An unnamed daughter of King Bagdemagus helped deliver Lancelot from Castle Chariot, where he was being held by Morgan and other queens. The damsel’s condition for helping Lancelot escape was that he help her father in a tournament against the King of Norgales (North Wales).
Vulgate IV mentions a stepsister of Meliagrant. She hated him because he had calumniated her, causing her father to cut her off, so that she retained only a poor inheritance from her mother.
This damsel was benefactress to the wife of a serf named Roliax, whom Meliagrant made Lancelot’s jailor. Thus the stepsister was able to help Lancelot escape. This damsel may be identical with Malory’s daughter of King Bagdemagus, or she may be a separate character; she may even be a daughter of Bagdemagus’ wife, perhaps a former marriage, and not of Bagdemagus himself. In her story we can definitely recognize that of Bademagu’s daughter in Chrétien’s Lancelot, mixed in with certain elements Chrétien used with other ladies in Yvain.
Lancelot later learned, as he rode through the wood of Sapine, that Meliagrant’s stepsister was to be burned at Florega the next day for the death of Meliagrant. Lancelot saved her in the nick of time and threw her accuser into the fire instead.