Who is Diabetes (a.k.a. Actor, a.k.a. Euripedes) from Without Feathers and what is their importance?

Although the actor Diabetes comes off as conservative early in the play, when he insists that the play have an ending and, later, that Doris not interfere, Diabetes also first proposes the idea of unscripted characters. When the play begins to unravel, Diabetes makes the unprecedented decision to take a bathroom break, something that would've been impossible in a tightly scripted context. This foreshadows the decision he will make later in the role of Euripides, when again the script fails.