Si and Am are a sinister pair of cats who use the love they gain from Aunt Sarah to get others into a large amount of trouble. The cats are sneaky and love to cause trouble and make messes for their own amusement. It is indicated that they are spoiled and take advantage of Aunt Sarah's coddling, seeing her as a protector and not a beloved owner. According to the novelization, whilst the siamese sisters love getting dogs in trouble, they draw the line at getting another pet killed.