Under normal circumstances Wrath possesses very low levels of super-strength and endurance, just barely enough for him to qualify as "super". However, his power allows him to absorb the psychic energy given off by the "negative" emotions of those around him (such as anger, hatred, or fear) and channel it into his strength, endurance, and resistance to injury. Basically the madder those around him get, the stronger and more impervious to harm he gets.

Wrath is the definitive anti-hero, a tail-chasing beer-drinking foul-mouthed bastard. Fully aware of how his power works he will go out of his way in a fight to be as infuriating as possible. He will throw as many insults as punches, fight dirty, and otherwise do whatever he can to piss an opponent off. He will do the same thing to allies, every bit of their anger just adding feul to the fire. He actually does have good motives for what he does, but his methods often leave a lot to be desired.

When writing for Wrath I just try to imagine what I would do in a situation if I had no restraint or self-control and the power to back it up. The rest pretty much takes care of itself.