Two entries with the name Ydain.
A lady at Arthur’s court who married Sir Cador of Cornwall.
First Continuation of Chrétien’s Perceval | Attributed to Wauchier of Denain, c. 1200
A maiden that Gawain rescued from Sir Licoridon who tried to rape her. She flirted unabashedly with Gawain, and Gawain fell in love with her. Later, however, she decided to abandon Gawain for a knight with what she perceived to be greater sexual prowess. Gawain defeated this rival knight and then turned Ydain over to the dwarf Druidan, a loathsome little hunchback in punishment.
Appearing in La Vengeance Raguidel, she is identical to an unnamed character in Le Chevalier a L’Épée.
La Vengeance Raguidel | Raoul, possibly Raoul de Houdenc, early 13th century
De Wrake van Ragisel | Early to mid-13th century