WARNING: The following contains spoilers for WandaVision Episode 5, "On a Very Special Episode...," now streaming on Disney+.
It's no secret the multiverse is coming in Phase Four of the Marvel Cinematic Universe. Indeed, there are already signs the MCU plans to dip more than its toe into the multiverse before Doctor Strange in the Multiverse of Madness dives head-first into the concept. The MCU even started its reintroduction of actors from other Marvel cinematic universes with the latest episode of WandaVision, bringing in Evan Peters as "Pietro." What's more, whoever Peters is actually playing could explain the presence of certain villain actors in the MCU's Spider-Man 3.
For months now, it's been reported Alfred Molina is reprising his role from Sam Raimi's Spider-Man 2 as Doc Ock in the MCU's Spider-Man 3, with Jamie Foxx also returning as Electro from Marc Webb's The Amazing Spider-Man 2. However, that's really just the tip of the iceberg when it comes to actors from Sony's pre-MCU Spider-Man movies rumored to be coming back for the Spider-Man: Far From Home sequel. However, the big question is whether Spider-Man 3's versions of villains like Doc Ock and Electro are from their respective Marvel movie universes or are re-imagined versions of the characters with a different backstory.
This is where Peters' appearance as Pietro comes in. WandaVision Episode 5, "On a Very Special Episode...," ends with Peters showing up at Wanda and Vision's home in Westview, completes with the silver hair he had when he played Peter Maximoff/Quicksilver in Fox's X-Men films. The show acknowledges this is a different Pietro than Aaron Taylor-Johnson's version of Quicksilver from the MCU, with Darcy Lewis even cracking a meta-joke about Pietro being "recast." And yet, Wanda seems to fully believe this is her brother, which raises questions about who, exactly, Peters' character will turn out to be.
It's possible Peters is playing someone from the MCU who's posing as Pietro to gain Wanda's trust. In that case, the actor's casting could just be WandaVision's way of misleading its viewers. On the other hand, Peters may well be reprising his superhero from Fox's X-Men universe. If so, Spider-Man 3's Doc Ock and Electro could similarly be the same versions of the villains from their respective Spider-Man film series. Then, of course, there's the third option: if Peters is playing a new take on Wanda's brother who's originally from the MCU, then Doc Ock and Electro may not have any ties to their onscreen past either.
The idea of WandaVision's Pietro and Spider-Man 3's villains all originating in the MCU is certainly an intriguing one. In addition to serving as a way for the MCU to organically incorporate these actors into its setting, it would allow the franchise to explore who these characters might've been in another life, compared to who they were in other Marvel movie universes. It's already been pointed out Foxx's return as Electro gives him a chance to redeem his previous performance and even the actor has assured this portrayal will be different from his earlier one, teasing Electro "won't be blue" in a since-deleted Instagram post.
Alternatively, WandaVision introducing Peters to the MCU could be Marvel Studios' way of working up to the full-blown multiverse storylines in Spider-Man 3 and the Doctor Strange sequel. For example, it's possible Wanda (or someone) brought Peters' Quicksilver over from Fox's X-Men universe into the MCU to "play" the role of her brother, in the process wiping his memory for the time being and creating a hole in the fabric of the multiverse that could create bigger problems later. Really, whichever way you cut it, odds are the truth about Peters' Pietro will have major implications for what's really happening in the MCU.
Written by Jac Schaeffer and directed by Matt Shakman, WandaVision stars Elizabeth Olsen as Wanda Maximoff/Scarlet Witch, Paul Bettany as Vision, Randall Park as Agent Jimmy Woo, Kat Dennings as Darcy Lewis, Teyonah Parris as Monica Rambeau and Kathryn Hahn as Agnes. New episodes air Fridays on Disney+.