Warning - This article contains spoilers for WandaVision Episode 7.
For the first time, after seven episodes, WandaVision finally has a mid-credits scene as is typical of the films in this franchise. It was rather short, like all post-credit scenes, but it gives more clues about who Evan Peter's “Pietro Maximoff” might be and his relation to Kathryn Hahn's Agnes, now officially revealed to be Agatha Harkness. A character with a long and complicated history with Wanda Maximoff.
In this sequence, Monica Rambeau, persistent, follows Wanda to Agatha's home. Trying to find a way inside, Monica finds the doors to the basement. When she opens them, she sees creeping vines with a purple glow around them. Suddenly, Evan Peters, who was missing since Wanda blasted him, returns telling the S.W.O.R.D. agent that “Snooper's gonna snoop.”
Earlier in the episode, when Billy asked about “Uncle P,” Wanda told both him and Tommy that he wasn't really their uncle. Pressed further about whom he actually is, Wanda can't come up with an answer, but this episode and ending may have given fans more clues.
FOX'S PETER MAXIMOFF
According to Hahn's little song, she was directly responsible for Evan Peters appearing on Wanda's doorstep, signified by the hazy purple surrounding him with her just outside. As many have speculated, it could be that by being unable to recreate Wanda's brother perfectly, another version of him was plucked from a different reality.
Once and for all establishing the concept of the multiverse in the MCU that was only teased in Spider-Man: Far From Home with Mysterio. It could be that, after Wanda's complete distrust in him, Agatha is having Peters act as an enforcer instead, protecting her spooky basement from “snoopers” like Monica. It would be interesting to see if, like Vision, Monica will have the ability to people back to their senses and could maybe do the same for whoever Peters is playing.
ANOTHER PIETRO MAXIMOFF
As revealed by Jamie Foxx, he won't be playing the same Electro he did in The Amazing Spider-Man 2 and that it would be a new incarnation of the character. It is still entirely possible that the same could be the case for Evan Peters' simply playing a new iteration of Quicksilver. It would certainly avoid dangling the possibility for audiences to see other X-Men actors return, which seems to be less and less likely by the day.
Frustrating for fans, but still a possibility, while also fulfilling the same role, in addition to preparing audiences for what will be the case in Spider-Man 3 with all the returning actors. It's looking more and more likely that they won't be playing their original characters, but new versions of the same villains. Might as well cushion audiences' expectations on that front now rather than later.
Perhaps the most controversial theory is that Peters is playing Nicholas Scratch, the son of Agatha Harkness. Most of this actually stems from Harkness' pet rabbit, Señor Scratchy, who makes a return this episode. Also, as silly as it may be, neither the rabbit and Peters are seen in the same room together. It could be that through Agatha's own magic, she made him look as close to Wanda's Pietro as she could, hence the need for her magic.
After all, Monica seemed to be rather shocked when she was looking at him, so perhaps her new vision showed his true form?
Although, it seemed like Monica was put under the same spell Wanda was by Harkness at first, only this time by Evan Peters. Upon closer inspection, when Monica first opens the basement doors her eyes had already turned that shade. So, it's likely that Monica is using her newfound powers to “see” the purple haze surrounding the vines. Meaning that it's unlikely that it was Peters' using his own magic on her.
Again, a big stretch, but at this point, it'd seem odd for Pietro to be any kind of puppet master unless this all ends up being a double fake-out, and he ends up being Nightmare or Mephisto like many first expected. As for how Monica and Pietro will interact in the next episode, it could be her first real test using her new powers, although, Peters, fake or not, has already displayed his use of super speed, which could pose a challenge to the new super powered agent.