Walleo is the lesser demonic cousin of Weegee. He was born on the same Date like his Brother Malleo, and lives inside Scrooge Mcduck's Bank WHY? Because there's Money.
He was born when Washesh was having a child, but some Malleo DNA got into the womb and made the child half Malleo, half Waweegee. Walleo was named when Papa Waweegee remembered his old enemy, Wario, so he named his son Walleo.
He is in constant agony just like Malleo is when he lives with Waweegee since he threatens him with cooking Spaghetti for him and giving him the death glare. Waweegee would later regret his actions and switch roles with Walleo treating him with respect since they held a special hatred towards Weegee and Malleo.