It has an ecosystem of 35+ different species of predators and prey that all interact within and without their species independent of you, can adapt to changes in the environment and the behavior of other species, whose behavior is depending on their own dynamic personality and body types, with some species that can work together in packs (completely with alphas that command the others)
The way Trico is supposed to become more friendly to you if you're nice to it? Every species has that, for every other individual animal and the player, and it can shift depending on your actions. Be nice, save an animal from predators, feed it, etc., and it could become an ally that protects you and doesn't act aggressive, even one of your natural predator. One species is intelligent and roams in packs, playing with each other and sharing tools, and can spread one's feeling about you to the entirety of the pack, so help them out and they'll eventually let you roam with their pack rather than being nervous and aggressive around you.
