Check out my jeanmarco fanfic "i am not who i was" on ao3! (my user on there is marcipeach)
Summary:
During their high school years, Marco encourages Jean to follow his passion and pursue music, which ultimately leads Jean to leave Marco behind when he joins Eren’s band after graduation. They have a bittersweet goodbye before the band goes on tour for who knows how long, and Jean promises to return to Marco someday. Marco just encourages him to go for his dreams, he’ll still be around when he comes back.
Several years later, after seasons of touring, fronting for bands barely bigger than themselves, random gigs, and odd jobs in between to make ends meet, Jean finally returns home to Trost. After a somewhat awkward reunion with Marco, the two are happy to be back in each other's lives. Despite this, Jean is hesitant: he's not the same kid Marco remembers from back in high school and he doesn’t know if he fits into his old life the way he used to.
