When their father dies in battle against King Claudas, Lionel and Bors are rescued by the Lady of the Lake and raised in her underwater kingdom alongside her foster-son Lancelot. Like all his family, Lionel becomes a Knight of the Round Table. While travelling with Lancelot as a young man, Lionel is captured by the rogue knight Turquine, who whips him with briars and throws him in the dungeon. The scenario repeats itself later while he is on the Quest for the Holy Grail, where he proves very unworthy of the blessed object by trying to kill his brother for not rescuing him. Bors had seen Lionel getting beaten and led away, but had to make a decision to save either him or a young girl being dragged in the opposite direction. He saves the girl, and fears Lionel dead. But Lionel escapes, and attacks Bors the next time they meet. Bors proves himself worthy of the Grail when he refuses to fight back, and Lionel kills a religious hermit and Sir Calogrenant, a fellow Knight of the Round Table, when they try to protect Bors from his wrath. Before Lionel can strike his brother, however, God intervenes and immobilises him. Lionel and the rest of his family follow Lancelot into exile when the affair with Queen Guinevere is exposed. Lionel participates in the battles against King Arthur and becomes King of Gaunnes. After the Battle of Camlann, Lancelot's family returns to Britain to defeat the remainder of Mordred's forces. Lionel is slain by Mordred's son Melehan; Bors avenges his death. Sir Lionel is the subject of the late-medieval folk ballad "Sir Lionel", recorded as Child Ballad 18 and Roud No. 29, in which he slays a giant wild boar. This song has much in common with a medieval tale about a knight who slays a terrifyingly fiendish boar in Sidon, in the fourteenth centuryromance of Sir Eglamour of Artois. The terrible swine is a frequent foe in romantic tales, for instance the beastTwrch Trwyth in Culhwch and Olwen. The song was recorded in Appalachia as late as the early 20th century. Popular variants include "Old Bangum" and "Wild Hog".
Modern works
In the musical Camelot, Lionel is the knight brought back to life by Lancelot after he accidentally kills him in a joust.
Lionel appears in the 1998 animated filmQuest for Camelot as the father of the protagonist, Kayley, who wished to follow her father's footsteps. During the beginning of the film, Lionel is killed by the main antagonist, Lord Ruber, who intends to claim the throne of Camelot for himself, while trying to kill King Arthur, whom Lionel defended before he died.