JOKER: FOLIE À DEUX (in OmdU)

At the end of the first “Joker” film, Arthur Fleck (Joaquin Phoenix) ends up in the so-called Arkham Asylum, the mental institution in Gotham City. There he meets the psychiatrist Harleen Quinzel (Lady Gaga). Through this encounter and the Joker's influence, she eventually becomes Harley Quinn.