The term 'Mouse Cousin' is a reference to the rodent known as the RAT. Rats are related to mice, and are often found in urban areas. They are typically brown or black in color, and have long tails. Rats are omnivorous, meaning they eat both plants and animals. They are also known to be carriers of various diseases, such as the bubonic plague. Rats are considered pests by many people, and are often seen as a sign of uncleanliness.