(1/2) I have a headcanon that Dean knows how to play either the guitar or piano. Like he was forced to take a music class for some reason in high school. They had a lot of instruments in the music room but the only thing that got Dean's attention was the guitar/piano. Maybe because John or Mary used to play one of the instruments and it reminded him of happier times. So he starts to learn how to play and he just falls in love with it. But they leave about a week later
(2/3) So basically whenever they get to a new town and he and Sam enroll to a new school, he checks whether or not they have a music room or at least those instruments. Or if there’s just a place where he can practice in peace without John or Sam ever finding out. He even plays some gigs and earn some money for him and Sam. Fast-forward to him and Sam in the bunker. He buys a guitar/keyboard or piano while Sam is gone and puts it in a room he’s pretty sure Sam won’t find. (Whoops not done)
3/3) (last part I swear) So one day he’s down in that room playing (because by this time he’s really good at it) while Sam’s out on a supply run. As he’s playing this really hard piece, Sam (or Cas or both) come back and try to find him. As he get closer he hears the music and finds Dean playing the guitar/piano. He just kinda leans against the doorway and smiles at Dean. He doesn’t say anything until Dean’s hit the last note/chord and even then he just starts to clap softly.
Ugh. YES. THIS. SO MUCH THIS.