There are major spoilers in this article for Doctor Strange in the Multiverse of Madness.

Since its parent company Disney acquired Fox in 2019, the biggest question surrounding Marvel has been about when it will expand its universe. More specifically, fans have been wondering: When will the company crack open its war chest and let the X-Men and Fantastic Four into the Marvel Cinematic Universe?

Doctor Strange in the Multiverse of Madness, Marvel’s latest release, provided the closest and clearest answer yet.

Countless crossovers have happened and continue to happen in the comic books, but because of Marvel’s bankruptcy in the ’90s, financial deals were made that split Marvel’s superheroes’ film rights among different studios. Those deals eliminated the potential of crossover movies. Disney’s Fox acquisition was the first step in getting Marvel’s heroes under one umbrella. With the introduction of the multiverse, the possibilities are endless.

In the latest Marvel film, Doctor Strange rockets through the multiverse, entering alternate dimensions, and he finds himself in a world where a powerful group of superheroes have formed a council called The Illuminati. That group includes Reed Richards, leader of the Fantastic Four (played for the first time by actor John Krasinski) and Professor Charles Xavier, the head of the X-Men (Patrick Stewart reprises the role). They’re joined by alternate universe MCU characters, including Doctor Strange’s own nemesis Karl Mordo (Chiwetel Ejiofor). It’s one of the splashiest moments of the movie because it signals a world where all of Marvel’s iconic characters exist within the same cinematic (if not actual) universe!

Unfortunately though, they both die within 10 minutes of their appearances. It’s a rather short-lived reunion.

Still, thanks to the multiverse, their demise does not mean that these characters are dead forever. It’s complicated, and features a couple of big caveats, but here’s how those heroes could come back, how Marvel opened the door with this giant tease, and what ultimately stands between fans watching their favorite heroes all zip around in one super-sized movie.

The Multiverse means infinite versions of every hero

In the Multiverse of Madness, Doctor Strange (Benedict Cumberbatch) and America Chavez (Xochitl Gomez) travel through universes and find themselves on Earth 838 — a place that feels a lot like Strange’s home planet of 616 (the main MCU universe) but with some odd tweaks. Those differences include opposite logic traffic signs, sphere-shaped pizza, and a New York City where lush vegetation grows up on the sides of buildings. But the most significant divergence between 838 and 616 is who’s a superhero and who isn’t.

In 838, familiar faces Maria Rambeau (Lashana Lynch) and Peggy Carter (Hayley Atwell) are heroes, the latter being a callback to Marvel’s animated Disney+ show What If. The 838 universe also features mutant telepath Professor Charles Xavier and cosmically-altered genius Reed Richards, both of whom are major comic book characters and appeared in Fox’s Marvel movies (Richards was previously played by Ioan Gruffudd and Miles Teller). Mordo and Black Bolt (Anson Mount), the leader of the superhuman race called in the Inhumans, and star of the very awful television show that Marvel would like us all to forget, are also present in 838. The Illuminati is a concept that’s adapted from the comic books.

Marvel Comics

While I’m sure these characters had full lives in their universe, they didn’t stick around for very long in Multiverse of Madness. They fail to take 616 Doctor Strange’s warning about Wanda seriously and she — through a spell that allows her to possess a version of herself in that universe — obliterates each hero in creatively horrifying ways.

Yikes! But they’re not dead-dead.

The MCU’s multiverse rules are that when each parallel universe is created, that universe then has its independent timeline (in the Disney+ series Loki, the Time Variance Authority would eliminate parallel universes based on specific, significant events that occur in the main, “sacred” timeline). These independent universes mean then that if someone dies in one universe, it doesn’t necessarily mean that all their multiversal selves will meet that same fate in the same way — an example is the difference between the late Doctor Strange in 838 (also Cumberbatch) and the very alive and kicking Doctor Strange from 616.

So while the 838 heroes were exploded, spaghetti shredded, bisected, crushed, and had their necks snapped, there’s still a possibility that their alternate versions are faring much better. And if alternate Reed Richards, Professor X, and Black Bolt exist in the 616 it could signal the introduction of those heroes and their respective superhero teams to the MCU!

But there’s one big catch

Before we get too excited by the prospect of these heroes popping up in the MCU, there’s a big storytelling caveat that stands in the way: There’s no guarantee that the aforementioned 838 heroes are superhumans in the 616 universe. Because each universe is unique and major events occurring in those universes are distinct, the circumstances that turned Reed Richards, Professor X, and Black Bolt into super-powered individuals might have never happened in 616. They could be just regular people.

The pertinent examples of this are Captain Carter and Maria “Captain Marvel” Rambeau who share chairs on the Illuminati with the aforementioned super dudes. As we’ve seen in previous Marvel properties, their 616 counterparts never became super were just normal humans living alongside their friends Steve Rogers (Chris Evans) and Carol Danvers (Brie Larson).

