For a man who is Sir Ector's son, King Arthur's foster brother and later seneschal, as well as one of the first Knights of the Round Table, Kay seemingly would be better suited as the court jester according to modern works. Although twentieth century works may point a laughing finger at Kay, older pieces of literature give Kay a prequel facelift if you will. Although Kay may have literary alter egos, he exhibits consistent core values: bravery, willingness to serve, trust, and loyalty.
Kay is of the earliest characters to be associated with the Arthurian cycle, appearing in a number of early Welsh texts, including Culhwch ac Olwen, Geraint fab Erbin, Iarlles y Ffynnon, Peredur fab Efrawg, Breuddwyd Rhonabwy, Pa Gur yv y Porthaur and the Welsh Triads. As seen in numerous works, both timeless and modern, Kay has often been held very dear by Arthur and in great regard by the other knights for his bravery and willingness to serve. In Welsh tradition, Before Kay’s birth, Cynyr Ceinfarfog prophesied that his son's heart would be eternally cold, that he would be exceptionally stubborn and that no one would be able to brave fire or water like him. Kay is attributed with a number of further superhuman abilities, including the ability to go nine days and nine nights without the need to breathe or to sleep, the ability to grow as "tall as the tallest tree in the forest if he pleased" and the ability to radiate supernatural heat from his hands. Furthermore, it is impossible to cure a wound from Kay’s sword. As proven by King Arthur in Pa Gur, Kay’s mid-thirteenth century incarnation possessed mighty battle prowess:
“When he would drink from a horn,
He would drink as much as four;
When into battle he came
He slew as would a hundred.”
Pa gur is notable for being one of the earliest vernacular Arthurian works, and for alluding to several early adventures of Arthur which are now lost. Kay is also a prominent character throughout another Welsh tale: Culhwch ac Olwen. He is responsible for completing a number of the tasks; he kills Wrnach the Giant, rescues Mabon ap Modron from his watery prison and retrieving the hairs of Dillus the Bearded. Kay is the first knight to volunteer to assist Culhwch in his quest, promising to stand by his side until Olwen is found. This willingness to serve an unfamiliar man proves that this willingness is one of his core values as a worthy knight. The knights attack by stealth, killing the nine porters and the nine watchdogs, and enter the giant's hall. Kay pledges to protect the twenty-fourth son, Goreu with his life after the giant has killed his 23 brothers. Kay and Bedivere appear in Geoffrey of Monmouth's Historia Regum Britanniae, and aid Arthur in defeating the Giant of Mont Saint-Michel. Geoffrey makes Kay the count of Anjou and Arthur's steward, an office he holds in most later literature. Kay is a main character in the first three books of T. H. White's The Once and Future King, The Sword in the Stone and The Queen of Air and Darkness. His portrayal is based on Malory's account of Arthur's upbringing, but White adds a number of new elements to the story, including one in which the young Kay kills a dangerous griffin with the aid of Robin Hood and Maid Marian. White's Kay is quick-witted and often mean, but always a loving foster brother to Arthur, whom he calls "the Wart".
An instance to glimpse Kay’s worthiness as a loyal knight is in the 1970s HTV series Arthur of the Britons. In this version of the legend, Arthur is a Celtic chieftain and Kay is a Saxon orphan, raised together as brothers by an adoptive father, amongst the Celts. He is portrayed as somewhat hot-headed and sometimes distracted by female company, but a fiercely capable warrior, sometimes favouring an axe-weapon, and Arthur's most trusted and loyal friend. Romance rarely deals with Kay's love life, an exception being Girart d'Amiens' Escanor, which details his love for Andrivete of Northumbria, whom he must defend from her uncle's political machinations before they can marry. Kay’s loyalty is again highlighted in Gillian Bradshaw's Down the Long Wind series and Stephen Lawhead's Pendragon cycle. Bradshaw depicts Kay as a large man with fiery hair and a temper to match, but with a strong sense of honor and loyalty to Arthur while Lawhead writes that as a child Kay had a crippled leg and Arthur was one of the few who defended him. This earns Arthur his complete and unquestioning loyalty. In the 2011, American-Irish-Canadian adaption Starz TV series titled Camelot, Kay is portrayed as a loyal and protective older brother to Arthur. Although raised in a rural setting, he appears educated and somewhat idealistic, described by the actor who plays him as having "a world of book-smarts, but no practical experience [of how be a warrior]". Adhering to the core value of truth, Kay is the main character of Phyllis Ann Karr's 1982 novel The Idylls of the Queen. Expanding on a scene from the classic tales in which a knight is poisoned at Guinevere's feast and the queen is accused of the crime, Karr turns her story into a murder mystery with Kay as the detective attempting to discover the truth.
