The Joker sequel is officially coming, titled Joker: Folie à Deux. However, along with the news of the sequel came little news about what the movie would include, making it difficult to pin down what elements of the comics may be adapted. Fans do know that Lady Gaga is in talks to join the cast as possibly Harley Quinn (per the Hollywood Reporter), and it will also be a musical.
With all that information, there are some places that the franchise could go to find its story, even if just as far as influences for what happens. Joker has been around longer than any other Batman villain, and there are a lot of directions to go, but with Harley Quinn possibly involved and the title offering its own clues, it is a little easier to narrow it down to a few key stories over the character's existence.
Joker
Brian Azzarello And Lee Bermejo delivered a frightening Joker to DC in an alternate take on the Batman villain. Since the first movie showed it took place outside the DCEU timeline in a world that clearly didn't have superheroes, this could be a great outside-the-box story for the sequel.
Joker sees the villain released from Arkham Asylum and immediately deciding to take over as Gotham City's crime lord. What makes this story interesting is that the tale is from the point of view of one of his henchmen, which could go a long way to keep the Joker sequel from repeating the first movie's reliance on Fleck's unreliable perspective.
Batman: Harley Quinn
Longtime fans know that Harley Quinn existed in the animated cartoon, Batman: The Animated Series before she ever showed up in comics. Harley was so popular that she made her move to comics, and in this one-shot issue by co-creator Paul Dini, her origin was told.
This showed how Harleen Quinzel met Poison Ivy as well as how she fell into the spell of Joker and became Harley Quinn. It also showed Joker realizing he was falling in love, so he decided he wanted to kill her. The dynamic in this story was the one that existed for years between the two and could be a great introduction in the new Joker movie.
Mightier Than The Sword
In the story Mightier Than the Sword, Harley Quinn got out of Arkham Asylum and decided she could make some money by writing a memoir, in which she reveals everything she and Joker did together. Needless to say, this was not something Joker wanted the world to know, and he set out to stop her.
The new Joker movie is a musical. If it has a bookend of a similar story, where Harley decides to reveal everything she knows about Joker to the world, those stories playing out in bizarre song numbers could be incredible.
A Serious House On Serious Earth
The first Joker movie proved that the Clown Prince of Crime could exist in a world where Batman does not exist yet. In the movie, Bruce Wayne was still a child and Thomas Wayne was still alive. That could open the chance to use Batman comic books as a template without really needing to add Batman himself to the mix.
In A Serious House on Serious Earth, Batman enters Arkham Asylum during a riot led by Joker. While there is no way to do this as a straight adaptation since Batman does not exist yet, there is always a way to do it with just Joker, and it could open up the world to any number of future Batman villains already in the institution.
The Return Of The Joker
The title of the new movie is Joker: Folie à Deux, which makes it sound like there could be more than one villainous lead. This could be Harley Quinn, but there is also a chance it could be a second Joker. In the story "The Return of the Joker," a series of murders build up by a fake Joker.
While the comic has Batman and Commissioner Gordon seeking out the villain, with little luck, it is Joker who comes back to stop him. In this story, Joker returns to his original persona of Red Hood to seek the killer out and stop him while also dealing with his own insecurities.
Harleen
Harleen is more of a Harley Quinn story than a Joker one, but it still has Joker at its center and could be the perfect story featuring the duo that Joker 2 could adapt. This is a reimagining of Harley's origin story, where she goes from being a brilliant psychiatrist to Joker's sidekick and fellow villain.
The story would also fit well with the original Joker movie, as it shows the change from within Harley's own mind as she begins to fantasize about Joker while suffering nightmares about her life. Despite warnings from everyone around her, Joker inspires Harley to become the character fans know today.
Soft Targets
Soft Targets would be a great Joker story to adapt for the sequel because it can play out without using Batman at all. In this story, Joker finally goes off the deep end and starts killing people in a much more realistic way than he usually does. He uses a sniper rifle, and he is only doing this because he wants to spread fear across Gotham City.
This might be a tough story to adapt in today's world thanks to real-world issues, but it showed how Joker wanted to hurt people and make everyone fear him while sending the GCPD Major Crimes Unit scrambling to figure out his next targets and stop him.
Three Jokers
The biggest question throughout the first Joker movie was whether Arthur Fleck was really The Joker. Much of what happened in the movie was in his head, and it was clear that the unreliable narrator made it impossible to determine what was real in the movie. This includes whether Fleck really was Joker.
In Three Jokers, it turned out that there wasn't one real Joker, there were three. There was the criminal, the comedian, and the clown. Fleck is the comedian, based on the first movie, and if the second movie has Harley Quinn pulling the truth out of Fleck, the idea of more than one Joker could be an interesting path to explore.
The Killing Joke
The first Joker movie was clearly influenced by The Killing Joke, but there is so much more to this story that could play into the world of the Joker movies. For one thing, Joker was never really the villain that DC fans knew in the first movie as that was just the road to his loss of control.
The second movie could continue that, especially if he has someone like Harley Quinn helping him. Having Joker set out to make life miserable for those he feels wronged him could lead to him finally taking the role of the true Clown Prince of Crime.
Mad Love
Just like the first Joker movie played around with the origin story in The Killing Joke, the second movie could easily pull a lot from the famed Mad Love storyline, easily the most popular of all the Joker and Harley Quinn stories.
This comic was set in the Batman: The Animated Series universe and showed Harley's origin story as she goes from a teenage gymnast to a psychiatrist infatuated with Joker. The story has her obsession with Joker and his disregard for Harley until she makes the mistake of trying to kill Batman. There is a lot about this story to bring to a Harley Quinn movie involving the Joker.