Thomas Malory
Thomas Malory in "Le Morte d'Arthur" split him into two characters: Uwaine les Avoutres, the son of Urien and Uwaine les Adventurous, an unrelated knight. Yvain the Bastard and Yvain les Avoutres are also separate characters in the Scottish "Lancelot of the Laik". In "Perlesvaus", his own son named Cahus dies while while serving as Arthur's own squire on a strange adventure, killed by a giant in a deadly dream.