Growing in a troubled home, Harleen was always smart, but lacked attachment. She achieved her doctorate and started as a psychologist in Arkham Asylum, where she earned a reputation as being excellent at her job, until she was assigned to the Joker. Over their sessions, Joker broke Harleen mentally, making her as insane as him, and making her lovesick for him. Becoming Harley Quinn, Harley spent a year as the Joker’s right hand, before getting free of him and becoming a violent hero for good.