Warning: Contains SPOILERS for WandaVision episode 5, "On A Very Special Episode."

Pietro Maximoff, aka Quicksilver, appears at the end of WandaVision episode 5, but this time he's played by Fox X-Men star Evan Peters, rather than Aaron Taylor-Johnson, who had previously played the MCU character in Avengers: Age of Ultron. One of the primary themes of WandaVision is Scarlet Witch's trauma, as it explores how her past has impacted her and led to the events currently unfolding in Westview, for which she is at least partially responsible. The death of her brother, Pietro, is a major part of that, because it was one of several devastating losses Wanda has had to endure. WandaVision episode 3 set up Quicksilver as being important when his death was referenced by Geraldine, aka Monica Rambeau, and now WandaVision episode 5 has taken that even further.

"On A Very Special Episode," once again mentions Pietro, as Wanda's twins, Billy and Tommy, ask their mom if she has a brother. A shaken Wanda begins to recollect that she does, but that he's "far away," which makes her "sad sometimes." That tease once again hinted that Pietro may return in some way, and it paid off at the end of the episode, when a knock at the door revealed Quicksilver... only this time played by Evan Peters, not Aaron-Taylor Johnson. Peters made his debut as the character with a scene stealing turn in X-Men: Days of Future Past, before returning in X-Men: Apocalypse, Deadpool 2, and Dark Phoenix.

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Peters appearing as Quicksilver in WandaVision isn't entirely surprising, as his casting for a mystery role had previously been reported, but it's nonetheless exciting to see it happen. It does, however, beg the question of why Marvel decided to recast the part. Back in 2019, Taylor-Johnson told Screen Rant Quicksilver wouldn't return anytime soon, though he was "open" to the idea. The actor has been busy with other projects, including Tenet, The King's Man, and Bullet Train, so it's possible that his schedule simply didn't allow for him to return, or that he didn't wish to, if indeed there were ever any plans for him to do so. That makes some sense, but Quicksilver's recast also better fits with what WandaVision (and more broadly, the MCU) is doing.

In terms of WandaVision specifically, the idea that Quicksilver has been "recast" (as Darcy herself notes) not only adds a meta-touch to its sitcom styling, but further ties in to all not being right in Westview. Quite how and why Pietro appears is unclear, but the suggestion is that it's not something Wanda herself did, or at least, not consciously. Whether things are spiralling out of Scarlet Witch's control, or someone else is really running things, having Quicksilver be recast as Peters works to better showcase that. There may well be more to Peters' Pietro than meets the eye, too, with him being a puppet of, or just literally being, someone like Mephisto, Nightmare, or another villain who could be the series' real big bad.

The recasting also ties in to Scarlet Witch saying that she cannot bring people or animals back from the dead in this episode. That's in reference to Sparky, but it neatly slots into what's shown with her reclaiming Vision's body, yet clearly not being able to fully bring him back proper, as evidenced by Vision's appearance as a corpse in WandaVision episode 4. Wanda cannot bring Aaron Taylor-Johnson's Quicksilver back, which means the next best thing is Evan Peters' version of the character.

This all serves to nicely set up the MCU's multiverse as well, something that WandaVision was already teasing, but makes even more overt here. Spider-Man: Homecoming 3 will see characters from different franchises coming to the MCU in some way, whether as their old selves or new versions of the them. Having Peters as Quicksilver helps better introduce that idea in preparation for Spider-Man 3, while also laying groundwork for the X-Men's true MCU introduction later down the line as well. Quite how it all pays off remains to be seen, but by recasting Quicksilver as Evan Peters, then the MCU opens up a whole world of possibilities that people might not have seen coming.

Next: Marvel Confirms When WandaVision Is Set In The MCU Timeline