Xu Jian

Transmigrated into the paper-thin bully Xu Jinyue, who's destiny was to die a pathetic death, long after the protagonist who does the deed had been betrayed and ran away to learn swordmanship and how to counterattack and whatever it is "underdog" protagonists do. Not ideal. Upon learning that the force who transmigrated him wants to see "truth", he immediately set out to drag his own reputation as deep into the muck as possible until he was the scum of the community his old body used to lord over. He's just being honest.

Unfortunately, his efforts to hitch a ride with some demons to escape the resulting abuse backfires when his saviour decides he wants to keep him as a pet. 

Xu Jian's body isn't designed to handle the powers he's coaxed his little system into giving him, and is subsequently constantly trembling no matter the context. His demon companions find it charming.

Was a homeless guy in his 30s in his past life, so he's generally pretty checked out and resigned to misfortune at any given moment. Gives him a buff to ruining his own life.