Final answer:
Roderick Usher is described through the narrator's impressions as being mysterious, aloof, and with an air of melancholy. Usher's altered appearance and cadaverous demeanor evoke a sense of unease in the narrator, contributing to the story's fatalistic theme.
Step-by-step explanation:
The character of Roderick Usher, as narrated in Edgar Allan Poe's The Fall of the House of Usher, is richly described through the impressions of the narrator. Usher is presented as an enigmatic figure showing excessive reserve, a man who has notably altered in appearance reflecting a deep-rooted melancholy. His face is described as cadaverous with a ghastly pallor, and his large, luminous eyes exude a sense of eeriness. The narrator feels a mix of pity and awe towards Usher, acknowledging his sincerity despite the initial presumption of an overdone cordiality. Usher's behavior includes moments of 'mad hilarity' in his eyes and a constrained hysteria, contributing to an unsettling presence. Combined, these descriptions portray a person who contrasts greatly with the potential options of being confident and charismatic (A) or jovial and extroverted (C). He is also not characterized as arrogant and domineering (D), which leaves us with option (B) that the narrator describes Usher as mysterious and aloof, with an air of melancholy, which aligns with the overarching fatalistic theme present throughout the tale.