Final answer:
The story where a friend visits Roderick Usher is "The Fall of the House of Usher" by Edgar Allan Poe. It conveys themes of decay and doom, underscored by the use of mirror reflections to symbolize the decline of both Roderick and the Usher family.
Step-by-step explanation:
The Edgar Allan Poe tale where a friend visits Roderick Usher in his home is "The Fall of the House of Usher". This is a classic story of Gothic horror, where the narrator, upon receiving a letter from Roderick Usher, who had been his childhood friend, arrives at the Usher family estate to find a scene of utter desolation and decay.
Through vibrant and eerie descriptions, Poe paints a picture of Usher's mansion as a place of insufferable gloom, with the house itself symbolizing the decay of the Usher family. Roderick, who is suffering from acute mental and physical illnesses, embodies the wasting away of life, being mirrored by his twin sister and the dilapidated state of the house.
The narrative serves as a bleak allegory for humanity's inescapable doom, a key theme in Poe's work, heavily utilizing mirror reflections to enhance the feelings of darkness and fatalism.