I'm immediately torn on Joker getting a sequel. Despite all of the meme culture around it and the massive misunderstandings of who and what the film represented, I loved the movie, especially Joaquin Phoenix's Oscar winning portrayal. In a world of constant interconnected universes, it was interesting to see such an iconic comic book character explored in a fresh, grounded way in a standalone story. A sequel doesn't mean the start of the JCU, and will likely remain focused on Joker and his further descent (or would that be ascent?) into madness, but the title gives us a few hints.
Joker: Folie a Deux is the name of Joker 2 and, as all Fall Out Boy fans will know, Folie a Deux means 'madness shared'. There are a number of different interpretations of this on offer. The finale of Joker sees him become a deified figure in the community, as the downtrodden embrace his reckless violence and begin an uprising against the capitalist systems that keep us all underfoot. It represents the ways in which desperate societies can be corrupted by a cult-like figure who allows them to give into their basest instincts, but of course our poor media literacy means a common take away from Joker is that life sucks for men, specifically.
Director Todd Phillips will be acutely aware of how Joker has been embraced by the exact sort of viewers who were supposed to learn from it, and the 'madness shared' could be more metaphorical, with the movie addressing and focussing on those who unironically saw Joker as a hero character, sticking it to The Man (or The Person In Power Of Unspecified Gender, thanks Woke Police) in this era of MeToo, cancel culture, and Johnny Depp memes. The madness shared might be with us.
The most obvious choice for a regular Joker story would be Batman, but given that Bruce Wayne is a child in the first movie and bringing in Batman is just about the worst choice this series could make, it's unlikely that will happen here. Thankfully. A teenage Batman struggling to deal with his own privilege in a society run amok while Joker becomes an increasingly destructive menace? That's a decent idea, but just a fist fight with Bat Knuckles? Pass.
One of the things I haven't seen mentioned at all is a theory that I think is more likely than it's being given credit for. Who truly shares the Joker's madness, like no one else does? Harley Quinn. We are firmly in the middle of the Quinnaisance right now, with Kaley Cuoco's animated version riding the coattails of Margot Robbie's live action version, who herself is standing on the shoulders of the voice work previously done by Arleen Sorkin and Tara Strong. Harley is one of the most popular characters around right now, and Todd Phillips' version would be fascinating to see. Much like Phoenix's Joker keeps the core violence, tragicomedy, and derangement of the typical portrayal, there are elements of Harleen you could airlift out and paint her in a grungier light. Rooney Mara, Phoenix's real life wife, would be stellar casting if the movie goes in this direction.
Of course, it could also mean none of these things. Despite its title and the famous stair sequence, we don't really see Joker be the Joker here. He's just Arthur Fleck, and things get a little out of hand. He's a supercharged Bernie Geotz, hero and villain, saviour and force of aimless vengeance. Joker is 'you don't look so bad, here's another' wrought flesh. It's only those last 15 minutes where we see him embrace the title role, and the sequel could see an evolution of that. The madness isn't shared with anybody, it's simply split between Arthur and Joker. It'll likely be over a year before we hear any more from the movie at all, but that won't stop be starting the #RooneyMaraForHarley campaign now.