The universe of Todd Phillips’ Joker will continue to be explored in a sequel, titled Joker: Folie à Deux, and though plot details continue to be a secret, there are already a couple of theories on what will happen now in the chaotic life of Arthur Fleck (Joaquin Phoenix). Back in 2019, Warner Bros. and DC explored a different version of Batman’s most famous villain in a completely different universe in Joker. Instead of focusing on Bruce Wayne/Batman and introducing the Clown Prince of Crime through him, Joker was all about the story of Arthur Fleck, a failed stand-up comedian dealing with mental illness who is pushed to his limits by the decay in Gotham City and some shocking reveals in his personal life.

That, among other factors, led to Arthur taking a much more violent and vindictive path that culminated with him becoming the leader of a violent countercultural revolution against the rich in Gotham, and thanks to his stand-up comedy efforts and the clown makeup he wore during his shocking TV appearance at the end of Joker, led to him being labeled as such. Joker: Folie à Deux will catch up with Arthur in Arkham State Hospital, where he was last seen at the end of the first movie and where he will meet Dr. Harleen Quinzel/Harley Quinn (Lady Gaga). Joker 2 will also be a musical, which along with the events of the first movie, Arthur’s condition, and Harley’s appearance, has led to various theories on what the movie will be about, and here are some of them.

10 Joker 2 Is A Musical Because Of Harley Quinn

Lady Gaga staring into the camera as Harley Quinn in Joker 2

There’s a lot of expectation around Joker: Folie à Deux not only because of how the first movie ended, but because the sequel will also be a musical. This has made way for a theory on why Joker 2 will have musical elements, and it’s all because of Harley. The theory is based on the narrative structure of Joker and how Arthur Fleck is an unreliable narrator, so this time, Arthur won’t be the lead of the story, and instead, it will be Harley Quinn. Through this, Joker 2 would help confirm what was real in the first movie and what wasn’t, but it would also justify the movie being a musical, as what the audience is watching is Harley’s fantasy. Arthur and Harley are two troubled minds, but they see the world very differently, and the way Harley lives the fantasies in her head and the way she deals with her reality could be through a musical.

9 Harley Quinn Is A Product Of Arthur Fleck’s Mind

Lady Gaga and Joaquin Phoenix as Harley Quinn and Arthur Fleck in Joker 2

Lady Gaga is playing Dr. Harleen Quinzel, a psychiatrist who falls in love with Arthur Fleck, just like she did with the Joker in Batman: The Animated Series, but Joker 2 might give this story a twist to fit with what the first movie established about Arthur. A theory shared on Reddit suggests that Dr. Quinzel will have a normal and healthy doctor/patient relationship with Arthur, but he will romanticize it to the point where he creates the idea of Harley Quinn, a woman with a troubled mind who follows him around and supports everything he does. The musical aspect would be part of Arthur’s fantasies of Harley, giving the audience a way to identify what’s real and what’s not. The theory fits even more as, in Joker, it was revealed that Arthur’s relationship with his neighbor, Sophie, was just in his head.

8 Joker 2 Will Introduce Batman (Thanks To A Time Jump)

Joker young Bruce Wayne

Among the biggest questions about the universe of Joker is if Arthur Fleck will ever face Batman. Joker introduced a young Bruce Wayne, whose parents were killed during the riots that Arthur’s actions in Murray Franklin’s show unleashed all over Gotham, thus setting up his eventual transformation into Batman. However, as Arthur is a lot older than Bruce Wayne, a theory shared on Reddit suggests Joker 2 could have a time jump, so it can see an older Bruce Wayne starting his journey as Batman. This would be possible as Arthur is now locked up in Arkham, so he could spend many, many years there while Bruce trains and becomes Batman, meaning he will be ready to face his biggest enemy from the comic books.

7 Joker 2 Will Give Arthur Fleck A New Origin Story

Joaquin Phoenix as Arthur Fleck the Joker

As mentioned above, Arthur Fleck is an unreliable narrator, which made way for many questions about which parts of Joker were real and which were in Arthur’s head, and that’s the basis of the next theory. Also posted on Reddit, the author of this theory suggests Joker 2 will be another origin story for the title character. Now that Arthur is in Arkham, his mind could come up with a different origin story and present a new series of events that, according to him, led to his transformation into the Joker, which fits with how the character’s backstory has been in constant change in the comic books.

6 Joker 2 Will See The Rise Of A New Joker

Split image of Joaquin Phoenix as Arthur Fleck in and out of Joker makeup.

