WandaVision: 5 Predictions For Who The Final Episode's Secret Cameo Is

Ever since the first two episodes of WandaVision dropped on Disney+, there has been no character theorised to appear more than Mephisto. Like Agatha said, the details aren't the only place the Devil is, possibly foreshadowing the fact that he has been living inside her pet rabbit, or potentially as a lingering presence elsewhere in Westview.

At this point, after the way she spoke with him in episode eight, it would almost be more surprising if Señor Scratchy wasn't revealed to be someone in disguise. Though there are several villains that could potentially be working with Agatha Harkness, Mephisto would be the prime candidate.

Hints and clues have been dropped like breadcrumbs throughout WandaVision, with many of them pointing towards Marvel's Devil. Both Agatha and Wanda's twins have deep rooted connections to the villain in the comics, as the boys are made of fragments of Mephisto himself, and when Fake Pietro called them Demon Spawn on Halloween, many fans were convinced he still had some role to play.

Mephisto is also rumoured to appear in Loki later this year on Disney+, and since such a villain would be more suited to take over from Thanos as the franchise's big bad rather than appear just once, a potential debut in the WandaVision finale could just be the beginning.