Younger of the twin sons of Lord Tymond Lannister, born minutes after his brother Ser Jason and so destined to walk in his shadow at the Rock and at court. He was knighted alongside Jason in their youth, rode at his brother's side to court Princess Rhaenyra Targaryen at Casterly Rock in 112 AC, and was made master of ships under the renewed Hightower ascendancy in the last decade of King Viserys I's reign. When the Dance of the Dragons broke out at the king's death he declared for Aegon II, was raised from master of ships to master of coin after the removal of Lord Lyman Beesbury, and at once took control of the royal treasury — quartering the Crown's gold and sending one part to the Iron Bank, one to Casterly Rock, one to Oldtown, and the last to bribes, sellswords, and bargains with the great lords.
After the fall of King's Landing to Daemon and Rhaenyra, Tyland was spared execution in the hope that torture would yield the secret of the divided treasury. He was blinded and gelded in the cells beneath the Red Keep, but kept faith with the gold and never named where it had gone; despite many months in the torturers' hands he kept his wits and his cunning too. When Aegon II retook the city Tyland continued on his master's small council until the end of the war, and was sent to the Free Cities to hire sellswords for a last campaign that the king's poisoning rendered moot. After Aegon III took the throne Tyland — whose execution that very king he had once proposed — was named the regent's Hand and served loyally and ably until the Winter Fever struck King's Landing in 133 AC. He ordered a strict quarantine of the city, was locked inside it with the rest of its inhabitants, and was among the last to die of the plague.