The granddaughter of Queen Igraine (Ygerne), Clarissant is tall, beautiful, wise, gracious, and seems in every way a paragon. This may befit her status in more ways than one: her mother (presumably that woman whom later romances were to name Margawse) was pregnant with Clarissant when she followed Igraine to the Rock of Canguin. But as far as the outer world - even Igraine's famous son Arthur - knows, Igraine has been dead for sixty years when Gawaine finds her(!) and Gawaine has believed his mother (who is also Clarissant's mother) dead for twenty years.
By this and other indications, we may suspect at least the possibility that the Rock of Canguin belongs to the Otherworld, even a Christianized Otherworld. Could Clarissant conceivably have been born in Heaven without passing through earthly life and death? She might certainly strike one as healthily angelic. Small wonder if Guiromelant loves her - although from a distance, from the other side of an all but impassable river; Clarissant testifies that they have never actually met, but only passed messages, and her acceptance of him as her lover apparently remains tentative.
Clarissant was Gawaine's servant when he stayed at the castle Canguin Rock (Chrétien de Troyes) or Salie Castle (Henrich von dem Türlin). Chrétien left things in a pleasant tangle at Canguin: Gawaine knows the situation, for Guiromelant has told him; but Gawaine has not yet revealed his own identity to his grandmother, mother, and sister. He has revealed it to Guiromelant, who hates him, and they have arranged to fight as soon as Arthur's court can be summoned to see them. Meanwhile, Igraine and her people are hoping to make a match between Clarissant and Gawaine, whom they want to keep permanently as their lord; not yet knowing he is Clarissant's brother, they see only how well the pair suit each other. With Arthur’s help, she ended the hostilities between Gawaine and Guiromelant, and the two lovers were allowed to marry. I must confess that what Chrétien would have made of Gawaine's adventure at Canguin intrigues me far more than how he might have finished Percivale's Grail adventure.
From Ronan Coghlan's 'Encyclopaedia of Arthurian Legends', I learn that the French prose 'Perlesvaus' and, apparently, other continuators had Clarissant wed Guiromelant and give birth to a daughter, Guigenor. Wolfram von Eschenbach calls her Itonje.