By the end of "Avatar," Jake and Neytiri manage to overcome their differences and agree to start a life together. By the time "The Way of Water" rolls around, they're still together roughly 14 years later, and they got a few kids out of the deal. There's their oldest son Neteyam (Jamie Flatters), middle child Lo'ak (Britain Dalton), and youngest Tuk (Trinity Jo-Li Bliss). Based on their personalities throughout "The Way of Water," it's safe to say that Neteyam and Lo'ak are relatively close in age as teenagers, especially seeing how Jake trusts them to go on missions with him against the Sky People. Meanwhile, Tuk is a bit younger, with her being about eight years of age, during the main events of the film.
Jake and Neytiri also have an adopted daughter in the form of Kiri (Sigourney Weaver). Weaver appeared in the first film as Dr. Grace Augustine, but she died during the conflict between the Na'vi and the humans. When Dr. Augustine died, it rendered her avatar body brain-dead, and it just so happened to be pregnant with Kiri. She's about 14 years old in "The Way of Water," so her birth most likely occurred shortly after the events of "Avatar."
"The Way of Water" dedicates a ton of screentime to these four children, and it's clear they are going to have ample development should the series continue with more movies.
