Well, ok, I guess I don't have to pulverize you about the rats, now. (*salute to the memories of Sparky and Fieval*) I was so distressed in book 3 about that about-turn with Scabbers: true, he was never any great paragon of rodent virtue, but at least he was a semi-positive protrayal of a rat in children's fiction. And then he had to turn out to be an evil *human*! I don't know which is worse!
But I agree with your idea about corresponding animal totems to animagi...animagusses...shoot, where's a plural when you need one? I need to brush up on my Harry Potter--once an animagus has developed a particular animal they turn into, can they turn into other animals? Or do you only get one?