Why Sigourney Weaver Calls Working With James Cameron on Avatar the Perfect Job for an Actor

Avatar has always saved a little mystery for Kiri, and Fire and Ash is where that simmering question mark finally takes center stage. Sigourney Weaver is back playing Jake and Neytiri's most unusual kid, and the film digs straight into the thing we all suspected: her connection to Eywa is not just a vibe, it's the point.

Quick refresher: who (and what) Kiri is

• Kiri was born from Dr. Grace Augustine's Avatar body. Grace, of course, was Weaver's character in the first film.
• After Grace died, Kiri was adopted by Jake Sully (Sam Worthington) and Neytiri (Zoe Saldana) and raised with their children.
• She's a teenager here — yes, Weaver is playing a 14-year-old again — and she has gifts that go beyond the usual Na'vi skill set: she can communicate with other species and occasionally do things that feel like, well, miracles.
• She still doesn't know who her father is, which weighs on her even as the bigger stuff hits.

Fire and Ash pushes Kiri into the deep end

Weaver describes Kiri as a kid who would rather just be a kid — until the story forces her hand. When everything goes sideways, Kiri has to stop asking why she is the way she is and start using it. Weaver says the film tracks that power taking hold of Kiri, changing her, and honestly educating her. You see it build scene by scene.

"We're also not necessarily working in continuity," Weaver told me. "So Kiri... has to step up... 'All right, I'll never understand it, but I've just got to do what I have to do.'"

That 'not in continuity' note isn't a plot spoiler; it's how they work. Cameron's process is less about marching through a rigid, linear plan and more about finding the scene in the moment. The emotional throughline snaps into place during performance, not in a spreadsheet.

How Weaver plays a teenager again (and why it works)

On the performance-capture stage — the Volume — Weaver does her homework and then gets out of her own way. She talks about Kiri as something instinctual: part human girl, part creature of Pandora, and she lets that animal side steer once the cameras roll.

"I do a lot of preparation ahead of time, but when I walk into the Volume, I sort of go, 'Okay, Kiri, take it away.' My mind is saying, 'You're not this,' and my instrument is saying, 'Let's go!'"

Yes, Weaver and Cameron are back at it like it's 1986 all over again. They've been doing this since Aliens, and that shorthand shows. Fire and Ash was shot alongside The Way of Water — parts of two and three went down together — and Cameron basically told her, with a grin, I hope you can do this. Casting someone her age to play 14 is a swing, but they both lean into it. Weaver jokes that emotionally, she can meet Kiri where she lives. Cameron clearly saw something in her that helped shape who Kiri became.

Cameron, right there in the trenches

Weaver says Cameron isn't hiding in video village watching from a tent. He's on the floor with the actors, figuring it out in real time. He doesn't hand them the map so much as go hiking with them. For Kiri, that often means exploring how she makes sense of a world that doesn't always make sense back. And crucially, he gives the cast space to try things — to fail, to find it, to go again. For an actor, that's a gift, and Weaver calls it a dream setup.

Avatar: Fire and Ash opens in theaters December 19. Kiri's not just along for the ride anymore — she's driving.