 When Lord Eddard "Ned" Stark, Robert's closest friend and chief advisor, discovers that Joffrey and his siblings are the product of incest between Cersei and her twin brother Ser Jaime "The Kingslayer" Lannister, Eddard attempts to unseat Joffrey, but is betrayed and executed for treason.In response, Robert's brothers Stannis and Renly both lay separate claims to the throne.During this period of instability, two of the Seven Kingdoms of Westeros attempt to become independent from the Iron Throne