Mutants are dying in the Marvel universe, and it’s unclear what’s killing them. The upcoming Wolverine film Logan illustrates a world in which mutants have been wiped to near extinction, forcing Hugh Jackman’s character to save and care for a mutant named Laura.

So, what exactly in Marvel’s X-Men-centric cinematic universe killed off the mutants? What if the outbreak that occurred after the events of X-Men: Days of Future Past wasn’t the Legacy virus, which appears in the comics, but Terrigen Mist from the mainstream Marvel Cinematic Universe? As in, the Avengers-verse?

Let’s back up. In the Marvel Comics-based Universe, there are two kinds of altered people: Mutants, who suddenly receive powers at adolescence due to genetic mutation, and Inhumans, an alien race who migrated to Earth eons ago and whose DNA lies within individual human beings. Inhumans get their powers when exposed to Terrigen Mist and undergo Terrigenesis. Ms. Marvel, for example, is an Inhuman.

Here’s the thing with Terrigen Mist: It’s harmful to mutants. In the 2013 crossover Inhumanity, a Terrigen Bomb unleashed Terrigen Mist that awoke Inhumans but sterilized mutants.

In the MCU, a Terrigen outbreak occurred at the end of Season 2 of Marvel’s Agents of S.H.I.E.L.D. when the chemical was unleashed in the ocean. Anyone who came into contact with fish oils — which is in all sorts of medicine — might get superpowers. Those who did have been appearing in the ABC series.

Here’s the exciting part: After some negotiation, it’s possible that Fox’s X-Men continuity could end up sharing its universe with the Marvel Cinematic Universe, which means the Terrigen outbreak in Agents could cause the extinction of mutants post-Days of Future Past. Those events would set up the events in Logan.

Of course, this is a stretch due to the divide between Disney-owned Marvel Studios, which owns the Inhumans in concept, and 20th Century Fox, which obtained the rights to X-Men from Marvel in the ‘90s. In recent years, the X-Men were pushed to extinction in Marvel’s comics universe by way of a Terrigen Bomb, a weapon that killed nearly all mutants but allowed Inhumans (an alien race whose DNA sleeps within humans) the chance to emerge.

Marvel’s choosing X-Men in favor of Inhumans was interpreted by critics and fans as diminishing the importance of characters the company doesn’t own cinematically. Sinking time and energy into X-Men comics means giving rival Fox good material for their own movie franchise, so why bother?

In April, a planned movie, Inhumans, lost its 2019 release date and no follow-up plans were announced. In July, at San Diego Comic-Con, Marvel announced an Inhumans vs. X-Men comic, a crossover pitting the two races against each other.

In October, Marvel announced a whopping seven new X-Men books for 2017 in an initiative titled “ResurrXion”, which includes the return of X-Men: Blue and X-Men: Gold, the flagship X-books from the ‘90s — a decade when the X-Men were the most dominant franchise in comics.

Again, there has been no formal announcement that Marvel Studios has set up a deal akin to Sony and Spider-Man in an effort to include the X-Men into the Avengers film franchise. There is no cinematic or televised crossover, officially. But with all that’s going on in the comics with mutants and regarding the Inhumans, some fans are hoping to see Nick Fury stride into Logan and tell the mutants he’s been watching them all along.

Photos via 20th Century Fox