WARNING: The following contains spoilers for WandaVision Episode 5, "On a Very Special Episode...," now streaming on Disney+.
What Marvel characters might make appearances in WandaVision has been a frequent topic of speculation. Guesses have ranged from Tony Stark to Ultron to personalities from the comics that have yet to be brought to life in the Marvel Cinematic Universe. Episode 5, "On a Very Special Episode..." doesn't necessarily preclude any of those theories from coming true later on, but the smart money was on Wanda's twin brother, Pietro Maximoff, all along. We saw a Pietro in in the episode, but why he's appeared on WandaVision is still ripe for further theorization.
For fans who seek out spoilers, Pietro's last-second cameo in Episode 5 wasn't so much a surprise as it was a matter of time. Casting and merchandising leaks revealed Quicksilver would eventually factor into the Disney+ series, but it was Evan Peters' name on the cast list, not Aaron Taylor-Johnson's. Taylor-Johnson starred alongside Elizabeth Olsen in Avengers: Age of Ultron, the film in which the Maximoff twins made their MCU debut. Taylor-Johnson's Quicksilver heroically sacrificed himself at the end of that movie, a painful fact that Monica Rambeau as "Geraldine" reminds Wanda of in Episode 3 before she's promptly expelled from Westview. Evan Peters was Fox's Quicksilver in the most recent series of X-Men movies. Now that Disney has acquired Fox, it owns the rights to those storylines and characters, too, so both versions of Quicksilver are fair game.
With the anticipated introduction of the concept of multiverses into the MCU, Disney had practically infinite ways to incorporate either version of Pietro into WandaVision and the wider MCU. When fans saw Peter's name, many expected that his Quicksilver would somehow be used to unify the two intellectual properties. Then the show leaned hard into Taylor-Johnson's character's death. Instead of resolving inconsistencies or referencing pre-existing canon, WandaVision seems to be employing Pietro as yet another symbol of Wanda's grief.
In Episode 5, we learn via a S.W.O.R.D. meeting that Wanda confiscated Vision's corpse and escaped with it to Westview, where she brought it back to life. Agent Woo makes it clear that this is morally black-and-white territory. Reanimating the dead definitely runs counter to the Sokovia Accords. Meanwhile, Vision continues to uncover the truth about his distorted reality, first when Agnes makes a mistake and asks for a redo, as if they're in a rehearsal, then at work when Darcy hacks into his company's email and a co-worker has an epiphany. Westview might be surreal but it is real. Wanda is -- to some extent -- controlling actual, physical places and people, including her zombified husband.
How much of it is conscious is another matter altogether. At the midpoint of the episode, when an armed drone becomes one intrusion too many to bear, Wanda leaves the security of her bubble and confronts a hostile Tyler Hayward and a more gentle Monica Rambeau. But she's either unaware, playing dumb or conveniently compartmentalized her role in her sitcom reality when Vision points out its fissures. A subplot involving her twins' desire for a pet dog ends in tragedy when the pup, Sparky, dies the day they adopted him. In an extremely creepy, knowing way, the kids beg their mom to correct the situation and "fix the dead." She's slightly horrified by the idea and says no. However, Sparky's untimely death may have sparked a dormant memory in Wanda's powerful but tortured mind.
To Wanda, "fix the dead" could also refer to Vision and Pietro. We already know she's "fixed" Viz, so when -- after a tension-building second knock on the door -- a tuft of a man's white hair appears, shot from behind, it's reasonable to suspect she might have "fixed" Taylor-Johnson's Pietro, too. Instead, the special guest is Evan Peters, cracking wise in a major tonal shift. "She recast Pietro?" Darcy says to the vintage television on which she's watching events unfold. The implication is that this is Wanda's doing, but Wanda swears to Vision it's not. There's also no hard and fast confirmation that this is X-Men's Quicksilver.
Since it's been established that everything that's happening is happening not in code in the confines of an old TV set, but just on the other side of a forcefield in the real world, viewers can be assured there is a person who believes himself to be Uncle Pietro standing at Wanda and Vision's doorstep. We'll have to wait to find out whether he's a recast (in-show and in the meta sense) Quicksilver, a creation of Wanda's trauma, an imposter or someone sent in by another party. In any case, Wanda and Pietro's story is unlikely to resolve as quickly and easily as things do in '80s sitcoms.
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+.