I first read Sir Thomas Malory in the Baines edition when I was 16. The Scottish Lancelot of the Laik was written in a thick northern English around the time of William Shakespeare. It's not as beautiful as the Bard, but it is readable without specific training in Middle English or Old English (I do have that, but it's not necessary for reading this). The Scottish Lancelot is really just a Scottish redaction of the French Prose Lancelot, which was the bulk of the French Vulgate to which Malory frequently refers in Le Morte (when he says, "the Frenche booke sayeth," he means the French Vulgate cycle), for the most part, but there are always nuances that alter the flavor. Remember that Caxton's printing press was relatively new, and many books were still reproduced the old fashioned way: scribes re-wrote and even translated by hand. This was a manual translation really, but with every redaction, there are always changes to the story because the translator or scribe heard or read something different elsewhere and imposes his version of the story even when translating or manually reproducing a text. So, even the same story reproduced becomes a new permutation.