Aw well do you know 'Magnetized Alignments', the AU fic by rev02a? There, Sirius plays a violin (?). It's the best thing EVER. I think that, due to Sirius' home, it would be perfectly possible if he did draw or play an instrument. So don't you get bothered by that! Just write it the way you want to and you'll see it's going to be wonderful :)

ZOMG I LOVED THAT FICTION. DUDE IT WAS AWESOME. do you have, by chance, more all-time favs? i think i might love them