'WandaVision' Director Talks Agatha, Scarlet Witch and Introducing Chaos Magic Into the MCU (Exclusive)

Plus, Fietro, Monica Rambeau and why Aaron Taylor-Johnson doesn't make a cameo.

It was The Scarlet Witch all along.

It took five movies and eight episodes, but Wanda Maximoff's comic book alias has finally been made canon in the MCU. WandaVision's penultimate episode, "Previously On," culminated in a standoff between Wanda (Elizabeth Olsen) and Agatha Harkness (Kathryn Hahn), who revealed herself to be a centuries-old witch with dubious intentions.

The entirety of episode 8 up to that moment revolves around Agatha's investigation into how Wanda created the sitcom reality they find themselves in. A trip down memory lane for Wanda reveals that her grief over losing her parents, her brother and her significant other erupted as a burst of power that created the hex -- and Vision (Paul Bettany) within it.

"I know what you are," Agatha intones. "You're supposed to be a myth -- a being capable of spontaneous creation, and here you are, using it to make breakfast for dinner. Your children, Vision, this whole little life you've made -- this is Chaos Magic, Wanda. And that makes you The Scarlet Witch."

Ahead of the WandaVision finale, ET's Ash Crossan spoke with director Matt Shakman to break down the introduction of witches into the MCU, find out what's actually going on with Evan Peters' "Pietro" and get the story behind everyone's favorite new song, "Agatha All Along."

ET: We're left on a cliffhanger [after episode 8]. Talk to me about the significance of Agatha's talk of Chaos Magic and calling Wanda "The Scarlet Witch." What can you tell us?

Matt Shakman: Well, Wanda's had power for a long time, but it's never been defined. And there is magic in the MCU, but we haven't talked about witches before. So, episode 8 really is talking about how there are witches in this world. Agatha's one of them, and she is here to help Wanda figure out who she really is. Episode 8 was a lot about looking at Wanda's past, but it's also a lot about destiny and about what's to come.

Wanda has this vision in the Mind Stone -- Vision pun intended -- and we see the fully formed Scarlet Witch look, and it's immaculate. Can you explain what's happening here?

Episode 8 is a really interesting episode because it is about exploring the grief, the loss, the trauma. It's also about exploring love. The deep love that she has for Vision, for her parents, for her brother, all of that is in that episode, as well. But what's past is prologue, right? There are also moments of destiny implied, that all of this is a journey that she's been on that's been leading to something. And when that Mind Stone comes to her, it's coming to her for a reason.

We have to talk about "Agatha All Along," because I did not expect there to be a certified bop in this show. What's it like debuting probably the best song of 2021?

Hats off to the Lopezes, because they're geniuses, and hats off to Kathryn Hahn for singing the heck out of it -- along with some amazing backup singers -- and doing so well that she managed to overtake Bieber and The Weeknd on the iTunes charts, which made me so happy. It was a blast to put that together. We were going along and in every era, we knew we would have an "Agatha All Along" moment, so there was a lot of discussion about what those moments would be and crafting them through storyboards and sort of figuring it out.

Then we would be shooting something in the '50s and have to stop and do that "Agatha All Along" moment, which would mean turning to a much more cinematic style, breaking what we were doing and having fun with Kathryn Hahn for 45 minutes to an hour for that section. I loved every time we did that. We were always coming up with new ideas. I think my favorite was coming up with the picnic, where we pull back from Pietro and there's Hahn having fun with the grapes and the wine. The poor prop guy, Elliot, had to make that in, like, five minutes, because he had no warning. But those things were really fun and help support, I think, what is a very catchy tune. Very catchy tune.

That's one of the theories people have had since early on, being like, "Is Agnes Agatha? Could this be her?" What do you think was the earliest tell that Agnes is Agatha? Was there something in episode 1 that people might have missed?

You know, we've had this broach there pretty much the whole time. When you announce a character but you call her, "Just the nosy neighbor" and it's Kathryn Hahn, you're basically inviting the comic fans to go on a deep dive and see what they can figure out. So, speculation has run rampant around her role for a long time. We knew that we would eventually be making this big reveal, and for some, they might be slightly ahead of it -- and that's OK, as long as the reveal is a whole lot of fun, which I think the Lopezes delivered big time -- and for those of us who are not maybe as familiar with that character or haven't gone in the deep dive into the comic books, there's hopefully that Keyser Söze moment there, as well, where you're surprised. There's some beautiful scenes, I think, in episode 6, especially the one between Vision and Agnes over at the edge of town, where maybe those who thought they were on the Agatha train were thrown off a little bit by what they saw there. We did our best to continue with some red herrings in this direction along the way towards that big reveal.

It worked. We also find out that Agatha was the one that formed the Evan Peters version of Pietro -- she calls him Fietro, which I love -- let's talk about this conversation of bringing Evan Peters into the MCU in this form.

Yeah, Agatha does talk about how she was manipulating him and controlling [him]. Pulling the strings. Where that goes, there's still one episode to go, so I don't want to talk too much about that. But having Evan in this world is amazing. It was something that we talked a lot about very early on, and I'm so glad we were able to do it, that we were able to make that work. He's very special, and I think his work in the show is fantastic. Much like all the other actors, he's capable of so many different tones and styles. And I love Uncle Pietro, Uncle P. Uncle P is great.

So there's potentially more to come with whatever's going on there with the Evan Peters-Fietro thing?

Yeah, potentially.

Was there ever talk of bringing Aaron Taylor-Johnson into the mix?

Lots of conversations were had. I think this question was asked of Kevin Feige last week [at Disney+'s TCA], and that was definitely something that was discussed early on. But eventually, the decision was made to not go down that way.

You've had a lot of debuts and reveals in this show, a lot of responsibility of debuting characters -- we saw Monica Rambeau and how she gets her powers -- but which one felt like the biggest responsibility?

They were all equally big. I think Teyonah Parris has just crushed it. And her story is a parallel story with Wanda's, she's dealing with the loss of her mother, she's coming back into a very disoriented new world where she's returned from being gone. She's trying to put the pieces of her life back together. So, those stories are absolutely designed to be parallel stories, and it's why those two characters feel some sort of affinity for each other. And it's why, perhaps, Wanda brings Monica into the world to begin with.

Creating the new version of Monica, when she moves through that hex, was a really exciting moment for all of us. Teyonah just crushes it, and she had to crush it again and again and again, in a million different outfits as we put that together. This idea that she was being taken apart and remade inside this hex, this world, was a great moment for us. I think it was really fun visually. But they've all been really fun. Even just opening the door on Uncle P at the end of episode 5, as simple as that is -- it didn't involve any crazy visual effects -- it's still one of my favorite shots.

There have been a lot of the fan theories running rampant. I don't know how much you're reading them, but I just saw a really convincing one about the significance of the flowers in front of each of the houses. Are fans onto something with that?

I have to say, I'm so taken by the level of engagement from the fans. We built this show with so much love and passion and attention to detail, and that we're seeing it come back to us with so much love and passion from the fans. We share these memes and TikTok videos and everything that's coming out among the cast and crew, and we're just so blown away by the level of engagement and also the amazing creative spirit that's out there, too. I can't speak about anything in too much detail, except just to say, thank you for all the crazy, amazing stuff that you guys are coming up with.

The WandaVision finale is streaming on Friday, March 5 on Disney+.