Joker 2 twist ending was teased by Joaquin Phoenix's director Todd Phillips five years ago

Five years on from the Oscar-winning $1 billion success of and Joaquin Phoenix returns alongside director Todd Phillips for the sequel.

Joker Folie à Deux sees Arthur Fleck in Arkham Asylum after killing Robert De Niro's TV host live on air in the first movie.

Joker 2 follows his murder trial, with prosecution attorney Harvey Dent (the future Batman villain Two-Face whose facial scarring we witness later in the movie) seeking the death penalty.

At the end of the movie, Arthur is back in Arkham where he's approached by Connor Storrie's Young Inmate (check out his Instagram below), who is seen smirking and leaning on a wall earlier in the movie.

Just as Arthur did with Murray Franklin in the first movie, he tells him a joke before taking his life.

The Young Inmate stabs Arthur multiple times in the stomach as Phoenix's character falls to the ground bleeding to death. Off-focused in the back, Storrie's prisoner cackles as he carves a Glasgow smile into his own face. This implies that he is the real Joker who will take on the Batman that the young Bruce Wayne in the first Joker movie will grow up to become.

As for his motive, he was probably a fan of Arthur who felt betrayed after he denounced his Joker identity, so kills him and takes the mantle on himself with an irreversible physical scarring. But did you know that the director teased this twist ending five years ago upon the original film's release?

Following Joker's Golden Globe nominations, : "There's many ways to look at the movie. He might not be Joker. This is just a version of a Joker origin. It's just the version this guy is telling in this room at a mental institution. I don't know that he's the most reliable narrator in the world, you know what I'm saying?" Interestingly this twist has occurred before in lore, with a last minute Joker switch twist at the end of the Gotham TV series.

The director also told this week: "One of the things that people never understood about the first movie was, 'I don't get it. He visits Bruce Wayne and he's 30 years older than Bruce Wayne. What kind of geriatric Joker is going to fight in the future?' I don't know if you've ever saw the script of the first movie. The first film is called Joker. It's not called The Joker, it's called Joker. And the first film under the script always said 'An origin story.' Never said THE origin story. It was this idea that maybe this isn't THE Joker. Maybe this is the inspiration for the Joker. So, in essence at the end of this movie, the thing you're being left with is 'Wait, what is that thing happening behind him? Is that the guy?'"

Joker Folie à Deux is in cinemas now.