Brother of the Red Knight that Perceval killed as a youth.
In revenge for his brother’s death, Cahot joined the Lord of the Fens in waging a war against Perceval’s mother, Yglais, and her castle of Kamaalot (Camelot).
By coincidence, Perceval wandered into Cahot’s castle, the Key of Wales, looking for a night’s lodging. Cahot recognized him, and Perceval ended up slaying him in battle.
Source
Perlesvaus | Early 13th century