‘Quantumania’ star Kathryn Newton schools Seth Meyers on channelling her inner Cassie Lang

While Paul Rudd’s Ant-Man (aka Scott Lang) might never completely grow up inside Marvel's movie playground, the same can’t be said for his daughter Cassie — a kid who survived Thanos’ fateful blip here on Earth and kept right on sprouting as Scott spent her key formative years kicking around inside the tiny Quantum Realm.

Now a brainy 18-year-old ready to don a size-shrinking Hank Pym suit of her own, Cassie’s set to spend some quality MCU time with her dad in the diminutive world of the upcoming Ant-Man and the Wasp: Quantumania. Kathryn Newton — an acting veteran of The CW’s Supernatural as well as Pokémon Detective Pikachu (2019) and horror comedy hit Freaky (2020) — graduates to Cassie’s older onscreen role for the new film, after younger versions were portrayed by Abby Ryder Fortson (in both 2015's Ant-Man and 2018’s Ant-Man and the Wasp), and later in Avengers: Endgame by Emma Fuhrmann (as the teen who answers the door when Scott finally makes it back home).

RELATED: Paul Rudd tells Jimmy Fallon that ‘Quantumania’ set had to be shut down over a bunch of manure

Newton’s all about fully embracing the part, as it turns out, confessing on NBC’s Late Night with Seth Meyers that putting on Hank’s powered-up Ant Suit has had a funny way of bringing out Newton’s eager-to-please inner superhero — even when she’s not, strictly speaking, supposed to be in character.

Check it out:

Sporting pulled back hair and a sleek sequined jumpsuit for her Late Night appearance, Newton joked that her civilian duds are just another way of channeling her inner Cassie — or, as she put it, giving her own spin to the same method-acting approach of her Quantumania costar and main movie baddie, Jonathan Majors (Kang the Conqueror).

“Cassie Lang is a genius, you know?” Newton teased. “After I finished the movie, I didn’t have job; I was very bored. So I signed up for a physics class at UCLA, and I did that, and I got an ‘A,’ thank you! So we’re the same [Cassie and I], once again…I’m just really ‘method’ — just like Jonathan Majors!”

RELATED: David Harbour explains to Seth Meyers the parenting tactic he learned from 'cop shows'

Quantumania puts Scott on a family-minded mission to make up for the tons of time he lost watching Cassie grow up, after Thanos and the Infinity Gauntlet (not to mention Scott’s extended Quantum Realm tour) stole away years of quality father-daughter time. That need to play catch-up is a two-way street, said Newton, who described her suit-wearing older version of Cassie as a budding superhero...but one who still carries a young kid’s craving to make a good impression.

“Everyone looked at me like it was really ‘me,’” she said of her on-set time in the Ant Suit. “Like, they think that’s who you are all of a sudden when you wear the supersuit — and I promise you, I fall just the same in that thing as I do in this. I fell a lot. I’m a tripper, I fall just like Cassie! Like, I was trying to figure out how to be in a Marvel movie and impress everybody — and she’s a little young hero trying to impress her dad. We’re very similar!”

Cassie and Scott won’t be the only two humans downsizing to take on Kang in the Quantum Realm, with Quantumania also set to return Michael Douglas (Hank Pym), Michelle Pfeiffer (Janet van Dyne), and Evangeline Lilly (Hope van Dyne aka the Wasp) in the official movie kickoff for Phase 5 of the Marvel Cinematic Universe. Catch Newton in her MCU debut starting Feb. 17, when Ant-Man and the Wasp: Quantumania buzzes into theaters everywhere.

Stream all the Late Night with Seth Meyers laughs right now on Peacock.