[Warning: The following contains spoilers for WandaVision Episode 5. Read at your own risk!]
Holy Quicksilver! WandaVision pulled off its biggest "Oh my God!" moment yet at the end of Episode 5 when Evan Peters showed up in Westview as Wanda's (Elizabeth Olsen) thought-to-be-dead brother, Pietro. Of course, Peters is not the version of the character people might be expecting. Peters played Pietro, aka Quicksilver, in the X-Men universe, beginning with X-Men: Days of Future Past, while Aaron Taylor-Johnson played the MCU version of the character, who died in Avengers: Age of Ultron. Peters showing up as Wanda's brother at the end of Episode 5 indicates that the multiverse has started to open within the MCU, which is what we've all been waiting for, as WandaVision will set up the film Doctor Strange and the Multiverse of Madness, due out in theaters next year.
Episode 5 marks the official halfway point of WandaVision's first season, so it's appropriate timing for a huge twist. Pietro showed up just as Vision (Paul Bettany) was finally confronting Wanda about what exactly Westview is and what she must be doing to create the sitcom reality around them. While Wanda denied Vision's allegations, it had already become clear earlier in the episode during a confrontation with the SWORD agents outside of the Westview bubble that Wanda was in complete control of the bubble, and she had no intention of stopping if this was her only means of a happy ending with Vision.
Wanda may not be as in control as she wants SWORD to believe, though. It was clear that she was not expecting the Pietro twist either, and Darcy's (Kat Dennings) exclamation back at SWORD headquarters signaled that Pietro's new face means something much bigger is going on. Cue the multiverse! The existence of the multiverse means that different versions of all Marvel characters could begin popping up anywhere in the MCU (and adds fuel to the rumors that multiple Spider-Men will show up in Spider-Man 3, which is set for its theatrical release at the end of 2021).
Of course, we won't know for sure what this means until next week's WandaVision, but if the indicators are correct, then this is a game-changing move for the entire Marvel Cinematic Universe, not just this series. Buckle up, because it's only going to get more wild from here.
New episodes of WandaVision drop Fridays on Disney+.