Due to numerous experiments upon her mind, her psyche is incredibly shattered, and she often has trouble remembering things as a result. She also speaks to her stuffed doll, Mr. Bear, and looks up to her older sister Tabitha, though she claims Mr. Bear doesn't like her.
Penny was engineered by Caulder as one of his clones and was experimented on by the scientist numerous times, shattering her sanity and causing her to develop an odd fixation on explosions.
Penny first appeared after the defeat of The Beast, though she did not reappear until after the defeat of Admiral Greyfield. Along with her siblings, she was given the Great Owl and threatened to use it unless Isabella was turned over to them.
Later, when Will boarded the plane in an attempt to rescue Isabella, Caulder ordered her to crash. Isabella, however, talked her out of it. Penny later helped the 12th Battalion establish the village of New Hope, and was seen with it a year later.
Penny talked with Will and failed to remember him at first due to her short-term memory loss. She also mentioned how both Caulder and Cyrus had gone "BOOM" but hesitated to say anything about Tabitha, suggesting that her older sister was still alive, and eerily states that she and her siblings are all "one big system".
- Since Isabella is also a clone daughter of Caulder, Penny could be considered her sister.
- She is the only CO in Advance Wars: Days of Ruin to possess a non-CO Power ability that affects all units outside of her CO zone.