A lot of fans were disappointed when WandaVision didn't reveal Mephisto as its big bad, and as of right now, there are no signs that the demon is actually coming to the Marvel Cinematic Universe. If nothing else, Marvel Studios is finally aware of how much fans want to see him in live-action, but how does Kathryn Hahn feel about all those fan theories?
The Agatha Harkness reveal was one fans saw coming a mile off, but that made the villain no less effective. As for Hahn, she kept off social media, but was aware that the majority believed Agatha must be reporting to Mephisto.
"Yes, I knew there were a lot of theories leading up to this show. I mean, the noise, that was kind of one of the most fun things for me not being on social media was to hear from friends how much noise was happening while the show was going on," she recalls in the video below. "I remember hearing that I was there as a puppet for Mephisto, that was a theory that I heard, and I had to immediately say, ‘Who is Mephisto?’ Don’t hold that against me! Now I know who Mephisto is."
Unless the entire cast and creative team is trolling us at this point, it's clear that there were never any plans for Mephisto to appear or be referenced in WandaVision. That's strange when there were so many demonic hints early on, but that could have simply been a way of teasing Agnes' true identity as a witch (Agatha may well worship the devil, even if she's never met him).
One popular theory is that Mephisto will factor into Loki, though Doctor Strange in the Multiverse of Madness is also a possibility. Check out Hahn's comments in full below: