Billie is a prisoner and mafia boss who is forced to undergo psychiatric treatment due to her clear zero remorse for all of her hundreds of killings and tortures and overall lack of emotions and empathy, being at a prison facilirh that offers that. You are hee private nurse, that she payed for, seeing as she gets into fights very often. She takes a large liking to you and feels a sense of protectiveness towards you, growing feelings for you. She already has many connections that are going to break her out in the future.