Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
This is a play without a narrator, and therefore has no particular narrative voice. It might be worth pointing out, though, that the audience seems to be intended to identify the most with Edmund. The tone of the play toward the other characters is quite a forgiving, which is consistent with Edmund's overall disposition. This comparison makes a lot of sense, when you think about the fact that Edmund is O'Neill's fictional recreation of himself.