I'm trying to recall a story I read in the early-to-mid 80s. It was a school library book and probably old at the time. I don't recall any details of the cover. I do not believe it is Lost Race of Mars.
The protagonist is a teenager on Mars. A new authority figure comes into his life, either a teacher or an administrator of some sort, someone who is not flexible or patient with the customs of the people on Mars. For example, teenagers routinely painted their helmets for individuality - I believe the protagonist painted his like a tiger - and the authority figure ordered them to remove the paint.
Protagonist has a "pet" of local Martian fauna. At one point in the story, protagonist discovers that their "pet" is in fact the immature version of the adult Martian lifeform, something that had not been understood before that.
The overall arc of the story is Protagonist's rebellion against the new Authority, which I believe succeeded in the end, perhaps helped by his new understanding of or with the Martian natives.