Kay is ubiquitous in Arthurian literature but he rarely serves as anything but a foil for other characters. Although he manipulates the king to get his way, his loyalty to Arthur is usually unquestioned. In the Vulgate Cycle, the Post-Vulgate and Thomas Malory's "Le Morte d'Arthur", Kay's father Ector adopts the infant Arthur after Merlin takes him away from his birth parents, Uther and Igraine. Ector raises the future king and Kay as brothers, but Arthur's parentage is revealed when he draws the Sword in the Stone at a tournament in London. Arthur, serving as squire to the newly knighted Kay, is locked out of the house and cannot get to his brother's sword, so he uses the Sword in the Stone to replace it. Kay shows his characteristic opportunism when he tries to claim it was in fact he that pulled the sword from the stone, not Arthur, making Kay the true King of the Britons, but he ultimately relents and admits it was Arthur. He becomes one of the first Knights of the Round Table, described as "best worthy to be a knight of the Round Table of any", and serves his foster-brother throughout his life.