Yarah de Silva was an eleven year old girl who lived in Avelar, Brazil. Her father was a scientist working for Positron Incorporated. Desperately wanting a puppy, but was allergic to animals, her father makes her a robot puppy. She named the dog, Digger after he dug up the entire garden when she scratched herself on a rosebush. She was saddened that Digger was deactivated by the Eighth Doctor, when Digger was trying to create weapons in order to destroy the world to keep her safe. The Doctor gave Yarah a shape-shifting alien that changes into the puppy that Yarah always dreamed of.