As the former rat-turned-Penny was fucking the man that gave her humanity, thoughts were going through her head. Not just thoughts of pleasure as Adam's dick was forcing its way into her pussy, but thoughts on how to bring down humanity. She was clever enough to realize that the ring on Adam's finger was the reason she was human and knew she needed to get it. As Adam reached orgasm, the new Penny made her move. She reached for his hand and slipped the ring off. As the ring hit the floor, Adam in his orgasmic bliss couldn't move as he cummed all over the new Penny and the bedsheets as Penny got off her lover and dove for the ring. She reached it and put it on her finger.
Just as Adam was about to grab her, she said, "Be a rat!"
Soon Adam felt pain in his stomach as he shrank down. Soon his cumcovered cock shrank down to that of a mere rat dick and soon he was a rodent. Adam ran under the bed, joining the old Penny who had taken cover there as well.
The new Penny looked under the bed at the two new rats. "Well aren't you the cutest thing. To think Penny that you had this gorgeous body and wasted it by being a dumb bitch. And Adam, just think your little cock there use to be huge and inside of me. Now you two will live the rest of your lives fucking in the sewers. Now, I'm going to go change humanity....for the better."
The new Penny got up found her clothes, and changed into them. As she left the house, she wondered how she would start her changing of humanity. Maybe she'll change people into rats, or even better gnats! Maybe she'll change some animals into humans to help lead an army of former animals. In any event, she knew humans were no longer the top of the food chain. She was.