Give a detailed description of Roderick Usher.

The narrator says that, "Surely a man had never before so terribly altered. . . " He is pale and has large eyes, he looks like a living corpse. Roderick's physical and mental decline mirorrs the decay of the house. 

Roderick is a twin to his sister Madeline.  She is not well, thus he is not well.  There is some history of perhaps incestuous behavior, but the house fall into rubble at the end when Roderick dies at the end.  He looks almost deathlike and somewhat mysterious as he meets the narrator who has come to visit.