Harley BG

Toxic Immunity: As a result of Poison Ivy’s treatment, she is immune to various assorted toxins (including small doses of Fear Gas) and Ivy’s own poisonous touch. Her constant exposure to Joker Venom has also made her immune to its effects.

Gifted Intellect: Despite being somewhat absent-minded, she is shown to be highly trained in psychiatry.

Trained Psychiatrist: Harley completed her psychiatry residency at Arkham Asylum, and is now a trained psychiatrist in both fields of psychoanalysis and criminology.

Expert Combatant: Harley Quinn is a highly skilled combatant due to her years as a criminal and uses her skills in gymnastics to help her in her fights.

Master Acrobat: Harley's skills in gymnastics rival those of Catwoman and Nightwing.

Enhanced Strength & Stamina: Harley's strength and stamina has been augmented by injections given to her by Poison Ivy.

Harleen Frances Quinzel was the oldest of 3 children born to Nick and Sharon Quinzel, followed by a sister, Delia, and a brother, Barry. Coming from a less than perfect home, she helped raise her younger siblings when her parents were fighting or out, basically becoming their second mother. While she tried her best to be a good example for her siblings, years of being ignored and pushed aside by her parents and others made her a trouble-maker.

Dr. Quinzel was a noted psychiatrist at Arkham Asylum, who volunteered to treat the worst of the worst, The Joker. During their sessions, the doctor quickly fell for the Joker's charm and charisma, falling in love with the noted villain. So enamored was she that she took up the mantle of Harley Quinn, The Joker's right hand woman and lover.

During this time, Harley had a daughter by the Joker, but he never noticed and she never told him. She named her Lucy, but to keep her safe from Joker, Harley left her with her sister Delia to raise as her own. After about a year, Harley returns to the Joker’s side. He never noticed her absence.

After years of abuse, both physical and mental, Harley finally had enough and dropped the maniacal clown like a sack of moldy potatoes. Once she got paroled from Arkham, she fell off the grid, and stopped reporting to her parole officer. Harley wanted to start fresh, and having the parole board breathing down her neck wasn't ideal.

Making sure she was in the clear, she set up shop in a condemned building, applying to as many jobs in the medical field as she could. All of them were rejected, saying they had policies against hiring convicted felons of the super villain variety. Every other request was for more unsavory jobs, which she wasn't desperate enough to take.

Eventually, Harley gets tired of the constant rejection, and goes on to start up her own thing.

Harley starts advertising herself as a mercenary and private eye, handing out business cards stating such, and actually gets some traction in the field. Using the skills she’d gathered over her years as a villain, she helped anyone who came her way, usually for very modest fees (supplemented by the occasional theft of items from other unsavory types). With time, her sense of self and her confidence grew, and she became a notable force to be reckoned with. Even teaming up with the occasional super hero here and there.