Top Ten Things Writers Need to Remember When Writing the Martian Manhunter
7. J'onn J'onzz likes Earth.
For a minute, put aside all that cone-headed post-52 full-body-suited goth version of the Martian Manhunter. Clear your mind of all that angsty "why should I help humans" nonsense.
Are we clear? Good.
On more than one occasion in his Silver Age appearances, J'onn had the opportunity to leave Earth. And he always chose to stay, either because he wanted to keep helping us, or because he remembered his Earth friends, or because he just wanted to do the right thing. You know, heroes did that back in the day: sacrificed their own needs to serve the greater good. It's kind of the definition of the word "hero."
J'onn chooses to apprehend a criminal rather than escape back to Mars. What makes this even more impressive is that this is from an early appearance, where no one even knew who the "Martian Manhunter" was--he hadn't yet gone public as a superhero, just used his powers covertly to solve crime. He hadn't gotten any public adulation, just everyday human decency and friendship, yet he still considers Earth a welcoming (albeit lonely) place.
Detective Comics #267
Whereas I would've been like, "Screw it, I'm going home to my family and my dog," J'onn takes the high road because he's a class act.
Bottom line: he likes Earth. He likes Earthlings. He considers Earthlings his friends. He wants to help Earthlings. Got it? Good. Now don't forget that. And don't let any emo-body-suited Martian Manhunter impostors tell you otherwise.