Unalaq became the chief of both the Northern and Southern Water Tribes after his brother, Tonraq, was banished for actions that nearly led to the destruction of the Northern Water Tribe. As a result, their father made Unalaq the new heir. When he later became chief, he also gained territorial control over the closed spirit portals, putting him in a unique position to secure the entrances and carry out his eventual goal of releasing Vaatu and fusing with him to become a Dark Avatar.