Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Performance
The play doesn't have a narrative technique—it's a play, after all. This helps Webster heighten certain effects that might have been different in a novel: he's able to remain non-commital towards some of his characters. If the audience finds Flamineo and Vittoria more attractive and interesting than Monticelso and Francisco, there's nothing Webster can really say about it. The flash and dash of his evil characters are challenging—but they might not be so challenging if Webster was writing a novel and saying, "And then the wicked Vittoria did thus…" or whatever.