I was tempted to play Aqualad, only because I'm such a big fan but I don't know hwo I would go about playing him since not much was explored with him in season 2. Also, I have an interesting OC villain that isn't very power-based but more.... Dangerously intelligent then anything. He basically has a helmet that's hooked into his brain. It's basically a supercomputer that downloads information into his brain, and forces his brain to function at maximum levels, making him dangerously smart. This allows him to perceive many possible happenings before they happen, like getting punched in the noggin. He isn't the type to brawl out, play fisty-cuffs or exchange low for blow. He's a scrawny guy with too much imagination, imagination that's coming to life. Anyways, he could probably perceive one of the hero's about to kick his ass and no every maneuver they would use to do so..... And still let them do it. Why; because he isn't a fighter, doesn't know the first thing to do.
His motivation would be that humans in general are becoming too dependent on Hero's to save them from the villains. He's an ordinary guy who's trying to solve that problem, give humanity some self respect in consideration to their dependency. So, his first act is to kill a superhero, some one well known to alert the public that HERO'S CAN DIE! What do you think of that idea and gradually building off it? Character and motivation.