Harley Quinn is the younger sister of Deandra Quinnzelle. Both grew up in a fairly normal household. However, both girls grew bored with their lives at a young age which caused Deandra to frequently break the law simply because she could. Harley on the other hand, although she followed in her sisters footsteps in finding more “off the wall” activities to quell her boredom, had more finesse in her strategies at getting what she wanted. Both sisters learned at a young age just how susceptible people were. While Harley used that knowledge to better understand the psychology of humans to further benefit from, Deandra was more intrigued to understand it from a personal level, for instance often taking drugs herself to understand what happens in the mind of addicts.

As Harley got older she majored in Psychology, with a minor in Women’s Studies. Along the way she had a few boyfriends, all of which claimed she had a tendency to “control” the relationships with a few assault charges thrown at her after they broke up with her. At one point in time an ex-boyfriend mentioned her love of violence in film, TV, and comic books to be “over the top.” Harley saw that not only as a threat to herself, as someone who doesn’t take kindly to any form of critique or judgement, but also saw it as an extremely sexist remark because his male friends were similar, according to her. One of the major things she observed in the culture around her was an apparent double standard between men and women. Something she would always keep in the back of her head.

Once she was a psychologist for a few years she felt a lack of purpose inside her. “Helping people” was never something she had any interest in, nor was money, both of which were the two reasons she found most of her colleagues to be in this line of work. More and more she gradually realized just how much she didn’t feel the point of this life. Then one day it hit her. The closest thing to fulfillment was her strong desire for power. The feeling of having complete control over the world around her brought her a sense of not only euphoria, (she knew that was only temporary) but something more. She felt as though she belonged in that seat of power. All would feel right around her she thought. No more anger at this world.

That feeling came one night when she saw a couple of criminals harassing a couple in a dangerous alley. Feeling this moment had finally come she stepped in to the scene and singlehandedly made sure the villains got what they deserved. The couple was shocked by her brutality and ran off. Although Harley was never one to strive to be a hero, that feeling of fear she received from the couple turned from anger at their stupidity and unappreciative attitude to one of triumph. Her power was terrifying. And she loved it.

Her exploits at killing off those she found no one would miss became a regular part of her life, and soon she became less selective on just who she killed, not just settling for the worst of the worst. If anyone even annoyed her she would make sure they would regret it. It was during this time she got laid off from a psychology job due to “an overabundance of workers” which she always thought was a manufactured excuse.

However, she used this time to explore other career paths such as being a TV personality on a local show offering advice from a certified psychologist to guests, however, that didn’t last long. However, despite this drawback, she realized the power and influence she had in the media spotlight including the fakes in the industry taking in the majority of the money.

Eventually, she finally found a new job. One no one else wanted but simply drew her more in: A psychologist at a psychiatric ward. She felt, although would never admit it to her coworkers for fear of losing her job, that she felt a connection to the inmates. A sense of being lost, no purpose, no meaning. She found one patient in particular, was almost afraid of his true self and personal power. This patient was a cop by the name of Jack Daniels. Harlene (she went by her full name at this institute) and Jack got along better than any other patient-psychologist in the building, and Jack’s quick recovery to happiness was even applauded by her superior. However, most of her other patients had a record of ending up in worse shape. Martha Wayne during her annual review found several of her clients to become blind followers of Harlene. Martha attempted to explain to Harlene that she was abusing her role as a Psychiatrist, Martha eventually Brought this to Thomas Wayne. Thomas being a doctor perceived this as a gross abuse of the doctor/patient trust. This in turn, led to her termination as the Wayne Foundation, who previously gave her grant funding, said they would cut funding to Gotham Social Services, unless she was let go.

Angered by her perception that her dream job being taken away from her by Thomas and Martha Wayne, her anger toward the Wayne’s intensified beyond anything she had ever experienced. It was this anger that truly brought her over the edge in her now apparent uncaring attitude. It was also during her times with Jack that led her to truly feel something powerful for somebody else.

After Jack Daniels had discovered his partner was a dirty cop Harley helped take him down, resulting in Jack’s first murder. During this time Harley and Jack truly felt happiness. All the while Harley would try to bring him closer to his full potential. It was that night Harley gave Joker the nickname, Joker, for she felt that title suited his true chaotic personality.

Harley's obsession with the Wayne's resulted in her seeking out the long time rivals of the Wayne's, the Dumas. Harlene was hired to be an advisor after passionately describing her hatred for Thomas and Martha Wayne. During this time Creel Galavan-Dumas hired Harley to carry out an act of revenge after Creel was injured in a light sabre battle with Thomas Wayne, one fateful night Harley discovered the Wayne’s would be at a theater and convinced the reluctant Jack to finally help her take Thomas and Martha out. Not because she couldn’t do it by herself but felt this inner fear in Jack had to be defeated. Thomas and Martha were shot by Jack to Harley's extreme delight.

In the years hat followed, Harley and Joker caused chaos and fear wherever they went, more and more fueling Harley’s desire for power. Harley self appointed herself Queen Of The City as her ego had grown to consume her.