Harmund the II spent his youth as a ward of the Lannisters at Casterly Rock. Once he became the King of the Iron Islands, Harmund married Lelia, the daughter of the King in the Rock. Their children were raised to follow the Faith of the Seven.
When Harmund II died, he was succeeded by his eldest son with Lelia, Harmund III Hoare. He was opposed by the Drowned Men due to his desire to outlaw reaving, salt wives, and thralls. A Drowned Man called the Shrike led a quick and successful rebellion, crowning another of Lelia's sons, Hagon Hoare, who restored traditional Ironborn practices.
Hagon became known as Hagon the Heartless as he gave his brother and mother over to the rebels to be mutilated. The Shrike blamed Lelia for turning her husband and son away from the Drowned God. Lelia's lips, ears, eyelids and tongue were removed, and she was then returned to Casterly Rock
The then-King of the Rock, Lelia's nephew, was outraged, and declared a war of retaliation on Hagon. Ser Aubrey Crakehall, a Lannister commander, would defeat Hagon and capture him. Before being hanged, Hagon was mutilated in the same way that Lelia was.