Per the title, I think it would be really cool for the ambience of the game and a sense of actually affecting the world with our actions, if after being freed or liberated the animals from the fable would then start patrolling and guarding an area designated as their "territory". Maybe have them path ocassionally into insignificant patrols of Ode so you can jump in to fight alongside them.
Just imagine, you're wandering through the wevetwood and you find Bromius scratching his back on a tree, or quietly staring at a little sprout thats started to grow out of the soil
Orengall teaching her pups to hunt
Garren Rood just being regal as all getout and having his Princess Mononoke silhouette moment.
It doesn't even need to be dynamic or that complicated, I'd be happy to just have an NPC wandering around and a sense of the world returning to its old self in our wake and these magnificent creatures we're forming pacts with being there because of us.