Avengers: Endgame's five-year time-jump saw Scott Lang reunite with his daughter, Cassie, albeit as a teenager rather than a child. Emma Fuhrmann replaced Abby Ryder Fortson as the character but was unceremoniously ditched by filmmaker Peyton Reed for Ant-Man and The Wasp: Quantumania.
Fuhrmann's role was small enough so that it didn't serve as a distraction, while her replacement, Kathryn Newton, is undeniably more experienced after starring in the likes of Supernatural, Detective Pikachu, and Freaky.
Despite that, Newton didn't receive overly positive reviews for her performance as Cassie, a character who was somewhat underwritten in the threequel.
Talking during the Director's Commentary for Ant-Man and The Wasp: Quantumania (via CBR), Reed talked candidly about the decision to replace Fuhrmann. "We've just introduced our now 18-year-old Cassie Lang. Kathryn Newton, of course, an actor who I have admired for a long time."
"And when we were talking about Cassie in this movie, she's aged five years since the events of Ant-Man and The Wasp," he continued. "And I wanted someone in that role who could really hang with Paul Rudd and sort of not be left in the dust."
It seems a little harsh to suggest that Fuhrmann couldn't "hang" with the actor, but it seems he might not have had the input he wanted when the Russo Brothers chose a new actress to play Cassie in the MCU.
Reed later added, "She's gotta be sharp, and quick, and funny. And also, [Newton] is an athlete. She's a world-class golfer. She has the physicality for the role."
Cassie suited up in Ant-Man and The Wasp: Quantumania and controlled her newfound abilities with ease. It's unclear what the future holds in store for the character moving forward, but with no plans for the Young Avengers to assemble, she's likely to remain a supporting character for now.