Mousie quickly resumed his macho attitude, doing battle with Mr. Bear and various pieces of crumpled paper and even biting the hand that feeds him. As pictured above, he seems to be saying, "Surely you jest" at the thought of meekly obeying anybody else's rules for his conduct.
How did such a brute come to be named Mousie?
Here's why. Up until the time he took a liking to this writer, he was an underweight, sickly creature, quiet as a mouse. Since leaving the feral life behind, he has filled out, grown big muscles and asserted his claim as lord of all he surveys. When not imperiling my house plants or testing his new fangs on important documents, he will occasionally let himself to be petted or spoken to in terms of endearment before resuming his brawling.
No new name has emerged to replace "Mousie." Someone suggested "Moosie." But he really no longer cares what he is called, because now he is calling the shots.