Second child and only son of Crown Prince Rhaegar Targaryen and Princess Elia Martell of Dorne, born at the Red Keep in 281 AC and named for the Conqueror who had bound the Seven Kingdoms together with fire and blood. His sister Rhaenys, two years his elder, doted on him from his cradle, and his father, looking down upon him in his nursery, was heard to tell the Lady Elia that he is the prince that was promised, and his is the song of ice and fire, then turned to his harp and spoke of needing one more, for the dragon must have three heads. Before the babe had taken his first steps Rhaegar lay slain in the bloody waters of the Trident, struck down by the warhammer of Robert Baratheon, and Aerys II called his goodsister and her children to the Red Keep that they might be hostages against the Dornish.
When the Lannister host came treacherously through the gates of King's Landing at the end of Robert's Rebellion, Lord Tywin set Ser Amory Lorch and Ser Gregor Clegane to the royal nursery in Maegor's Holdfast. Lorch slit Princess Rhaenys from belly to throat beneath her father's bed; the Mountain tore the infant Aegon from his mother's breast and dashed his head against a wall, then raped Elia upon her son's blood before splitting her skull with his gauntleted hand. The small ruined corpses were wrapped in crimson Lannister cloaks and laid at Lord Tywin's feet, then carried into the throne room and cast at the boots of King Robert as the first gift of his new reign; the bodies were so disfigured that none save the killers could swear whose they had been, a doubt that would in time be turned to the Targaryens' use. Across the narrow sea in Pentos, a silver-haired youth dyed blue and called Young Griff was raised under the wing of the eunuch Varys and the cheesemonger Illyrio Mopatis, presented at last to Tyrion Lannister aboard the Shy Maid on the Rhoyne as the prince smuggled from the holdfast in another babe's swaddling, and brought back to Westeros in a Golden Company landing to claim by sword and fire the Iron Throne his father had been promised.