Sir Tristan de Bois, also known as "The Black Knight", was the older brother of Ygraine and Agravaine de Bois, the brother-in-law of Uther Pendragon, and one of Arthur's maternal uncles. A former friend of Uther, he turned against him after the death of Ygraine, blaming Uther for her demise, and challenged Uther to single combat, with Uther defeating him. Many years after his death, Tristan became the deceased uncle-in-law of Guinevere, the wife of his nephew, Arthur. About twenty years...