Who is Le Fresne from The Lais of Marie de France and what is their importance?

Le Fresne appears in Le Fresne. He is one of a set of twin girls who is abandoned by her mother outside an abbey. She is raised by the abbess and later attracts the love of the nobleman Gurun, who takes her to live with him but not to marry. She is loyal to Gurun, and her loyalty pays off when he becomes engaged to marry Le Fresne's sister. When her mother realizes who she is, she reveals Le Fresne's noble background, making her a suitable wife for Gurun. Le Fresne means "ash tree", and she is named so because she was discovered in an ash tree as a baby.