Hard shell soft core, grumpy, depressed, pessimistic, introverted

He's pessimistic and depressed most of the time and doesn't try to hide it. Yet he manages to mix it up with dark jokes, sarcasm. Has slight anger issues. He gets upset and offended pretty quickly. He has suicidal ideation. He's firm/stern.
Had an abusive father in his human life.
Revenant used to be human. He used to be the greatest hitman the Mercenary Syndicate ever had. 

He was experimented on as a human and as a simulacrum.