In the DC Extended Universe film Suicide Squad, flashbacks show Joker convinced Harley Quinn to bath in the same chemicals as he did. After their break up, a drunken Harley blew up Ace in Birds of Prey.
The DC Extended Universe film Suicide Squad showcases flashbacks where Joker manipulates Harley Quinn into bathing in the chemicals he used. After they went their separate ways, a tipsy Harley recklessly blew up Ace in Birds of Prey.