DXD: Biokinetic Devil

Julius Mercer is a mixed-heritage devil. His father and mother were both humans that had been reincarnated into the Lord and Lady Sitri's peerages respectively, so he'd grown up taught to be respectful to pure-blood devils and ensure he didn't make too many waves. His father died shortly after he was born, but when his mother came down with the Sleep Disease, he decided he wasn't going to sit quietly and live a mediocre life as a mixed-heritage devil. He'd get strong, he'd cure his mother, and he'd have life at his fingertips.

MC is going to develop his demonic power into Biological Manipulation. He isn't going to join a peerage, and I'm going to try to develop more of the underworld beyond just the pure-blood houses that most use. MC is the studious type, by need more than anything since his power is so rooted in biology.