<P> A number of Welsh sources also refer to Medraut, usually in relation to Camlann . One triad, based on Geoffrey's Historia, provides an account of his betrayal of Arthur; in another, he is described as the author of one of the "Three Unrestrained Ravagings of the Isle of Britain"--he came to Arthur's court at Kelliwic in Cornwall, devoured all of the food and drink, and even dragged Gwenhwyfar (Guinevere) from her throne and beat her . </P> <P> Tradition varies on his relationship to Arthur, but he is best known today as Arthur's illegitimate son by his half - sister Morgause, though in many modern adaptations she is merged with the character of Morgan le Fay . In earlier literature, he was considered the legitimate son of Morgause, also known as Anna, with her husband King Lot of Orkney . His brothers or half - brothers are Gawain, Agravain, Gaheris, and Gareth . </P> <P> Medraut is never considered Arthur's son in Welsh texts, only his nephew, though The Dream of Rhonabwy mentions that the king had been his foster father . However, Mordred's later characterization as the king's villainous son has a precedent in the figure of Amhar (or Amr), a son of Arthur's known from only two references . The more important of these, found in an appendix to the Historia Britonum, describes his marvellous grave beside the Herefordshire spring where he had been slain by his own father in some unchronicled tragedy . What connection exists between the stories of Amr and Mordred, if there is one, has never been satisfactorily explained . </P> <P> The 14th - century Scottish chronicler John of Fordun even claimed that Mordred was the rightful heir to the throne of Britain, as Arthur was an illegitimate child (in his account, Mordred was the legitimate son of Lot and Anna, who here is Uther's sister). This sentiment was elaborated upon by Walter Bower and by Hector Boece, who in his Historia Gentis Scotorum goes so far as to say Arthur and Gawain were traitors and villains who stole the throne from Mordred . </P>

What is the relationship between mordred and arthur