In "Little Nicky," the ruler of darkness refuses to relinquish his throne to any of his three sons. As a result, the two strongest siblings flee to Earth to establish their own dominion, causing the portal that channels sinful souls to Hell to shut down. This leads to Satan's decline. To rectify the situation, he sends his most fragile yet cherished son, Little Nicky, to Earth with the task of bringing his rebellious brothers back to Hell.