The Story of a Girl and Her Wonderful Pet! For many children, the experience of bonding with and loving a first pet is an unforgettable time in their lives. Millie and Cupcake is the charming and educational story of a girl and her companion animal … a different animal than many kids think of when choosing a pet. Cupcake is a rat, and readers will be enchanted as they learn what rats are really like: clean, loving, highly intelligent, trainable personalities who add immeasurable value to people’s lives. Follow along with Millie as she learns how to take care of her sociable, curious, and affectionate best friend.