Sigourney Weaver, 73, talks teen character in 'Avatar 2': Older actors are 'extraordinary'

Before Sigourney Weaver could return to Pandora, she had to go back to school. 

In "Avatar: The Way of Water" (now in theaters), a sequel to James Cameron's 2009 sci-fi adventure, the three-time Oscar-nominated actress plays Kiri, a 14-year-old Na'vi alien. Kiri is the daughter of Dr. Grace Augustine, Weaver's scientist character, who was killed in the first movie. After Grace's death, Kiri was adopted as a baby by Jake Sully (Sam Worthington) and Neytiri (Zoe Saldaña).

To prepare to play a teenager, Weaver sat in on classes at New York's famed LaGuardia High School for the Performing Arts, where she observed a wide range of adolescent behaviors. 

"I was just sitting on the side (of the classroom) listening to the pitch of the voices: everything from a childlike voice to an adult voice," Weaver explains. She never participated in class exercises, though: To the young acting students, "I was just another actor. They had their own stuff to do." 

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When "Avatar 2" picks up, Kiri is searching for answers about her father's identity while trying to unravel why she's different from other Na'vi kids her age. Over the course of the film, she learns to harness powers that are tied to the natural world and Eywa, the life force of the planet Pandora. 

Cameron approached Weaver, 73, about the new character way back in 2010. "I wanted to get the band back together," says Cameron, who first directed Weaver in 1986's "Aliens." 

Together, they "discussed the idea of creating this girl who was more at home in the forest than she was with people, and had a connection to plants and animals that she didn't quite understand," Weaver says. "Even before (Cameron) wrote it, he said to me: 'Nobody else knows this about you, but I know that you are 14 at heart, anyway. You're so mature, and yet you're always clowning around, so I have no doubt that you can do this.'" 

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Along with the rest of the "Avatar 2" cast, Weaver trained in breath-holding to shoot the film's aquatic motion-capture sequences. She also joined her younger co-stars in learning underwater sign language and parkour for scenes of Na'vi teens running along tree boughs or racing to the tops of floating mountains. 

"I was determined to be able to do everything they did. I didn't want anyone to say, 'She's kind of an old lady,'" Weaver says. "We all had to be really fit, and parkour is a very good way of getting there."

Other cast members participated in knife-fighting and archery lessons, but "Kiri is not a fighter," Weaver adds. "She's a very gentle person. She can be filled with rage, and she's very sensitive to injustice and cruelty, but she doesn't use weapons. She has other powers." 

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For Weaver, the chance to be a kid again – even just on screen – was liberating. But rather than giving a middle finger to Hollywood ageism, she considers the role a "celebration" of what motion-capture technology has made possible. 

Like animated films, "it frees the actor from certain longtime conventions that you have to play your own age group," Weaver says. "It just allows you to play anything and flow into any kind of form."  

Over the course of her five-decade career, Weaver has created iconic movie characters such as Ellen Ripley in the "Alien" franchise and Dana Barrett in the "Ghostbusters" films. Her secret to longevity? Not letting herself get pigeonholed. 

"I realized early on that people really didn't know what to do with me, partially because of my height," says Weaver, who is about 6 feet tall. "After Ripley, I was sent (scripts for) 100 strong women and after 'The Ice Storm,' I was sent 100 neurotic women. I could tell right away that it was up to me to not repeat myself: I wanted to do a comedy and then a drama; play the queen and then the maid. So I just did it for myself. I wanted to direct my own career, which I was able to do. 

"A lot of us older actors, the range of what we do is so extraordinary. So I hope that Hollywood has gotten that message – whoever Hollywood is now." 

Contributing: Marco della Cava 

This article originally appeared on USA TODAY: 'Avatar: The Way of Water': Sigourney Weaver on ageism, Kiri’s powers