I'm rereading Redwall by Brian Jacques. If you didn't grow up reading this series, a brief recap looks like:
bunch of anthropomorphic woodland creatures living in their abbey, Redwall. In this story, the evil sea rat Cluny and his horde decide they want to rule Redwall, since it's a very peaceful, plentiful spot.
The mice and squirrels and hedgehogs etc have to defend their home.

These were some of my favorite books as a kid. They still hold up pretty well. But the fascinating thing about them is that the peaceful, brave, kind creatures are the woodland animals I described above: mice, squirrels, voles, moles, hedgehogs and rabbits. The evil doers are always rats (specifically sea rats), weasels, stoats, etc.

There is clear delineation between "animals we like and want to associate ourselves with" and "animals that we mistrust or dislike and associate with evil, greed, cruelty and stupidity."

What is the moral difference between a mouse and a rat? How did certain animals get singled out as baddies?
And why is it always weasels and stoats?!?