Oh, Byron. "Mad, bad, and dangerous to know," as Caroline Lamb (yes, Hannah's Caroline Lamb) famously called him. Byron was the Edward Cullen of his day: the brooding bad boy whom everyone found irresistible. What, however, is he doing in Arcadia?
The first answer is that he's not really in Arcadia at all: while it may seem like the characters are talking about him constantly, he never makes a personal appearance. No doubt this is to keep the people in the front row of the theater from swooning at his smoking hotness. It also gives the audience something in common with Byron researchers, as they try to imagine someone they can never know directly.
The play humanizes Byron: when the nineteenth-century characters talk about him, it's not as a distant celebrity but as a fellow (and often not particularly admirable) human being. What's the effect of this double portrayal of Byron as houseguest and famous poet? How does seeing Byron from these two different perspectives differ from seeing him from either alone, and what does that suggest about the weaknesses of the historical (or, for that matter, the contemporary) viewpoint?