Daemon Targaryen was the younger brother of King Viserys I and, by most accounts the Citadel is willing to stand behind, the most gifted swordsman of his generation — a fact he never let the court forget. He carried Dark Sister, the Valyrian blade of his ancestor Visenya, and rode Caraxes, a dragon the smallfolk named the Blood Wyrm for a temper that suited its rider rather too well.
He made himself Prince of the Stepstones by conquest before he was thirty, then lost the title, then took it back, in a private war against the Triarchy that the crown alternately funded and disowned depending on how the fighting was going. Two marriages followed — first to Rhea Royce of Runestone, a match neither party pretended to want, and then, after Rhea's death and his own long courtship of his niece Rhaenyra, to Rhaenyra herself, uniting the throne's heir with its most dangerous claimant to the throne in one household.
When Viserys died in 129 AC and the throne split between Rhaenyra and her half-brother Aegon II, Daemon became the Blacks' sword rather than their diplomat, which suited him. He died on the twenty-second day of the fifth month of 130 AC above the Gods Eye, locked in single combat with his nephew Aemond Targaryen — Caraxes gripped in Vhagar's jaws, Daemon's blade finding Aemond's eye, both riders and both dragons falling together into the lake. Rhaenyra outlived him by less than half a year.