Read the excerpt from Poe’s "The Fall of the House of Usher." [S]he succumbed (as her brother told me at night with inexpressible agitation) to the prostrating power of the destroyer; and I learned that the glimpse I had obtained of her person would thus probably be the last I should obtain -- that the lady, at least while living, would be seen by me no more. How does this excerpt provide information about the narrator of the story?