Tyraxes hatched from the egg laid by royal decree in the cradle of Prince Joffrey Velaryon, youngest of Rhaenyra's three sons by Laenor, and was a young and strong dragon by 129 AC, growing every year though a little smaller than his brothers' Vermax and Arrax. The books do not give his color; the author has described him to an illustrator as pale violet, with dark purple horns and purple flame. When the Dance of the Dragons began he could carry his rider long distances but was not yet big enough for battle, and Rhaenyra refused Joffrey's every plea to fight.
He carried Joffrey and Rhaena of Pentos to the Vale to be wards of Lady Jeyne Arryn, and came back to King's Landing after the city fell to the blacks in 130 AC, when Joffrey, not yet thirteen, was named heir and swore to keep Tyraxes for the defense of the Red Keep. The dragon lairs in the Dragonpit, and when the Shepherd's mob marched on the pit Joffrey, forbidden to go to him, took his mother's Syrax instead and was thrown to his death. Tyraxes drew back into his lair as the dragonslayers came, and burned so many in the passage that the way was choked with the dead, but the mob climbed over their own corpses, and the young dragon, tangled in his chains, was hacked to death.