Harleen Quinzel was a brilliant and successful criminal psychiatrist. After encountering the criminal mastermind, The Joker, at Arkham Asylum, Harleen develops a fascination with the madman's maniacal psyche. She begins to treat him, only to find herself completely under The Joker's control. Unable to break his hold on her, Harley enters a world of crime as The Joker's criminal accomplice and lover, Harley Quinn. Harley quickly becomes one of the Dark Knight's deadliest enemies, as she carries out The Joker's every evil whim. She develops a villainous friendship with Poison Ivy and the two become sisters-in-crime by virtue of their shared hatred for male domination in the criminal underworld. Although her true personality has been subjugated by The Joker, beneath it all Harley remains a sweet lovable person. Upon her arrest, she is deemed mentally unbalanced and sent to Arkham Asylum - not as the brilliant doctor she once was, but as one of Gotham's criminally insane on the other side of the padded cell.

Mainstream: The love of a bad man made Harleen Quinzel what she is today: CERTIFIABLE. While researching Arkham Asylum's lunatic fringe, the ill-fated psychiatric intern met the model murderer, the Joker, and fell for him head over heels. When the authorities discovered that Harleen aided the Clown Prince of Crime's all too frequent escapes, her medical license was revoked...and Harleen was given her own padded cell from which to pine over her "Puddin'." Freed from Arkham after Gotham City's cataclymic earthquake, Harleen made herself over in greasepaint and tassels. As Harley Quinn, she was the perfect partner-in-crime--a curvy jester who delighted in mayhem as much as the Joker. However, the Ace of Knaves quickly tired of Harley's affections and gleefully shot her off in a rocket. Crash-landing outside Robinson Park, Harley was nursed back to health by Poison Ivy, who administed an herbal significantly enhanced Harley's strength and agility, while making her immune to most toxins. Reconciled with her "Mr. J," Harley hopes to lead him to the altar.