Unlike even-tempered, friendly, and nice Aku Aku, Uka Uka is a bad-tempered, diabolical, and psychopathic villain with an inflated ego, believing that he is superior to the point that he often refers to himself as "The Great Uka Uka" in earlier games, though Doctor Neo Cortex and Doctor Nefarious Tropy have also referred to him similarly. Despite this, he is capable of rare generosity, namely when he spares Cortex's life after Cortex inadvertently sets him free from his temple prison by the ruins of the doctor's space station. In contrast, he seems to respect Nefarious Tropy for his greater relative competence. Uka Uka largely looks down on his older brother Aku Aku, whom he sees as feeble. It is implied in Crash of the Titans that he has fallen into a "shame spiral" due to his constant losses and that an earlier depression led to him engaging in bulimia. It is also claimed that he is extremely self-conscious about his lack of a body.