'WandaVision's Teyonah Parris & Kathryn Hahn on Their Mysterious Characters (VIDEO)

Disney+'s buzzy new Marvel series WandaVision unloads plenty of big questions onto viewers, and while we eagerly watch for clues into the larger mystery at play, there are two particular wildcards we'll be keeping tabs on as the show progresses: Agnes (Kathryn Hahn), Wanda and Vision's neighbor who seems to be up to something, and Monica Rambeau (Teyonah Parris, who will reprise her WandaVision role for Captain Marvel 2).

We chatted with the two stars ahead of the WandaVision premiere to get their take on what's to come. Rambeau, who has grown up since viewers first saw her in Captain Marvel as the daughter of Carol Danvers' (Brie Larson) oldest friend, is now an agent in the cosmic organization S.W.O.R.D. who somehow finds herself ejected into the sitcom universe.

"We start to dig deep into who [Monica] is as a person, what she's been going through, her current aspirations," Parris says.

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Plus, Bettany says he thought he was getting fired from the MCU before they offered him the show of a lifetime.

She also discusses being a part of the audience for the live taping of the series' first episode — Parris' first onscreen moment isn't until the second installment — which introduces the mysterious Agnes (Hahn).

Hahn describes Agnes as "nosy, definitely an oversharer, definitely a gossip." At times, she's a thorn in Wanda and Vision's sides, though she overall strives to be a friend. "For a couple that is new to town, Wanda and Vision, who just want to try to blend in and fit in, she doesn't give them a lot of space," Hahn says.

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'The journey for both of them,' says Bettany, 'is finding out what the hell is going on.'

Perhaps Agnes has a darker reason to keep an extra close watch on the Avengers duo? Some fans have surmised that Agnes is actually Marvel comics' witch Agatha, who has some sinister connections, but for now, Hahn is mum as to what's truly going on with her character.

"As anything in this show, there are so many layers at all times, for every character and every person," she says. "You're going to get surprised."

Check out the full video interview above.

WandaVision, Series Premiere, Friday, January 15, Disney+