One of the most popular theories about Joker was that Arthur isn’t the real Joker, and the sequel would introduce the real one, and another theory took this idea and gave it a twist. A Reddit user suggests that, as Joker 2 will deal with the consequences of the riots and chaos that Arthur unleashed at the end of Joker, this will lead to the rise of a new Joker, inspired by Arthur’s actions. This would follow the line of Arthur having very bad luck, so much so that someone smarter will take his place and the credit for everything he started. This theory would also make it possible for this universe’s Bruce Wayne to face the Joker in the future, as the new one would be younger than Arthur and thus a more fitting villain for this version of Batman.

5 Arthur Fleck Will Face Another Joker

Barry Keoghan as Joker in The Batman and Joaquin Phoenix as Arthur Fleck in Joker

Another theory explains that, instead of another Joker taking over at the end of Joker 2 because Arthur Fleck dies, is too mentally damaged, or it’s just his bad luck, there will be a second Joker creating chaos in Gotham and facing Arthur (and Harley Quinn). At the end of Joker, Arthur already had a lot of followers, and set photos from Joker 2 showed people wearing clown masks in support of Arthur, so one of them could take the lead and become more popular than Arthur, who will be “consumed with envy”. The author of the theory adds that the new Joker could make fun of Arthur just like everyone else did in the first movie, making his life tragic again and possibly driving him to an even more tragic fate, one that he considered in the first movie. Arthur dying as a result of this would make the new Joker truly evil in the eyes of the viewer, and it fits the “folie à deux” title perfectly.

4 Arthur (& Harley) Will Free Arkham’s Patients In Joker 2

A split image of Arthur Fleck being shaved in Joker 2, and Fleck at the end of the first Joker is Arkham

With Arthur and Harley in Arkham, this institution will not only be one of the main settings of Joker 2, but it might also see its end. Videos from the set of Joker 2 showed Arkham on fire, which made way for a theory that says Arthur and Harley will rally the patients against the doctors and nurses in Arkham and they will escape, but not before setting the place on fire. The author of the theory suggests the 1975 movie One Flew Over the Cuckoo’s Nest will be the inspiration for Joker 2 and Arthur and Harley’s actions against Arkham, which doesn’t sound too crazy as the first movie took a lot of inspiration from Martin Scorsese’s The King of Comedy, so it wouldn’t be surprising of Joker 2 is also heavily inspired by another movie.

3 Joker 2 Will Introduce Arthur & Harley’s Son

Arthur Fleck and his Joker persona

The title “folie à deux” has made way for many interpretations, including one that suggests Joker 2 could introduce the son of the Joker. However, and based on what’s known so far about the story, it’s unlikely that Joker 2 will center around Arthur’s son, but it can definitely set that storyline up. Joker 2 could end with Harley Quinn learning she’s pregnant with Arthur’s child, setting up a third movie that will properly introduce their son and explore his complex relationship with his parents, as in the comics, Joker Jr. grows up to resent his mother and follows his father’s steps – and this could make him the Joker that this universe’s Bruce Wayne will face in the future.

2 Joker 2 Will Introduce Jim Gordon

Jim Gordon in a DC Batman comic

Joker 2 will introduce new characters aside from Harley Quinn, and one of them will be played by Brendan Gleeson, though who this character is remains unknown. A theory suggests Gleeson is playing Jim Gordon, and he will be brought to help the Gotham City Police Department hunt Arthur and Harley down as they unleash chaos all over Gotham City. In addition to that, Joker was about how the failures of American mental healthcare, and with Jim Gordon in Joker 2, the sequel could now focus on the justice system in Gotham and its failures – after all, there’s a reason why Gotham is plagued with crime and has seen a variety of villains.

1 Joker 2 Will Be About A Multiverse

Two images of Arthur Fleck as the Joker.

Another popular though unlikely theory is that Joker 2 will be the beginning of a multiverse of Jokers. A video from the set of Joker 2 shows Arthur Fleck being chased by two other Jokers, which has made the audience wonder if this is one of Arthur’s delusions or if it’s real, and in that case, if Joker 2 could see a multiverse. The superhero genre, both on Marvel and DC, is currently focusing on multiverses, so Joker 2 could be the beginning of a very specific type of multiverse, one that some viewers are suggesting could see a crossover of Jokers with cameos by Jared Leto and even Jack Nicholson. As previously mentioned, this theory seems unlikely, especially the suggested cameos, but Joker: Folie à Deux could surprise the audience in more than one way.

Key Release Dates