Drogon is the black dragon of Daenerys Targaryen, hatched in 299 AC from a petrified egg laid upon the funeral pyre of Khal Drogo in the Dothraki sea, and named for the dead khal. He was the largest of the three hatchlings and has remained so, black-scaled and slashed with scarlet, his horns and spinal plates blood red, his eyes like coals; some among Daenerys's followers named him Balerion come again, though the queen would not give him a dead dragon's name. He is also the fiercest and wildest of the three, and the hardest for her to rein.
It was Drogon who burned the heart of the House of the Undying in Qarth, and Drogon who loosed his flame in the face of Kraznys mo Nakloz at Astapor when the queen said "Dracarys". After a Meereenese shepherd laid the burned bones of his daughter before her throne, Daenerys had her dragons chained, but Drogon killed four men and escaped, flying north toward the Dothraki sea. He returned in 300 AC to Daznak's Pit, drawn by blood and noise, and there Daenerys took up a whip, climbed upon his back, and flew for the first time; he carried her to his lair on a hill in the grass sea, his wings by then twenty feet from tip to tip, and would not be turned back toward the city.