Who is the Joker? Ever since being introduced in the comics as Batman’s first and foremost foe in 1940, this question has never truly been answered. Joker’s backstory is forever foggy, multiple stories from a cackling unreliable narrator, the truth left to fizz in a vat of acid. Todd Phillips’ darkly beautiful 2019 standalone spin-off movie Joker offered an unexpected new backstory for the supervillain, heavily inspired by Alan Moore’s Batman: The Killing Joke and Martin Scorsese’s The King Of Comedy: introducing us to Arthur Fleck (Joaquin Phoenix), a sad clown abandoned by a cruel world, taking on the Joker mantle almost out of sheer desperation.

So, who is Arthur Fleck now? The amusingly Nouvelle Vague-esque title Folie À Deux alludes to a burgeoning romance, but also his fragmenting identity crisis. Central to this new film is a question of self: is the Joker simply a delusional character living inside him,...