More on the Prototype Factory. The Rat has a mixed history. He was meant to be a poster boy of the zodiac. But he was too smart for his own good. Smart can mean bright. Smart can mean cunning, which is no good.
An ancient folk story tells that the Cat and the Rat were the worst swimmers in the animal kingdom. But though they were lousy swimmers, both were quite intelligent.
Once, Buddha called a meeting of all the animals. He had decreed that the years on the calendar would be named after each animal in the order in which they arrived.
To get there, the Cat and the Rat realized they had to cross a river, alas. Cat and Rat figured that the fastest way to get across that river was to hop on the back of the Ox. Being naïve and good-natured, Ox agreed that the two could get a ride on his back.
Midway across the river, Rat pushed Cat into the water and Cat drowned. As soon as Ox neared the other side of the river, Rat jumped ahead and reached the shore first. So he was able to claim the first place in the competition in the zodiac.
But the Rat could not remove the stink of his dastardly deed. He remained all his earthly life an unsavory creature, sneaking into pantries to taste goodies never meant for him. When rat traps and poisons were invented to thwart him, Rat was reduced to scrounging in garbage cans along with the cockroaches and other vermin.