The common-born son of a steward in service to Lord Dondarrion of Blackhaven, who rose by the strength of his arm and the favor of King Viserys I to a white cloak in the Kingsguard. Tall, dark, and comely, he took the tourney prize at Maidenpool in 111 AC by unhorsing Prince Daemon Targaryen with a morningstar, and he wore Princess Rhaenyra's favor upon his sleeve, becoming her sworn shield in the years before her first marriage. Of what passed between them the singers tell different songs (some that he begged her to flee with him to the Free Cities and was refused for honor, others that she sought to lie with him and he refused her for honor), but he turned bitter against his princess and gave his loyalty thereafter to Queen Alicent Hightower and her sons, plotting at the green council that crowned Prince Aegon king of Westeros over his half-sister's claim.
In the war that followed he placed the iron crown of Aegon the Conqueror upon Aegon II's head with his own hands in the Dragonpit, and the realm thereafter called him the Kingmaker. Named Lord Commander of the Kingsguard and Hand of the King to the new king, he led the green armies through the riverlands, slaying lords and burning fields, until in 130 AC he was caught upon a low hill by Red Robb Rivers and the river lords at a place that came to be called the Butcher's Ball. There he refused to surrender or to flee, set his white cloak aside, and bid his men ride down with him into the storm of arrows that took his life and broke the host of the greens.