Warning: major spoilers for Avengers: Age of Ultron and the comics crossover event House of M ahead.

In 2015’s Avengers: Age of Ultron, Marvel Studios introduced the speedster hero Quicksilver — and then promptly killed him off. There are a lot of potential reasons for Pietro Maximoff to die in the film series, rather than joining the Avengers with his sister Wanda, aka the Scarlet Witch. Marvel Studios may have wanted to avoid confusion with the version of Quicksilver appearing in the X-Men films. Avengers Tower was getting pretty crowded, as the MCU built up more and more characters. The film was also scripted and directed by Joss Whedon, who has a track record of killing off heroes at the ends of his stories. But the best reason for killing Quicksilver might have been to make Wanda suffer — and set up a chain of events that will fix Marvel’s big upcoming continuity problem in the process.

The same thing goes for Vision. There’s already been plenty of speculation about who might die in Avengers: Infinity War, and he’s one of the prime suspects. He and Scarlet Witch are romantically involved in the comics, and the films have been trending in that direction as well. The Infinity War Super Bowl teaser trailer offers a moment of intimacy between them. It also shows the Infinity Stone that originally helped create Vision being ripped out of his head. The stone could certainly be recovered, or the Avengers could find a new way to bring him back. But the important part of the story isn’t how the Avengers fix the problem. It’s how Scarlet Witch reacts, and where the story goes from there.

In Marvel’s 2004–2005 Avengers Disassembled comic book arc, Scarlet Witch is responsible for the deaths of Vision, Ant-Man, and Hawkeye. (The latter two are noticeably absent from the Infinity War trailers.) Her grief and guilt led to Brian Michael Bendis’ 2005 crossover event House of M, where Scarlet Witch uses her powers to remake the world so she and everyone she loves can be happy. An eventual House of M plot in the MCU could solve a big problem for Marvel Studios: how to integrate the X-Men and Fantastic Four, which it’s bringing back into the fold when the merger of Disney and 21st Century Fox is completed in summer 2019.

House of M is an Avengers / X-Men crossover event, but since 21st Century Fox has the rights to the X-Men for movie releases, it was impossible for Marvel / Disney to take on the plotline before that merger. Marvel Studios president Kevin Feige has said he hasn’t made plans for the X-Men yet since he wasn’t aware of the impending merger. With the X-Men rights back in Marvel’s hands, though, House of M is potentially a perfect way to blend the two universes. The comic series leans on the most traditional backstory for the Maximoff twins, where they are Magneto’s mutant children. Wanda wants to please her mutant supremacist father, so in her world, mutants — homo superior — have been accepted as the future of humanity, with regular homo sapiens relegated to second-class citizen status, and expected to become a minority within the decade.

The turning point in events came from an alternate version of Watergate where an anti-mutant conspiracy leads to Nixon’s downfall, a storyline that could play pretty well with the timeline of the current run of X-Men films. In Wanda’s world, Magneto and his children rule the nation of Genosha, hosting swanky balls attended by international royalty, including King T’Challa of Wakanda.

Like any good alternate-universe story, House of M was a way to show what its characters really value. In the comic, Wanda creates her world while psychically connected to X-Men leader Charles Xavier, using his telepathy to read the desires of all her friends and allies. That obviously wouldn’t be an option for a House of M movie, but Age of Ultron gave Scarlet Witch her own psychic powers, seen in her ability to create illusionary worlds based on the Avengers’ memories. That’s a far leap from the incredible reality-warping powers Wanda has in House of M, but with the Infinity Stones in play, she could get a serious power boost, or her abilities could be eventually be explained as glimpses into the other worlds she can access.

But what’s important is that after she revises the world, many of the heroes have very different lives. Captain America was never frozen in the 1940s, and he’s become a senior citizen. Doctor Strange is a psychologist rather than a wizard. Peter Parker is a celebrity wrestler happily married to Gwen Stacy, with a son doted on by his Uncle Ben and Aunt May. After years of movies devoted to having ever-larger groups of heroes race to stop increasingly powerful villains who want to control or destroy entire planets, this storyline could provide some needed relief by dialing back on the stakes and focusing on humor and character development.

