugged how he does when he knows he's done something worth noticing, and said "I just got it yesterday. Same basics as a six string, really." and that was that. Sirius didn't ask him where he learned how to play a six-string, for fear that he might say something along the lines of "Same basics as a piano," or something equally as ridiculous.
That was four years ago, before the band, before graduation, before everything. The Marauders were a city-wide sensation now. Sirius was still feeling the same sensation he felt in fourth year watching Remus play bass for the first time.
It turned out that Remus actually did know how to play piano, or he learned it between then and James' first thought of "we should start a band." The same went for the ukulele, and the trumpet, a little bit of drums, and even the banjo for some unholy reason. James decided that instead of Remus playing every instrument in the band, that he would transfer his classical piano skills into playing keyboard (unlike Sirius, he enjoyed the lessons he had been forced into as a child, but that probably had something to do with the teachers). Because Peter never wanted to be left out of anything James did, he got Remus to teach him a few things on the drums (which was then a couple of overturned buckets and crash cymbals stolen from the marching band closet) and went on from there. This left Sirius the choice of lead singer or learning to play guitar since Remus's first live was the bass, but because the only real decision Sirius had ever made was moving out from his parents' house and also that he liked boys, he chose both. And thus, The Marauders were born.
It started off with covers, because how would they learn to play their own songs if they couldn't play others? They were so bad at first. They were so, so bad, they all shared a dorm together at Hogwarts Prep School so it wasn't like they couldn't practice. So practice they did, everyday. Remus would pick up one of they many instruments they had acquired by James's parent's money and he rest of them would follow suit. After those first few months, Remus would walk in with a piece of scrappy paper that had song lyrics on it when it was definitely supposed to have chemistry notes (out of all the things Remus was good at, Chemistry was not one of those), and they pieced together their first song. When they'd finally figured the basics out and played it most of the way through, James gave Remus a brotherly pat on the back and something like "we did it boys." Remus tried to hide a shy little grin at that but Sirius noticed because he always noticed.
Now they were out an about getting gigs all around town and even in the next towns over. They weren't on radio stations yet but occasionally there would be a store selling one of their t-shirts or CDs at the front desk and Sirius had to stop himself from buying one of each every single time. Peter had finally set them up a website after years of begging (he was the only one out of the four of them that took a computer class back at Hogwarts) and Remus had kissed him on the cheek in celebration. Sirius pretended that it didn't bother him a bit because it didn't. Remus had a right to kiss any of his friends that he wanted and it didn't even mean anything beyond friendship and it didn't bother him.
"-and they just click this link here and they're taken to our shop." Peter explained, doing all kinds of things with the laptop that he didn't understand.
"We have a shop?" Sirius's head shot up. He didn't even notice Remus behind him until he felt the taller man's breath on his own neck.
"We just went over this, Sirius, not even two seconds ago." Remus chuckled and Sirius bit down on his bottom lip, very glad that Remus was, in fact, behind him.
"Sorry, I was... I was distracted."
James looked up from his seat beside Peter with a raised eyebrow. Shut up, Sirius tried to telepathically convey to him. It was a long four seconds of eye contact and dancing eyebrows, but eventually James backed down with a shake of his head and a twinkle in his eye. It didn't bother him.