A strange aspect of modern Renaissance Faires is the blending of facts and fantasy. You literally can go to the event and see a fairly historically correct representation of Queen Elizabeth and her Court, right down to the period correct buttons, then look over and see two gals dressed as a green fairy, orc, or wizard...
In the beginning there was order, culture, purpose...this was Rome, and Britain was under the grace of Caesar. Then everything went dark. From the ashes of Empire rose legends of fairies, elves, trolls, orcs, Arthur and a magician named Merlin. These stories of fantasy crop up as the last vestiges of roman rule diminished into the void of history and the dark ages covered the land like an angry cloud. Roman withdrawn occurred in 410 A.D., the 5th century, and Britain became a free-for-all, mish-mash of petty principalities, warring tribes and dirty Celts. From these broken remains of Villas, frescos, and mosaics, sprang a mythical king, a last vestige of the old order and rule left behind as the Empire fought off uncivilized hordes breaching the gates of what was once the pinnacle of civilization. Visigoths aside, Britain had become a very mysterious place. A mythical outpost, open to the crafting of fantasy.
For roughly 500 years, the Dark Ages consumed Britain. Full of the remnants of Roman rule and the dawn of foreign invasions from Germanic tribes such as the Saxons, there was much room in which to fantasize, and we can thank Geoffrey of Monmouth for much of it. Historia Regum Britanniae or The History of the Kings of Britain is perhaps his best known written work. Despite the grand title, it is a complete work of fiction, plagiarism and balderdash. One could claim that Tolkien's Lord of the Rings series is history, but we all know it's a made up fantasy, a very good story but a story nonetheless. What it has given us is the Arthurian Legend, and Merlin. Geoffrey was writing this around 1136, less than a hundred years after the Norman Conquest in 1066, so the time was ripe to wax nostalgic on Britain's royal past. Wax he did. The work purports to take the royal line all the way back to the royal family of Troy, but all it really does is cement legend, and create a line of stories to explain a succession of crowned heads who may or may not held sway over divine leadership of the island. Merlin of course, makes his appearance, and plays the part of magically disguising Arthur's father, High King of Britain Uther Pendragon so he can impregnate Gorlois, the wife of the Duke of Cornwall with whom he has felt the itch of rapine love. After this, Merlin fades from the story...
Much has been added over the years, and the Merlin in the Arthurian story has grown from some druidic shaman to a wise wizard counseling Arthur in his youth and directing him on the path of kingship. Even the Lady of the Lake gets into the act as Merlin's wife, who ends up killing him in later versions of the tale...
In all fairness, the character of Merlin is probably based on a real individual who lived shortly after the Fall of Roman Britain, somewhere in the 6th-century. Geoffrey likely based him on the older Welsh legend of a wild mad poet named Myrddin Wyllt, detailed in the 9th-century Historia Brittonum by Nennius. If Merlin was a real man, the earlier work is probably as close to reality as we are going to get. Geoffrey made him a mythical character, spawn of an Incubus or the Devil, able to fly gigantic stones from one place to another, specifically to relocate Stonehenge, leap tall building in a single bound...Nennius on the other had paints a more reasonable picture of the man, albeit still endowed with magical abilities. In Historia Brittonum Merlin's father is a Roman consul...and his name is more in line with Pax Romana, Ambrosius.
Whether Merlin hailed from Wales, the Scottish borderlands, a desolate hill in England, or out of the dark forest, Geoffrey's transformation sealed the character as one of lore. He changed the perception of Merlin, even changing the name to Merlinus, as Latinizing Myrddin to Merdinus resembles merde, a word in French (a language recently introduced by Britain's Norman conquerors) referring to something very specific...
I have to wonder why Dark Age legends, and the costumes that accompany them are rife at an event portraying the 16th and early 17th centuries. Don't get me wrong, it's fun, but it's kind of weird, and very peculiar to American Renaissance Faires. It's not just Merlin, you have fay people, goblins, monsters, hot chicks with tusks, witches, warlocks and old men wearing hats straight out of Disney's Fantasia. Add to that a smattering of Dr. Who look-alikes, Star Wars stormtroopers and Star Trek red shirts...yeah, History pretty much circles the bowl.
I will say this in a defense of magic and mythical things at faire...the Renaissance was a turning point in our collective understanding of the World around us. As science became humanity's new focus, there was no more room for magic to explain what we could not understand. There was no more room for faeries, and orcs...Merlin and magic, goblins and witches. Something died within us, and what we perceived was replaced with something just as unexplainable to the common man and woman. Science killed something in us, something that we could accept and relate to. Maybe seeing a little magic at a Renaissance faire reminds us that there used to be something other than a test tube or a microscope...perhaps Merlin, and his pointy hat filled with moons and stars, reminds us of a World without cold, clinical, scientific realities...