Mums is shown to be very egocentric and grumpy. He only cares for himself and becomes very annoyed when people disturb his rest. His selfishness goes so far, that he is willing to endanger the world for his own desires. At first, he makes frequent attempts to eat the Beetleborg children, who are the only ones able to defeat the Magnavores and later Crustaceans. Later, he even strikes up a deal with the Crustaceans, giving them the Astral Sword in return for them leaving Hillhurst alone. It does not occur to him that doing so would endanger the entire world, including Hillhurst.