The Cleganes hold a keep as sworn knights. The first Clegane was raised to knighthood after saving Lord Tytos Lannister from a mountain lioness at the cost of a leg and three hunting hounds. His grandson Ser Gregor, a huge and fierce knight called the Mountain that Rides, now rules the keep. He was a knight of 17 years when he took part in the Sack of King’s Landing, where it’s said that he killed Prince Aegon and raped Princess Elia before putting her to the sword.
Ser Gregor’s father died in a hunting accident and the death of his sister was under strange circumstances. On his father’s death, Gregor’s young brother Sandor Clegane left their lands never to return, swearing his sword to the Lannisters and becoming sworn shield to Prince Joffrey. Ser Gregor has no children, although he has had two wives and is preparing to marry a third.