Character Analysis
The narrator of "The Piazza" is sort of Melville; the house he talks about is Arrowhead, a home he purchased in 1850 in Massachusetts. The piazza is Arrowhead's porch, where Melville sits and dreams the dreams that become his stories.
You don't really learn a lot about the narrator, aside from the fact that he is certainly a dreamer. He seems to have been to sea, as Melville had—while looking out to the hills he says, "one is often reminded of the sea." (1.18) He likes making allusions to literature; the first lines of the story are a throwaway reference to Shakespeare's Cymbeline.
What's most interesting about the narrator, maybe, is the ways he doesn't quite seem to be Melville. Melville had a wife, and kids. They're never mentioned in "The Piazza." Instead, the narrator's main relationship is with a fantasy woman, whose loneliness seems to reflect his. So as a character he becomes defined by disconnection; he seems lost in his own head and dreams, beyond human contact. But that characterization of (the real) Melville is itself a dream. The narrator, who seems real, is in fact a fiction, just like Marianna, who "he" dreams up.
Narrator's Timeline