Marvel

What’s significant about Captain Carter/Captain America and the Captains Marvel origin stories is that their superhuman nature wasn’t something they were born with. In both universes, those heroes made a choice or performed a certain act, and were granted superpowers as a result of that decisive moment. This figures in with Reed Richards who, according to his comic book origin story, was bombarded with cosmic rays after he and his family venture into space. If that trip to space is altered in 616, then ostensibly 616 Reed could just be a regular guy. That said, Marvel has a Fantastic Four movie in the works, but as of yet no release date and no director.

What’s a little more unclear are the backstories of 616 Professor X and Black Bolt who, in the comics, have superpowers linked to their mutant and Inhuman DNA. Multiverse of Madness is the first time that Marvel Studios has directly referenced both characters in a movie, and Marvel hasn’t yet established mutants or Inhumans on the big screen (Black Bolt and the Inhumans were introduced in their own, universally panned 2017 tv show). Including those heroes in the MCU would be a big step for Marvel since it involves opening a can of narrative worms. It means having to explain not only who these characters are, but also the background of mutants and Inhumans, how they came to be, and how they could be present in the MCU for so long without Fury or S.H.I.E.L.D. knowing they exist.

Marvel is sort of in an odd storytelling corner because of how popular the X-Men, and to some extent the Inhumans, are. The X-Men not only have been A-list comic book characters (and are currently in the middle of a resurgence) but also have starred in two lucrative cinematic trilogies. Casual fans know their basic history, their superpowers, major characters’ arcs, and the iconic actors like Stewart who played those characters. With the X-Men, it’s not that Marvel has to reinvent the wheel, but that they need to make that wheel fit seamlessly into the MCU’s grand design.

… Oh wait, there’s one more big catch

For the most part, Marvel has mostly depicted multiversal travel as a one-way street. Characters from the 616 go to other multiverses or timelines. But if we think of the multiverse as a two-way street, then Marvel heroes from other universes could possibly hop into 616 Earth just as Strange and America blasted themselves into 838.

Rarely have there been other dimension dwellers hopping into 616. In Endgame, past 616 versions of Nebula, Gamora, Thanos, and his army make the jump to present-day 616 through time travel. They aren’t different versions of those characters though — they’re the same characters, just time-displaced.

Even America Chavez, who can travel the multiverse at will, is more or less depicted as a 616 mainstay because she spends most of her time traveling with 616 Strange. Their adventure is from Strange’s point of view.

But the Multiverse of Madness and its mid-credits scene hint that though we don’t see dimension skippers crashing into 616, it doesn’t mean that it’s not happening elsewhere. Reed Richards and the Illuminati explain that multiversal travel has happened in the past and caused incursions — the Marvel term for a universe collapsing itself. The takeaway is that it’s possible to “travel” the multiverse through the use of magic spells or some way other than America’s power, but doing so risks the universe imploding.

Courtesy of Marvel Studios

And in that credits scene, Clea (Charlize Theron) tells Strange that she needs his help because there’s an imminent incursion happening in another universe. Clea herself can seemingly travel through the multiverse through what appears to be the dark dimension (but again, this is a credits scene and there’s a lack of information surrounding Clea and the extent of her powers at the moment).

Multiverse jumping could also be an easy narrative device to get around the massive chronological and source material knots in existing characters’ origin stories. Theoretically, it gives Marvel the flexibility to cast different actors too while, say, still paying homage to Stewart’s legacy. A story could feature a younger Professor X and some of his X-Men from a different universe (but with the same comic history) traveling to 616 and boom, they’re in the MCU.

There’s a precedent in Marvel’s comic books. Marvel’s 2015 crossover event Secret Wars included a major storyline in which the main alternate universe (Earth-1610) and others were destroyed. Ultimately, the concluding events of Secret Wars brought 1610’s Miles Morales into the main comic book universe with Peter Parker, the existing Spider-Man.

It’s not hard to see an MCU future where this plot device could be used to do something similar.

That said, with all these loops and twists, the most powerful determining factor in when we’ll see iconic Marvel characters and Black Bolt enter the MCU is Marvel’s already-packed movie release schedule. The company has Thor: Love and Thunder (July 2022), Black Panther: Wakanda Forever (November 2022), Ant-Man and The Wasp: Quantumania (2023), Guardians of the Galaxy Vol. 3 (2023), the Carol Danvers-focused sequel The Marvels (2023) on the way. It also has a Blade reboot and the aforementioned F4 movie with yet to be determined release dates. This is in addition to a slew of upcoming series on Disney+ that include Ms. Marvel and She-Hulk.

Squeezing an X-Men movie into that assembly line would require shuffling sequels around.

So while the door is open for Marvel to finally bring in its beloved characters, it could conceivably take until late 2024 or 2025 before we fully see the X-Men or the Fantastic Four in the MCU. Marvel fans would surely like to see them enter the fray much sooner — and hopefully for much longer than they managed to stick around in the Multiverse of Madness.