Son Yvain the Bastard and one of Arthurís squires in Perlesvaus.

Arthur announced that he was going to take Cahus on a pilgrimage to the chapel of St. Augustine in the White Forest. On the night before the scheduled journey, Cahus had a dream that he visited a shrine near the chapel, took a golden candle, and was stabbed in the side by a Black Knight.

He awoke in Arthurís castle and found to his astonishment that he was holding a golden candle, and had a dagger stuck in his side. He perished of the wound after presenting the candle to his king. A similar story is related about an unnamed attendant of Arthurís in John of Glastonburyís chronicle.