A fairy companion of Morgan le Fay.
When Arthur’s knights Claris and Laris were Morgan’s prisoners, Madoine fell in love with Laris. Laris and Madoine had a child together, but Laris eventually fell in love with Princess Marine.
Madoine stalked Laris through some of his adventures and eventually abducted him, but he was rescued by Claris.
Source
Claris et Laris | 1268