"You can call me Harley! Everyone does!"
Harlen Quinzel was a psychiatric intern at Arkham Asylum. Despite receiving high grades in college, he was not a particularly intellectual or strong-minded man, having only gotten through college by seducing his professors. While researching the lunatics at Arkham, he became fascinated with one particular inmate. Ambitiously volunteering to analyze him, he fell in love nearly instantly with the Joker during their sessions. After helping him escape from the asylum more than once Harlen was suspected by the authorities, who revoked his license and placed him in his own cell. During an earthquake in Gotham City, he fled and became Harley Quinn, the sidekick to the Clown Prince of Crime himself, The Joker.