Still, some characters are happiest when they’re fighting. So, naturally, House of M features an underground resistance to mutant rule, led by Luke Cage and Hawkeye. They spend a lot of time battling S.H.I.E.L.D., which has become home to some of the most notable members of the X-Men and Brotherhood of Mutants. Given that Netflix’s MCU shows have only made oblique references to the films, it’s unlikely Cage would actually appear in a House of M movie. But Agents of S.H.I.E.L.D has a history of tying its arcs into the latest MCU film, which could enable a great storyline for the show, where mutants take the lead and humans are there to support them.

House of M’s greatest weakness may be in how little argument there is among the heroes once Wanda’s manipulations are uncovered. Both Avengers films and Civil War involve big fights between good guys who have very different perspectives. Seeing how loss, experience, and their views on their role in the world affect their views about how to handle the situation would be yet another way to build characters. In House of M, the major heroes are furious or devastated when they learn the truth, but only Spider-Woman ever argues that everyone might really just deserve to be happy and suggests they could do that best by not trying to change Wanda’s manipulations. Her world certainly isn’t perfect, with humans fading into obsolescence and fearing violence from mutant-controlled Sentinels. But it’s hard to say whether it’s overall worse than the world that came before it.

Given how much various heroes have sacrificed to save the world, some might feel they’re entitled to change it. Spider-Man wouldn’t have to lose Uncle Ben all over again, and Tony Stark might be content to live as a mundane millionaire married to Pepper Potts. Because of his advanced age, Captain America isn’t even brought into the resistance against Wanda in House of M, but if he was, he’d clearly be appalled by any world where leadership is determined by genetic superiority. Doctor Strange could be tempted to return to his old life as a surgeon, but feel an obligation to preserve the mystic order by defeating Wanda.

All of which could enable the kinds of hero-on-hero fights that provide the big combat setpieces that made Captain America: Civil War so much fun. Having the conflict primarily be between good guys — Wanda and her family included — would also be a boon for the MCU, which struggles most when it comes to finding worthwhile villains.

At the end of House of M, Scarlet Witch restores the world, with a few major exceptions. Hawkeye is resurrected, and the mutant population is drastically reduced, with major characters, including Magneto, losing their powers. That led to a decade where Marvel stories about people with unusual powers caused by genetics were more likely to be Inhumans than mutants, a decision that coincided with the film rights split. That direction hasn’t been going well for Marvel, with a failed Inhumans show and a planned film scuttled.

But this version of House of M could have the opposite effect. Age of Ultron established that Wanda and Pietro’s parents are dead, and their powers are the result of Hydra experiments where they started as volunteers but wound up as prisoners. It’s easy to imagine Scarlet Witch writing herself a happier backstory where she’s part of an illustrious family. A House of M film could even acknowledge that its characters have been living in separate universes that have been brought together by her powers. That plot point worked for the Arrowverse shows, which dealt with the integration of Supergirl after it changed networks from CBS to The CW by having the title character come from another version of Earth.

And a similar explanation could easily be accepted here. Marvel and DC have both traditionally used massive crossover events like Infinity War to reshape their continuity, cleaning up dangling or conflicting plotlines and establishing a new normal. Reality-warping powers are a good excuse to let Marvel Studios incorporate whatever characters they want from the X-Men continuity while changing any plots they don’t feel like keeping. Evan Peters’ version of Quicksilver and Michael Fassbender’s Magneto seem like obvious picks, but Charles Xavier is absent in both House of M and its immediate aftermath. Wolverine is also changed dramatically by the story, regaining his long-lost memories, which could give Marvel an opportunity to recast the character, since Hugh Jackman says he’s done with the role. Time-shifting the X-Men to bring them up to speed with the rest of the MCU would also be reasonable.

Embracing the House of M plotline would also set the MCU up to tackle another crossover event at some point in the future, like Bendis’ 2012 event series Avengers vs. X-Men, where the mutants try to use the Phoenix Force to bring their species back from the brink, and the human heroes try to stop them. Given that X-Men: Dark Phoenix is scheduled for release in 2019, the pieces are already in play for that conflict. Infinity War has been billed as “the most ambitious crossover event in history,” but if Marvel goes the House of M route and shakes the entire MCU into a new form, the studio might literally have to reach across universes to top it.