Who is Medrawt from Here Lies Arthur and what is their importance?

Medrawt is Arthur's nephew and the older brother of Bedwyr. Early in the novel he is a young warrior and chases Gwyna for a moment before she escapes. From that point forward, Gwyna dislikes Medrawt. Through most of the narrative Medrawt is devoted to Arthur. He also is something of a braggart though his skill at arms equals his opinion of himself. After Arthur murders Bedwyr, Medrawt, warned by Peredur, flees Aquae Sulis with his wife and household. At this point Medrawt gathers an army in opposition to Arthur and then meets him on the field of Camlan where a bloody battle ensues. In the battle Medrawt is killed, though so is Arthur. In modern Arthurian mythology, Medrawt, known as Mordred, is said to have personally killed Arthur. While Medrawt plays a significant role in the narrative plot he remains essentially a minor character in the novel.