Although there seems to be much proof of Kay as a worthy knight, there are also several occasions in which he is left in the limelight for an entirely different reason: comedy and behavior. These natures range from merely cruel and malicious, as in the Roman de Yder or Hartmann von Aue's Iwein to humorously derisive and even endearing, as in Durmart le Gallois and Girart d'Amiens's Escanor. In Thomas Berger's 1978 Arthur Rex: A Legendary Novel, Kay is a somewhat foppish, sharp-tongued gourmand. Relieved to be freed from his bucolic upbringing in Wales, he takes charge of the kitchens at Camelot and yearns to make it a more sophisticated court. Arthur good-naturedly complains that Sir Kay is always serving him rich foods, when the king would rather just have simple meals. Kay supplies occasional comic relief in the book, but ultimately fights and dies with honor in the last battle against Mordred's host. He also appears in Philip Reeve's Here Lies Arthur as Arthur's loyal half-brother. This work follows the path of bathing Kay’s quests in an uncomplimentary light, designed to improve upon Arthur’s reputation. In the Welsh Romances Owain, or the Lady of the Fountain and Peredur son of Efrawg, Kay assumes the same boorish role he takes in the continental romances. However, manuscripts for these romances date to well after Chrétien de Troyes, meaning that Kay as he appears there may owe more to Chrétien's version of the character than to the indigenous Welsh representation. In works by de Troyes, He retains his hot-headedness and fiery temper from Welsh literature, but he is more or less an incompetent braggart. Chrétien uses him as a scoffer and a troublemaker; a foil for heroic knights like Lancelot, Ywain, or Gawain. He mocks the chivalric courtesy of Sir Calogrenant in Yvain, the Knight of the Lion, and he tricks Arthur into allowing him to try to save Guinevere from Maleagant in Lancelot, the Knight of the Cart, which ends in his humiliating defeat. In Perceval, the Story of the Grail, Sir Kay grows angry with Perceval's naïveté and slaps a maiden who says he will become a great knight; Perceval avenges her later when he breaks Kay's shoulder. Wolfram von Eschenbach, who tells the same story in his Parzival, asks his audience not to judge Kay too harshly, as his sharp words actually serve to maintain courtly order. Kay appears in the 1963 Walt Disney Studios film adaptation of The Sword in the Stone, in which he is outwardly boorish and bitter, and also constantly bullies Arthur. In the Vulgate Cycle, the Post-Vulgate and Thomas Malory's Le Morte d'Arthur, Kay shows his characteristic opportunism when he tries to claim it was he that pulled the sword from the stone, making him the true King of the Britons, but relents and admits it was Arthur. Although sometimes boorish, Kay never breaks his core value of loyalty to Arthur and his fellows. Scholars have pointed out that Kay's scornful, overly boastful character never makes him a clown, a coward or a traitor, except in the Grail romance Perlesvaus, where he murders Arthur's son Loholt and joins up with the king's enemies. This strange work is an anomaly, however.
Like all good knights, Kay comes to an end. Oddly, given his ubiquity, Kay's death is not frequently dealt with. In Welsh literature, it is mentioned he was killed by Gwyddawg and avenged by Arthur. In Geoffrey of Monmouth and the Alliterative Morte Arthure, he is killed in the war against the Roman emperor Lucius, while the Vulgate Cycle has him die in France, also in battle against the Romans. According to Malory's version of Book 5, Kay did not die in the war against Rome, but survived and later was part of a party sent to try and retrieve Excalibur's Sacred Scabbard, prior to the Battle of Camlann. He was also among the few people who survived the battle of Camlann, although it is ambiguous as to how he survived.