Warning: This post contains spoilers for Avatar: The Way of Water.
There’s a quite a long time between the original Avatar and its first sequel. How long? Long enough that Jake and Neytiri have teenage children. (One of them is 18. Perhaps Na’vi age quicker than humans.) But while most of the film is very impressive CGI, there is a degree of realism there. Cameron really did have his actors, in mo-cap doodads, hold their breath under water for Guinness-breaking lengths of time. He also insisted on casting real kids as the Na’vi kids, though he was worried that by doing so they’d succumb to something he called “the Stranger Things effect.”
What is “the Stranger Things effect”? It’s a term coined by Cameron, made public during an Entertainment Weekly interview, in which kid actors suddenly age a ton between seasons of films, as happened to the gang on the Netflix blockbuster (which Cameron adores). He didn’t want that to happen to his young charges, among them Trinity Jo-Li Bliss (7 when she was cast as Tuk, now 13) or Jack Champion (12 when cast as Spider, 18 now). He worried that if he spent too much time in between shooting sequels, they’d wind up “growing like a weed.”
Had he done that, Cameron said, “you get — and I love Stranger Things — but you get the Stranger Things effect where they’re supposed to still be in high school [but] they look like they’re 27.” He added, “You know, I love the show. It’s okay, we’ll suspend disbelief. We like the characters, but, you know.”
You could argue that CGI could have taken care of all that. But Cameron doesn’t do things the easy way. Perhaps it’s all part of the plan, and the fourth sequel will have Tuk and Spider be much older (provided none of them are killed by Stephen Lang’s now-Na’vi Col. Quaritch). Then again, he did cast Sigourney Weaver as a teenager.