Guinevere became a major motif in the Lancelot-Grail of the 13th century ,
This story first appeared in Chrétien de Troyes 's Lancelot , the Knight of the Cart and became a major motif in the Lancelot-Grail of the 13th century , carrying through the Post-Vulgate Cycle and Thomas Malory 's Le Morte d'Arthur .
Guinevere