One of my favorite characters might actually have an edgelord power now that I think about it. He's the priest possessed by a demon to save his family member or whatever, and he draws out its power by committing stuff among the seven deadly sins such as eating a bunch for gluttony or being prideful. He doesn't really act edgy though, at least not characteristically.

My duel vibrosword wielding half demon character runs on edge power so if he fights your guys he can absorb their edge power and activate "ow, the edge" mode where his vibroswords go overdrive.

For my red reaper and being a baby was mentioned, I was trying to think up a baby character but seems no matter what that idea is too stupid to attempt for real. For example, an ancient evil trapped in a baby body. A ten year old girl such as red reaper can still be taken seriously, but baby overlord can't. Who'd a thunk it? I feel like red reaper was a magical girl before turning evil, but that would be fan fiction of my own writing rather than factual.