Harley Quinn, whose real name is Harleen Quinzel, is The Joker's devoted lover. A former high-level gymnast, she earned a university scholarship, then studied psychiatry before landing a job at Arkham Asylum where she meets The Joker. Fascinated by him from the first moment, Harley is seduced by his stories of past traumas, which turn out to be false but push her to fall madly in love with him. Blinded by this love, she becomes incapable of seeing the reality of the psychopath that The Joker is.
Harley adopts a harlequin costume in homage to the nickname The Joker gave her and helps him escape from Arkham. Thus begins her criminal career, marked by a fascination with pranks and a circus character appearance, accompanied by two hyenas as pets.
The relationship between The Joker and Harley Quinn is a striking example of toxicity. The Joker abuses Harley both physically and psychologically and even tries to kill her. Despite this, Harley remains unaware of this manipulation, content with the rare gestures of affection he shows her.
In the comics, the relationship between The Joker and Harley Quinn reaches heights of toxicity and darkness never shown on screen. In The Joker: Death of the Family, written by Scott Snyder, The Joker kidnaps Harley and threatens to mutilate her face to reflect his image. He plays on her fears, making her believe he has committed the atrocious act, while he has only put a red hood on her.
Harley, blinded by obsessive love, idealizes The Joker and their relationship, losing all lucidity. The Joker maintains this illusion with small demonstrations of tenderness, ensuring her loyalty. This dynamic creates a deep insecurity in Harley, exploited by Batman on several occasions to manipulate her.
With the release of Suicide Squad in 2016, the characters of The Joker and Harley Quinn gained new popularity. The Joker, played by Jared Leto, and Harley Quinn, played by Margot Robbie, brought modernity and new dynamics to these characters.
However, the film does not delve deeply enough into the complex relationship between The Joker and Harley. We see a Joker showing more compassion, although still cruel. The character of The Joker takes a backseat, while Harley Quinn better reflects his essence of madness and desperate love for The Joker, while aspiring to a normal life.