Gen, or any pairings you want. I just want these guys blogging, tumblring, writing RPF avengers fic, being each other's betas, commenting on each other's posts, etc etc. maybe they know each other irl but don't realise who they are online, maybe they meet online, maybe one of them introduces the others to fandom....
Everyone, social media/fandom
bonus points for if the whole thing's epistolary