Penny is the youngest child of Dr. Caulder, whose numerous experiments on her have left her mind permanently shattered. It was stated by Dr. Caulder that her mind was altered to allow her to control an entire battlefield singlehandedly. She has a close bond to her teddy bear, "Mr. Bear". She looks up to her older sister Tabitha. Penny is quite childish and has trouble understanding things. This and her trouble remembering things are most likely caused by the experiments that were done on her.