Editing Sir Kay (section)

===''Culhwch ac Olwen''===
{{main|Culhwch and Olwen}}
[[File:Ysbaddaden.jpeg|thumb|Culhwch and his companions at Ysbadadden's court in [[Ernest Wallcousins]]’ illustration for ''Celtic Myth & Legend'' (1920)]]

[[Culhwch]]'s father, [[Cilydd|King Cilydd son of Celyddon]], loses his wife [[Goleuddydd]] after a difficult childbirth. When he remarries, the young Culhwch rejects his stepmother's attempt to pair him with his new stepsister. Offended, the new queen puts a curse on him so that he can marry no one besides the beautiful [[Olwen]], daughter of the giant [[Ysbaddaden]]. Though he has never seen her, Culhwch becomes infatuated with her, but his father warns him that he will never find her without the aid of his famous cousin Arthur. The young man immediately sets off to seek his kinsman. He finds him at his court in [[Celliwig]] in Cornwall and asks for support and assistance. Cai is the first knight to volunteer to assist Culhwch in his quest,<ref>S. Davies translation, ''The Mabinogion'' (Oxford 2007) p. 189.</ref> promising to stand by his side until Olwen is found. A further five knights join them in their mission. They travel onwards until they come across the "fairest of the castles of the world", and meet Ysbaddaden's shepherd brother, Custennin. They learn that the castle belongs to Ysbaddaden, that he stripped Custennin of his lands and murdered the shepherd's twenty-three children out of cruelty. Custennin set up a meeting between Culhwch and Olwen, and the maiden agrees to lead Culhwch and his companions to Ysbadadden's castle. Cai pledges to protect the twenty-fourth son, [[Goreu fab Custennin|Goreu]] with his life.<ref>S. Davies translation, ''The Mabinogion'' (Oxford 2007) p. 193.</ref> The knights attack the castle by stealth, killing the nine porters and the nine watchdogs, and enter the giant's hall. Upon their arrival, Ysbaddaden attempts to kill Culhwch with a poison dart, but is outwitted and wounded, first by [[Bedivere|Bedwyr]], then by the enchanter [[Menw]], and finally by Culhwch himself. Eventually, Ysbaddaden relents, and agrees to give Culhwch his daughter on the condition that he completes a number of impossible tasks (''anoethau''), including hunting the [[Twrch Trwyth]] and recovering the exalted prisoner [[Mabon ap Modron]].

Cai is a prominent character throughout the tale and is responsible for completing a number of the tasks; he kills Wrnach the Giant, rescues [[Mabon ap Modron]] from his watery prison and retrieves the hairs of Dillus the Bearded.<ref>S. Davies translation, ''The Mabinogion'' (Oxford 2007) pp. 202-7.</ref>  However, when Arthur makes a satirical [[englyn]] about Cai, he grows angry and hostile towards the king, ultimately abandoning the quest and his companions. The narrative tells us that Cai would "have nothing to do with Arthur from then on, not when the latter was waning in strength or when his men were being killed." As a result, he did not take part in the hunt for Twrch Trwyth.