Jason Lannister is the Lord of Lannisport and the sister of Ellyn Lannister. He is the third child of Tyrek Lannister and his wife, Joanna Crakehall, and was the brother of Hyle Lannister. He briefly served as Lord Paramount of the Westerlands before forced to abdicate by Tytos Kenning. In his name, Ellyn was named Lord Paramount, and Jason worked to restore order and bring her support, culminating in the events of 364 AC.