Mine was Venus Boy. It was about a kid who lived on Venus, where everyone has to wear armor whenever they go outside because of the arrow-birds, who dive on you and stab you with their beaks. The kid has a pet bear, and bears on Venus can talk and have valuable claws. So the kid learns to talk the bear’s language, and puts nail polish on the bear’s claws, because when Venus bears are young their claws are black, but when they grow up their claws turn blue and are used in making plastic.
Now it is all flooding back. There is a passage where the kid and an adult are out on Venus without their armor, but all the animals on Venus speak the bear language, so the kid is chanting over and over, “Friend-pet, friend-pet, bother us not!” “Friend-pet” is what the bear calls the kid. Then at the end they find out the bears shed their claws automatically, so they no longer have to kill the bears to make plastic.
Like you, I should re-read it to see if it holds up.
It’s like romance - you never forget your first.