This is the kind of thing that goes on under Baroness Vannett’s back porch all the time, in my Bell Mountain books. Wait’ll this cat tries to get a job at any farm. “You play with the rats? Get lost!”
But I’ve had rats as pets, and mine were wonderful–affectionate, fun-loving, and smart (even if they were a little hard on each other). People who muttered “Yeeeew!” when I brought one of my rats into the vet’s waiting room wound up petting and talking baby-talk to it.
And I did have a cat named Henry who peacefully sniffed at my pet mice and never tried to knock the lid off their aquarium. But I think that was because what he really wanted was my baby fence lizards. Oh, he wanted them so badly! But he didn’t get ’em.