1. There was more than one Merlin
The friendly grey-bearded helper from The Sword in the Stone is somewhat simpler and less ambiguous than the Merlin (or as he appears in the older Welsh versions ‘Myrddin’) of the early Arthurian Legends. This Merlin appears in three forms; Merlin Silvestris, a madman who wanders in the woods, Merlin Taleisin, a poet and practitioner of magic, and Merlin Ambrosius, the prophet.
2. There was also (possibly) more than one Guinevere
Some reports, including some of those linked with Arthur’s purported tomb at Glastonbury, refer to Guinevere as Arthur’s second wife. Although confusingly some of these versions claim the first wife was called Guinevere as well… It actually wasn’t uncommon for queens in early medieval Britain to change their names upon marriage in order to integrate better with the country they had married into. This probably made things easier for the husbands as well…
3. Lancelot turns up pretty late in the game
Lancelot was invented by the French and made famous by Chretien de Troyes in the twelfth century, who wrote the romances of Lancelot to amuse his powerful patroness the aptly named Countess of Champagne. While he and his affair with Guinevere quickly became part of the staple of Arthurian Legend, he was potentially so popular among the French because he provided a way for them all to have a good laugh at our English King Arthur. Something along the lines of, so your English King conquered France and Rome, but our French knight, he had sex with his wife, ha ha ha.