Harleen Quinzel was a bright energetic young girl who won a gymnastics scholarship to Gotham State University. Her goal was to get a psychology degree and become a famous pop psychologist and become wealthy with a line of self-help therapy books. Unfortunately, life doesn't always go as planned, and you have to play the cards that you are dealt. She didn't have the determination to study, always preferring the easy way out, but would do anything it took to get her grades upped. With this, she earned the highest grade marks be returning sexual favors to her college professors.

She requested to intern at Arkham Asylum, finding that extreme personalities were more interesting, challenging and high-profile. She was captivated by the Joker at first sight. He quickly took advantage of her, pouring his sad troubled soul out to her. She pitied him and saw him making desperate cries for help. Once when he escaped, she worried about him, alone and confused in the real world, until he was returned, battered by Batman. She immediately went to a costume store and returned to rescue Joker as Harley Quinn. She desperately loves him, and takes the angry abuse that he dishes out. But she is faithfully at the Joker's side, as his self-appointed main squeeze.