Demon Man is one of the ultimate pieces of shit. He runs around with a demon mask over his head and screams "DEMON MAN!!!" right before he kicks you in the nuts and then proceeds to run away laughing. It is not known where Demon man derives his powers but with further research scientist realised that he doesn't really have any.
An interview was requested with Satan to see if he knew anything about the masked Menace but reporters were to told to go away. This angered them and as they tried to leave they found they could not and were soon told that they belonged in hell.
The true origins of Demon Man may never be known or any of his powers but do you really care?