I just had a weird LBT idea. Granted, I don’t like the idea of a “bad” Chomper, but this one is workable.
Suppose that Chomper stays in the Great Valley for years and ends up saving loads of Great Valley residents, perhaps from a fire. However, eventually he gets too big and does end up having to eat Leaf Eaters to live. However, the Great Valley, in gratitude for him saving them, lets him stay provided:
1.) He doesn’t hunt where they can see it or know about it (i.e. no blood on his claws or bones left around, etc. where it would freak out the residents.)
2.) He doesn’t hunt them or anyone they know (so Tippy’s herd, Bron’s herd, and Ali’s herd would be off limits.)
3.) He doesn’t hunt children.
4.) He gets it over with as quickly as he can. (i.e. no suffering for the prey)
So he follows the rules, but eventually some Leaf Eaters find out that the Great Valley is sheltering a Sharptooth and lay siege to it for revenge.