The nine-episode arc of WandaVision was absolutely packed with secrets, whether we're talking about the identities of certain characters, the initial mystery behind the source of Wanda's sitcom world, or the nature of Vision's very existence. It was so packed with secrets, it turns out, that some plot elements were written as mysteries — only to end up being revealed before the series even premiered. 

Speaking to The Hollywood Reporter in one of several post-finale interviews for WandaVision, head writer Jac Schaeffer explained that the series writing team had at least one major mystery in mind that Marvel Studios decided to reveal to audiences more than a year before the show's premiere. That mystery? The identity of Geraldine, the mysterious new Westview resident who's just showed up in town and seems to know a little more than everyone else. As Schaeffer explained, the show's original intention was to keep Geraldine's real identity, Monica Rambeau, a secret until midway through the series. Marvel had other plans. 

"Yeah, Teyonah [Parris, who plays Monica] was announced at Comic-Con 2019, I think, and I'm pretty sure we were breaking the outlines and writing as though it would be a surprise," Schaeffer said. "But Marvel and Disney have incredible strategy when it comes to the PR side of things. They're so smart, and they know how much to give and how much to hold back. So when that dropped, the jig was up. In the linear watch of the show, when she first appears, she's referred to as Geraldine. So it ended up being the opposite of what we intended, and people were like, 'Geraldine? But she's Monica Rambeau!' So that ended up being a fun reversal."

As it unfolded for viewers, despite the knowledge that Parris had already been confirmed as Monica Rambeau, the Geraldine reveal did still achieve a certain level of mystery, but it was more about the "Why?" than the "How?" of the character's journey. We already knew who she really was, but her point-of-view as someone who'd been sucked into Westview and profoundly altered by it did serve as the audience entry into the world of S.W.O.R.D., as well as the explanation for what the Hex surrounding the town actually was. Plus, meeting Monica as "Geraldine" first seemed to actually enhance the impact of learning her real identity, particularly since Monica herself underwent such a major evolution over the course of the show. 

Of course, it wasn't just Marvel's expectations which changed the experience of the show for a lot of viewers. Even for a Marvel property, WandaVision was beset by fan theories very early on, which meant the show then caught backlash when the most popular of those theories didn't come true, which meant that some viewers were never going to be pleased by the show because their idea of what it was supposed to be was already set in stone. For Schaeffer, that's all part of the experience of crafting a mystery story, something she's already game to do again. 

"This was my first mystery and I love it so much. What I loved the most was breaking it in the room — the actual puzzle of it and working with my extraordinary team of writers," Schaeffer said. "The science of it was so satisfying as a writer and craftsperson. It was so much fun. And the experience of watching an audience theorize and communicate with each other was also so much fun. Everyone was just having a good time, and everybody was engaged. The thing that you want more than anything, as a creator of content, is for people to be engaged, and a mystery is certainly the way to do it."