User blog comment:Dtuck010/Theory why Nightwing, Miss Martian and Superboy didn't want to join the League/@comment-4454131-20120429025018

to me it feels right that they stayed with the team instead of joining the league and that it isn't really a good time for them to join the league what with the public and alien issues directed specifically at the league. I think one of the main reasons is probably that the team has come to mean alot to them even though the others (possibly asside from those we haven't seen yet) have moved on and joined the league. They're happy being mentors to the new members in a way they feel is right, a change in the teacher/student relationship the team had with members of the league, best seen with how they mirrored the end of fireworks with a contrast between how Batman reacted back then and how Nightwing did in Happy new year. Besides, I'm pretty sure Nightwing never really spent that much time with the justice league in the comics anyway.