Harleen Quinzel was once an innocent girl that, upon graduating from Gotham University, she became infatuated with the criminals inhabiting Arkham Asylum. When she worked there as a psychiatrist, she was chosen to be the therapist for The Joker, where she was unwillingly manipulated into working beside him. Harleen helped escape from Arkham, thus dressing up as a harlequin simply named Harley Quinn. However, as Harley would fall into a relationship with Joker, it became unrequited, as the latter had a rather warped understanding of love, and sometimes even manipulated her further to keep her in the game, essentially using her as a sort of whipping toy. After Joker's first death after Arkham City, Harley was so distraught that she attempted revenge on Batman and Robin, but soon reunited with her "puddin'" after finding him alive some months later. Between these adventures, Harley would eventually end up joining the elite Suicide Squad.

After Superman killed the Joker in the Injustice universe, however, Harley started the Joker Clan, who worship him as a martyr. Her and the Joker clan carry out acts that distract and annoy the One Earth regime, earning the trust of the Insurgency.

The basis of the voice should emulate Tara Strong's performances as Quinn since Arkham City. However, for the Primeverse version, you may also emulate a little bit of Margot Robbie's performances in the two or three lines she has.