The daughter of Sir Agravadain des Vaus de Galoire, she was the victim of what seems to have been either a practical joke or a venture by Merlin into planned genetics.
Five days after the visit of Ban and Merlin, a rich knight of the neighborhood asked for the Damsel’s hand in marriage. She meekly but firmly refused, confessing at last that she was with child by King Ban. Sir Agravadain requested the young lover, whose name seems to have been Leriador, to wait for two years and then try again. Instead, Leriador besieged the castle and Agravadain had to beat him off.
The Damsel seems to have remained unmarried after giving birth to her son, Sir Ector de Maris, who resembled his father, King Ban.
After Sir Agravadain’s death, the castle was held by his son, Ector’s uncle and the Damsel’s brother. The Damsel seems never to have forgot her lover, for she always kept a sapphire ring he had given her. This ring had been given him by his wife, Elaine of Benwick, who kept another one like it. Years afterwards, the Damsel des Mares was able to prove to Lancelot that her son was his half-brother by means of this ring.
The damsel left her family’s castle at least once, to travel to the Royal Minster in Gaul and meet Lancelot’s mother, Queen Elaine.