Perhaps not, for elsewhere in the Trioedd Ynys Prydein, a serious quarrel is recorded between the two, although full details are lacking as the story is not repeated in other sources. Arthur certainly hit Medraut and Guinevere also struck Medraut's wife, her sister, Guinevack (more properly Gwenhwyfach). Medraut then took his warband to Cornwall and invaded Arthur's palace at Celliwig. He dragged Queen Guinevere from her throne and beat her, before his party took to feasting and consumed all the food and drink in the place. Arthur later retaliated in a similar manner.

It is Geoffrey of Monmouth who first tells us that Medraut was a younger son of King Letan of Gododdin (Lothian) and there are late Scottish traditions of him, largely voiced by Hector Boece (1527). He portrays Medraut as a paragon of virtue. Since Arthur was conceived out of wedlock, Mordred - as heir of King Uther's only legitimate child, Anna - was the rightful King of Britain. Arthur agreed to leave him the Crown but later reneged on the deal. Furthermore, Queen Guinevere eagerly become Medraut's lover and deserted Arthur to join him in Gododdin. Hence the two fought at the Battle of Camlann. After Medraut's death, Arthur sent his wild hounds to Scotland to hunt down his adulterous Queen. They caught up with her at Meigle and ripped her to shreds.

Medraut supposedly had two sons and popular late tradition gives him a second wife, Princess Cwyllog, one of the many daughter of the great Northern King Caw. She supposedly became an anchoress at Llangwyllog on Ynys Mon (Anglesey) after the Prince's death, but it is doubtful whether she actually existed. Certainly the true tradition is that Medraut's wife was a daughter of the British King 'Gawolane' not Caw. King Cadwallon Lawhir of Gwynedd may be intended.

He should not be confused with Prince Medrod the son of King Cawrdaf of Fferreg.