By his own admission, Renfield isn't much of a hero, having delivered victims to Dracula for years. He is disgusted with himself and has attempted to steer Dracula towards people who deserve it. He only sticks around because Dracula's trapped him in a codependent and abusive relationship. The second he starts to believe there is a way he can move forward without the Count, he takes it gladly. He's still pretty vicious with his fighting, but he fights for the right reason.