Hardcore Marvel Cinematic Universe fans are notoriously fixated on spotting Easter eggs that hint at Mephisto being the franchise's next Big Bad. This practice took off with WandaVision, leading to all sorts of theories about "the devil" (and not Agatha) being behind everything all along. When that didn't pan out, many carried their theories over to Loki Season 1, speculating the show would reveal Kang was in cahoots with Mephisto. And while that wasn't the case, it appears there's a chance Mephisto will join the MCU -- for real this time -- in Spider-Man: No Way Home.

Hunting Mephisto became a popular MCU pastime during WandaVision's run, with fans believing Wanda's hexagonal magic was linked to him, or that he created her twins, or that he was a fly on the wall inside Agatha's home, or even that S.W.O.R.D. Director Tyler Hayward's blatant hostility meant he was a shape-shifting Mephisto. Then, just as things had cooled down, a shot of a picture of a devil on a church window in Loki sent fans back down the rabbit hole.

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The big clue for No Way Home comes at the 0:39 mark of the trailer when a "devil in disguise" sign demonizing Peter Parker (Tom Holland) for duping the public is spotted. Sure, it might seem like an angry civilian simply hates how the kid pretended to be a hero, but what makes this a powerful Mephisto link and not something conjured out of thin air is the deal Doctor Strange makes with Peter. The film sees the Sorcerer Supreme messing with space and time against Wong's wishes, making it so the people of the world forget Peter is the wall-crawler.

As many comic book readers are aware, Strange's spell in No Way Home recalls the deal Mephisto made with Peter during the One More Day storyline, which took place after Peter's secret identity was revealed to the public during Civil War. While their agreement saved Aunt May's life after she was shot and killed as a result of Peter's actions, it also erased Peter's marriage to Mary Jane by making it so no one but Peter would know who was really behind the Spider-Mask.

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Otto Octavius Making a Deal With Mephisto at Anna Maria Marconi's Protest in 2019's Superior Spider-Man #11

While it doesn't take a leap to assume that Strange would be arrogant enough to attempt a spell of this magnitude (being cavalier is kind of his thing, after all), it's the casual way in which he breaks the rules of magic in the No Way Home trailer that has fans theorizing he's really Mephisto in disguise. As the argument goes, Strange should know better than to mess with the multiverse after his battles with Kaecilius and especially Thanos, so his reckless behavior only makes sense if it's not really him at all. Who knows: Maybe third time really is the charm when it comes to "the devil" being in the MCU's details.

To see how, if at all, Mephisto plays into Peter Parker's next solo outing, Spider-Man: No Way Home swings into theaters on Dec. 17.

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