The origin of the Joker and Harley Quinn’s toxic relationship was altered for the New 52, DC’s 2011 revamp of its entire line. The changes were subtle on the surface, but for many Harley Quinn fans, the New 52 version of the character was totally different at the core. In Paul Dini and Bruce Timm’s seminal one-shot The Batman Adventures: Mad Love, Harleen Quinzel falls in love with the Joker during their therapy sessions and, even though she was heavily influenced by the Joker, she joins his ranks willingly. That’s not the case in the New 52.
In the updated origin story, the Joker pushes Quinzel into a vat full of the same chemical that bleached his skin white and turned him insane, and he does so against her will. For many, this fundamentally changed who Harley Quinn was as a character, altering her agency and the whole nature of her relationship with the Joker. “This made Harley appear as more of an unwilling victim than she had ever appeared before,” one Outer Places piece on Quinn’s origins claims. “In the New 52, she became a sociopathic, psychotic monster not totally by choice, but at least partially because of the Joker’s cruelty.”
David Ayer’s Suicide Squad featured a mix of both origins, with Margot Robbie’s Quinzel taking an oath to the Joker and jumping into the vat herself. The actress has gone on the record multiple times since then, saying she majorly regrets doing the scene because of how disgusting all that slime was.