Some Marvel fans were disappointed that Mephisto, one incarnation of the Devil in the Marvel Universe, didn't appear in WandaVision. Mephisto has a history of messing with Wanda Maximoff and Vision and was instrumental in the birth/creation of the couple's twin sons, Billy and Tommy, in the comics. This history and some perceived clues led to many fan theories about Mephisto in WandaVision, expectations that he'd appear, and frustration when he did not. Whether those expectations were ever fair is a matter for fans to debate, but WandaVision showrunner Jac Schaeffer explained why Mephisto didn't show up. In short, she felt the show didn't need him.
"We didn't think this series needed a big bad," Schaeffer tells Deadline. "I mean, the big bad is grief, you know, and that's the story that we were telling, and then we got a bonus baddie in the form of Agatha Harkness who ended up facilitating Wanda's therapy, so yeah, I think we feel pretty good about that.
While there may never have been Mephisto plans for WandaVision, there was one demonic entity whose role in the show's finale didn't make it to screen. That's Señor Scratchy, Agatha Harkness's "rabbit."
"We did have something more planned for Senor Scratchy which we ultimately couldn't do just because the finale we had so many different chess pieces on the... we did have a whole sequence where Darcy (Kat Dennings), Monica (Teyonah Parris), and Ralph (Evan Peters) meet up with the kids and they're in Agatha's house and they think that maybe the should steal the Darkhold from the basement because the kids had seen it when they were down there being held hostage by Agatha," director Matt Shakman revealed on an episode of Fatman Beyond. "They go down there to get the book, you're reaching for the book, and the rabbit hops up in front of the book and then we go 'Senor Scratchy, he's the best!' and they like reach over to pet him and hie hisses and then this whole American Werewolf in London transformation happens and the rabbit turns into this big demon right, into her like familiar. And then, Goonies set-piece ensues with all sorts of fun as they try to escape from the rabbit. We shot it but didn't finish all the VFX and stuff for it. And it was, it was a great sequence. It was super fun, everyone was great in it, but we ended up moving it aside because it was a huge sort of detour in the middle of everything else that we had going on so, yeah, Señor Scratchy did have a little bit more left on the cutting room floor."
WandaVision is now streaming in its entirety on Disney+.