Logan, the 2017 X-Men spin-off that served as Hugh Jackman's final go-around as Wolverine, did not take place in the Marvel Cinematic Universe. However, as a new fan theory puts forth, it may explain how mutants end up in the MCU. Or at the very least, explains where they came from. If true, it would add a new dimension to director James Mangold's movie.
The theory was shared on Reddit recently. Posted to the MCU Theories subreddit, it comes from user electron-shock. It essentially posits that mutants were transported to the MCU from the Fox X-Men universe. Given some of what we've seen recently, particularly in WandaVision, that would seem to make sense. It also explains that Charlex Xavier was not responsible for killing many of his mutant counterparts in the "Westchester Incident," as it is referred to in Logan. The theory reads as follows.
"Professor X didn't kill the XMen as described in Logan. They were pulled into the MCU and Prof X took the blame in the confusion. The multiverse tear is also what 'broke' Xaiver."
Warning: the rest of this post will contain spoilers for WandaVision. Read on at your own risk. The most recent episode of WandaVision contained a bombshell cameo in the form of Quicksilver. But not Aaron Taylor-Johnson's Quicksilver who we met in Avengers: Age of Ultron. Instead, it was Evan Peters' Quicksilver from X-Men: Days of Future Past and Dark Phoenix. This has universe-shattering consequences. It remains unclear, as of this writing, how Quicksilver made his way to the MCU. But this theory explains, to some degree, where he came from. And, moreover, that the effects of mutants being teleported to the MCU from an alternate universe will have consequences in that universe.
As for the Westchester Incident, for those who need a refresher, it was a major plot point in Logan. Professor X has a degenerative brain disease that caused him to have seizures. We got a glimpse of this in the Las Vegas scene. Through proper medication, those occurrences can be kept at bay. But the incident in question, which we never actually see on screen, is alluded to several times. Lots of mutants died. Or it at least appears that way. This theory, instead, suggests that the mutants, somehow, were pulled into the MCU at that moment. But Charles was left to shoulder the blame, and the guilt that came with it.
Whether or not this theory holds any water, in the end, remains to be seen. What we know for sure is that the multiverse is coming to Phase 4 of the MCU, and WandaVision has already ripped it open. It will, additionally, be explored in the untitled Spider-Man 3, which will bring back characters from previous versions of the Spider-Man franchise, as well as Doctor Strange in the Multiverse of Madness. Both movies are currently in production. So, as fan theories go, this one is at least plausible. This news comes to us via Reddit.