Warning. There are Spoilers ahead. WandaVision is turning out to be the most unexpected entry in the entire MCU so far. Not only is the show setting up Wanda Maximoff aka Scarlet Witch as a villain, but the fifth episode of the series stunned fans by introducing Evan Peters as his character Quicksilver from Fox's X-Men movies, who is now officially Wanda's long-lost twin brother. WandaVision showrunner Jac Schaeffer recently explained that a great deal of thought went into planning Quicksilver's entry in the MCU.

"We loved the idea of [bringing him back]. And then we were like, how in the world are we going to make this make logical sense? Like, how do we justify this? Because that's the thing, you can hatch a million great ideas, but to make them land, to make them be grounded, to make them feel organic to the larger story... This show is such a mind scramble, and because it's working on so many levels, and there's so many notions of what's real and what's not, and performance, and casting, and audience, and fandom, and all of that, we just thought it would be the biggest thrill to bring Evan over to the Marvel Cinematic Universe."
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Peters first showed up as Pietro Maximoff aka Quicksilver in X-Men: Days of Future Past. Over time, Pietro realized that Magneto was his father, but there was no mention of his twin sister Wanda, who existed in the MCU alongside Aaron Taylor-Johnson's Quicksilver. For Schaeffer, adding Peters into the mix fell perfectly in line with WandaVision's fondness for exploring sitcom tropes, which in this case places Quicksilver in the role of a kooky sitcom uncle who drops by for an unexpected visit.

"We thought like, how do we give him this entrance, and then enjoy that, and then make it crazy? And we had long had the idea of the trope of the brother, or the relative, or whoever comes to town and like, stirs things up with the family - that sitcom trope... We were rooting for it for so long, and didn't know if it would be possible. It was complicated to make happen. Evan was always up for it - like, always, always, always. He is a comic book fan, and a Marvel fan. He is always up for the absolute weirdest option. And he's a pleasure - truly a pleasure to work with. Everybody was really excited. I think Kevin [Feige, Marvel Studios president] wanted to make sure that there was a reason for it, that it made sense. And I hope that's what we did."

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. The show takes place in an artificial reality that Wanda has constructed for herself and her android boyfriend Vision modeled on classic sitcoms. New episodes air Fridays on Disney+. This news comes from Marvel's deep dive into Quicksilver's cameo.