The following contains major spoilers for WandaVision Episode 5. If you have yet to see the episode, this is your last chance to turn away.

　　WandaVision Episode 5 was extremely creepy, sure, but it also pulled off one of the biggest and most meta twists in MCU history by reintroducing a long-dead character in a completely unexpected (and deeply sitcom-ified) way.

　　Pietro Maximoff, AKA Quicksilver, is back. But he's been very literally "recast." Aaron Taylor-Johnson, who played Pietro in Avengers: Age of Ultron has been officially replaced in the MCU by Evan Peters, who played Pietro in Fox's X-Men movie franchise. And to make matters even stranger, people in the universe of the show are aware of the change--the comment about "recasting" the role comes directly from Darcy Lewis (Kat Dennings) as she observes the show-within-a-show from the SWORD base.

　　We'll give you a second to process that. Seriously, just let it sit for a moment.

　　If you're left wondering what this could possibly mean for the MCU at large, you're not alone.

　　The inclusion of the X-Men within the MCU has been a hotly debated and widely discussed topic since Disney purchased Fox, and the rights to the franchise, back in 2019. Peters' inclusion in WandaVision is the first official move to bridge the gap between the two universes and undoubtedly paves the way for more potential X-Men and mutant outings in future MCU shows and movies.

　　However, the fact that this is all taking place within the Westview anomaly also makes it hard to count as a certainty. Wanda's apparent psychotic break aside, she maintains that bringing Pietro to the house wasn't something under her control, meaning he was sent in by someone--or something--likely influencing the parts of Westview that aren't under Wanda's immediate power. Which, of course, begs the question of whether or not Pietro is even real at all or will have the ability to leave the "hex" (as Darcy has dubbed the Westview bubble).

　　On top of that, there's also the outsiders' awareness of Pietro's change. The MCU has recast roles before--Rhodey was played by Terrance Howard in the first Iron Man movie, and then Don Cheadle in every subsequent MCU movie--but the change was done from the outside and didn't actually affect the in-universe characters at all. If Pietro is indeed an actual person and not some fabrication, it's likely that this is our first actual glimpse of the MCU's multiverse in action, bringing the Pietro of the Fox X-Men Earth over to the MCU Earth.