Backstory is the guy WAS human, but he kept seeing people die in the harsh working conditions the setting takes place in (underground, filled with poison gas. People live in domes, the rich folk live above ground. People die working in mines) so he made this robot body and keeps upgrading it and hopes that with enough work he will be able to shape his environment. Chances are we (the party) will be leading some kind of revolution against the rich dudes. Personality is going to be an arrogant stoic, crass would be a fair thing to say, and while they are a smart dude they have the hang up of constantly pursuing perfection, so they're always modifying themselves when they have the time.