"I'd just to like to say, if there were no Batman, there'd be no Joker and I never woulda met my Puddin!! Thank you, Batman!"
Harlene Quinzel was a brilliant and successful criminal psychiatrist. After being assigned to the Joker, at Arkham Asylum, Harlene developed a fascination with the madman. She began to treat him, only to find herself completely under The Joker's control.
Having been Joker’s therapist for a given amount of time, Harley was at least partially responsible for his many escapes from Arkham. Doctor Arkham discovered Harlene's secret and revoked her medical license and committed the lovesick girl to the asylum on the spot.
In the aftermath of the 7.6 earthquake that struck Gotham City, the Asylum's security system went haywire and Harlene's cell simply unlocked. Quinn ventured to the outside world, ignoring the devastation caused by the quake, on a crusade to find the Joker. One ransacked costume shop and a fitting period later, Harley found her man (much to the Joker’s disappointment). Harley enters a world of crime as The Joker's criminal accomplice and lover, Harley Quinn.
Harley quickly encountered Batman, as she carried out The Joker's every evil whim. But after a while, Joker got tired of his annoying girlfriend and tried to kill her.
Poison Ivy found Harley in a bunch of rubble nearby. Feeling that she had nothing better to do, Ivy took the costumed Harley back to her hideout. Isley soon realized that under the mask it was the old psychiatric intern from Arkham Asylum, Dr. Harlene Quinzel. Hearing Harley talk about how she didn't want to live, she figured there was a good story behind Harley's babbling. Isley listened as Harley Quinn told her tragic story of how her 'Mistah J' betrayed her.
Angered, Harley Quinn vowed that she would get him. Ivy felt sympathetic for Harley and gave her a special drink that enabled her with special agility. Now more powerful than ever, Harley set out to destroy her old 'Mistah J.' She fought with him for a bit, and traded punches with the Dark Knight. Knocking Joker off a ledge, he asked if they could go back together. Harley immediately excepted and hoped back into her Puddin's arms.
In Lost Souls San Francisco, Harley is once again practicing medicine. There are just so many people in the city by the bay that need a little guidance now and again. And well, it is a great cover for other less savory activities.