Sir Brunor the Black was the son of Sir Brunor Senior the 'Good Knight without Fear,' and brother of Sirs Dinadan and Daniel. The unlucky knight lost much of his family before he arrived at Arthur's Court. His father was murdered and Sir Lancelot slew his brother, Daniel. The Knight of the Lake thus became his sworn enemy, but the two fought to a draw at Castle Dusbergo (possibly Dewsbury in Yorkshire) and seem to have instigated an uneasy truce thereafter.

Sir Brunor travelled to Camelot wearing his dead father's coat which he had vowed not to take off until his murder had been avenged. It did not fit Sir Brunor at all and, upon his arrival at the Royal Court, Sir Kay scoffed at him, dubbing him "La Cote Mal Tailliée" - the Knight of the Ill-Fitting Coat.

Such mockery, no doubt, did nothing for his reputation and Sir Brunor was rejected for a position in King Arthur's service. He departed in disgust but, later, Sir Gawain spoke out on his behalf and a messenger was sent to call him back to Court. Both he and a group of knights failed in this task and the latte were sorely defeated in combat. After a number of adventures however, Sir Brunor did return and King Arthur knighted him.

Sir Kay continued his attempts at humiliating the Black Knight by arranging his first joust to be against the King Arthur's jester, Dagonet. However, Sir Brunor soon proved his worth to his peers by rescuing Queen Guinevere from a lion that had escaped from the King's menagerie. Arthur thus decided, at the request of Ill-Speaking Maiden, to send him to avenge the death of a knight in Sorelais (possibly the Isle of Man). The Black Knight lacked skill in jousting - being badly defeated by Sirs Bleoberis and Palamides on his journey - but, on foot, he was unmatchable and slew a dozen knights at the Castle Orguellous. He was captured and imprisoned at Pendragon Castle by Sir Brian of the Isles, but was rescued by Sir Lancelot. This appears to have caused their reconciliation and the two became good friends. They went to Sorelois together and killed the six evil brothers named in Brunor's quest.

On home journey, Sir Brian was finally evicted from Pendragon Castle and Lancelot gave it to Sir Brunor. Arthur made him a Knight of the Round Table, he married the Ill-Speaking Maiden, and they lived together in their Northerly fortress.