Morgan le Fay started as Arthur's healer before becoming his enemy
The first written Morgan was no villain. Around 1150, Geoffrey of Monmouth made her the chief of nine magical sisters on the Isle of Apples, where the dying Arthur was carried after Camlann. Only as the legend grew did she turn into the scheming half-sister of the later prose romances, and her name probably means sea-born.
Morgan goes by dozens of spellings, from Morgana and Morgaine to Morgue, and her nature shifts just as much. Depending on the author she is fairy or mortal, helper or menace, Arthur's sister, half-sister or no relation at all. What stays constant across medieval and later versions is an unpredictable double edge, a capacity for both kindness and harm.
Her earliest appearance, in Geoffrey's Vita Merlini, spells the name Morgen, probably from Old Welsh or Old Breton for sea-born. An Old Irish relative, Muirgen, was a shapeshifting saint tied to the sea. The name has nothing to do with the modern Welsh man's name Morgan, and the tag le Fay is a pseudo-French phrase popularised by Thomas Malory in the fifteenth century. Geoffrey's nine sisters strongly resemble the Gallisenae, nine priestesses said to live on the isle of Sena, today Île de Sein, off Gaul.
Scholars trace other threads too. Welsh tradition offers Modron, a supernatural mother descended from the goddess Dea Matrona, whose children by Urien appear in Welsh Triad 70; later romances likewise make Urien Morgan's husband and give them a son, Yvain. Irish legend and saints' lives may have contributed, and even Empress Matilda has been suggested as an influence. One candidate for a historical Arthur, Artuir mac Áedán, had a sister called Maithgen.
As the Arthurian story expanded, so did Morgan's role and her moral murkiness. The thirteenth-century prose cycles, such as the Lancelot-Grail and the Post-Vulgate, and the later Le Morte d'Arthur make her the youngest daughter of Igraine by her first husband, so Arthur, Igraine's son by Uther Pendragon, becomes her half-brother. She is unhappily married to Urien and trains under Merlin. Other tales keep her as the undying queen of Avalon. After a long spell out of fashion she returned strongly in the twentieth and twenty-first centuries, often merged with her sister, the Queen of Orkney.
Source: Morgan le Fay