The 'Avengers: Endgame' moment that could introduce the X-Men to the MCU (spoilers)

The Marvel Cinematic Universe (MCU) as we know it is over. The 22-film run that began in 2008 with Iron Man and The Incredible Hulk has been brought to a satisfying conclusion in Avengers: Endgame, with very few loose story threads left dangling.

But this is Hollywood and, if we’ve learned anything from the MCU, it’s that the show must – and will – go on. Although we know very little about what to expect from Marvel Studios in Phase 4 (or even if Phases are a thing any more), one thing we know for certain is that the X-Men (including Deadpool) and the Fantastic Four are coming.

Disney acquired 20th Century Fox earlier this year, bringing the film rights to those two Marvel comic book franchises back home, ripe and ready to be exploited adapted. Marvel Studios mastermind Kevin Feige says it could be 4-5 years before we see the X-Men in the MCU, but we believe the seeds for their arrival have already been sewn.

Read more: Every MCU film coming after Endgame

After all, this is the franchise that teased Thanos for over a dozen films before finally bringing him in to play.

Endgame spoilers are incoming, so if you’re ready to throw yourself down a rabbit hole of theorising and speculation, throw on your tinfoil hat and carry on scrolling past the trailer below to find out how we think the X-Men will be introduced to the MCU.

The plot of Avengers: Endgame revolves around Captain America, Iron Man, Hulk, Thor et al trying to undo the decimation of the living universe wrought by Thanos at the end of 2018’s Avengers: Infinity War.

The remaining Avengers embark on an audacious mission to retrieve the six Infinity Stones from the past in a thrillingly staged Time Heist. This sets up a showdown with Thanos who arrives on Earth to face the Avengers, and prevent his grand plan from being undone.

The team has crafted a new Infinity Gauntlet and Hulk is chosen to don the glove and perform a new “snap” to bring the fallen back to life. And this is where, we think, the plot thickens.

The “snap” severely maimed Thanos in Infinity War, and so Hulk is deemed the only one strong enough to wield the new Infinity Gauntlet because of the Gamma Radiation “coursing through his veins”, that gives him his superpowers.

As we later learn, the “snap” has worked, restoring the fallen half of Earth’s (and the universe’s) population back to life, including Spider-Man, Doctor Strange, Black Panther, and the Guardians of the Galaxy.

Peter Parker later tells Tony Stark that the five years he spent as dust felt like they happened in an instant, so they weren’t sat waiting in the Soul Stone’s transdimensional waiting room, they were literally willed back to life by the Infinity Stones, with a little help from Hulk.

Now what if – and this is a big “what if” – not everyone brought back to life returned from the dust unchanged? What if the Gamma Radiation in Hulk somehow affected the DNA of some of the returning fallen?

Read more: What the ending of Endgame means for the MCU

What if Hulk inadvertently caused a mutation in a small but significant portion of the returned fallen, and what if those affected became mutants like we have in the X-Men world?

In the comics, mutants are humans that possess a genetic trait known as the X-gene. Those affected tend to manifest superhuman abilities at the age of puberty.

Bringing the X-Men into the MCU is fraught with difficulties anyway. At various points in the Marvel comics, the number of reported mutants – Homo Superior – ranges from around 10% of the global population (753m mutants) to 32m, down to just 198 after an event called “Decimation”.

In a neat piece of symmetry, the official name of Thanos’ “snap” in MCU canon is also “The Decimation”. Coincidence? We think not.

Introducing any numbers of mutants with superpowers poses the question of ‘why haven’t we seen them in the MCU before?’

X-Men: Dark Phoenix star James McAvoy pretty much said the same thing to Yahoo earlier this year when we spoke to him about the X-Men joining the Avengers on screen.

“I don’t know if the X-Men could go into the Marvel universe, I’m not sure,” said the Professor X actor.

“Maybe they could? But I think what’s different about the Avengers universe anyway is you’ve only got a couple of superheroes in the world. There’s a good amount, but there’s like a couple of football teams’ worth, you know what I mean?

“Whereas in the X-Men world you’re potentially saying there are hundreds of thousands, maybe millions of [superheroes] and the social implication of that is different.”

Scarlet Witch and Quicksilver, two characters borrowed from the X-Men world for Age of Ultron and beyond, could only ever be referred to as “enhanced” in the MCU as Fox had the stranglehold on the term “mutant”, so there’s no real precedent.

Read more: Who’s the kid at the end of Endgame?

Nick Fury, S.H.I.E.L.D., and Doctor Strange and his gang of mystic sorcerors have all been searching for other superheroes, so why wouldn’t they have found these hundreds, if not millions of mutants before now?

Having Hulk’s “snap” be ground zero for the mutation – an inverse to the Decimation – would give the concept of X-Men a neat starting point in the 11-year-old franchise. It’s pretty clear that X-Men: Dark Phoenix is intended to be the end of that saga, wiping the slate clean for a fresh start with a new cast in the MCU.

Until Marvel Studios makes any official slate announcements for the future of the MCU this is all just speculation for now. If only Doctor Strange could take a peek into the future for us, it would clear all of this up for an instant.

As for how The Fantastic Four will be introduced… your guess is as good as ours.

Avengers: Endgame is in cinemas now. X-Men: Dark Phoenix is coming 5 June, watch a trailer below.