Penelope Platypus is a member of the Substitute Freedom Fighters who hails from Downunda. Penelope was one of several Freedom Fighter recruits chosen by Sally Acorn for a special mission meant to determine their potential. The mission resulted in the uncovering of Dr. Ivo Robotnik's Auto Automatons, a scheme that the Substitute Freedom Fighters, aided by Geoffrey St. John, were able to thwart.