Joker: Folie a Deux introduced the classic Batman character Harvey Dent, but some very notable changes to him. DCs Joker: Folie Deux, the sequel to the groundbreaking 2019 film Joker, brings a new layer of complexity to the story of Gotham City and its iconic characters. Continuing its explorations of themes like mental illness and societal decay, Joker: Folie a Deux incorporates classic DC characters, reimagined for Arthur Flecks grim vision of Gotham.