In Todd Phillips’ sequel to Joker, Joker: Folie à Deux, Arthur Fleck (Joaquin Phoenix) is imprisoned at Arkham Asylum, awaiting trial. His lawyer, Maryanne Stewart (the always reliable Catherine Keener), is trying to get him moved to a better hospital where he can be treated. After his on-air murder of Robert De Niro’s Murray Franklin in the first film, Fleck is a celebrity among the inmates and even the guards. The lead officer in charge of him, Jackie Sullivan (Brendan Gleeson), asks him every day to tell a new joke. He is taking meds and seems to have achieved a sort of depressive equilibrium. It looks like his lawyer may have a shot at getting him declared unfit for trial or convincing a jury that Joker is a separate dark personality brought on by childhood trauma.

“…Lee embraces the idea of being beside Fleck as he sets the city on fire, and she expects him to take up the mantle of the ‘Clown Prince of Crime.’”
The furor over the Joker has gripped Gotham. An entire layer of society, feeling left out of the economy and living on the low end, has anointed him as their messiah and rallying point, cheering him for violently speaking truth to power. This is more of a “social justice” purpose than Fleck put into his actions, but he revels in the attention. For the first time in his life, he is seen and valued, even if he doesn’t always understand or care about the underlying drivers of that fame.
Stewart is steering the situation toward the best outcome for Fleck, and this goes well until he meets Lee Quinzel (Lady Gaga) in a vocal music class at Arkham. She gives him attention he’s never had from a woman, and she begins to pull him away from his lawyer’s plan. Lee embraces the idea of being beside Fleck as he sets the city on fire, and she expects him to take up the mantle of the “Clown Prince of Crime.” This is opposite the comics, of course, where Joker leads Harley astray. Given that Fleck deluded himself in the first film into fabricating a whole relationship with his neighbor Sophie Dumond (Zazie Beetz), it’s fair to ask how real Lee is… and we find out early on. To say more would be to give it all away.