The High Middle Ages - What's the Connection Between Arthur and Merlin?

All the characters that are described as seeking the holy grail were either made up or plucked out of folklore and stuck down at arthur's round table. Arthur was associated with a sorcerer called merlin, who very likely is inspired by a real person. Morgan lefay also only appears in arthurian legends in the 12 hundreds. Maybe some of these involved various, any number of minor war lord chieftains in sub roman britain. And if we want an arthur that is worthy of the name, you might say, maybe we have to say he's really a composite figure.