7. Martian Manhunter Drives the Plot
If it wasn't set up this way, I'd say ditch the Manhunter in the first League outing. He's relatively complicated as far as story structure goes. When you've got to introduce all the members and a villain, and have time to give them all personality, Martian Manhunter becomes the tricky seventh wheel. But if his arrival to Earth is what drives the story, we can utilize him as reason to bring together the team. Superman acts as ambassador, understanding what it's like to feel different, etc. The League is made up of "freaks". Everyone is different but share common ground in that they are all dealing with some very specific and heavy trauma or loss. Martian Manhunter is a welcomed member because he is an alien who has lost his entire race, much like Superman. Public reaction to Superman is more friendly considering he looks like a human, but the Manhunter looks alien. His being unabashedly foreign would drive the public's perception of the League, especially if their initial fight is with the Manhunter, who may arrive on earth much like the Cloverfield monster; powerful, lost, afraid, and alone. The Martian Manhunter can be what brings the rest of the league together, gives them their first taste of team work, accepting J'onn into their ranks, and the desire to return him to his home world. It also means their learning that a far greater plot exists, which is what's partly responsible for bringing MM to earth... Professor Anthony Ivo.