When the narrator meets Usher in "The Fall of the House of Usher," what startles him about his appearance and behavior?character change

First of all, the ominous setting of decay in the surroundings of the Usher mansion itself, unnerves the narrator as he approaches the home of the friend from his youth.  Then, as the narrator enters the mansion in "The Fall of the House of Usher," he notices "the discoloration of ages."  Into a dark and sorrowful room of "irredeemable gloom" the narrator sees his old friend rise and greet him with what the narrator first perceives as "an overdone cordiality," but later realizes is sincere.  However, what the narrator notices most is how changed Roderick Usher is.  In the "exaggeration" of his features, Roderick appears so different as to be unrecognizable.  His hair is now of a mere "weblike softness," and a strange luster is in his eyes of a face of "ghostly pallor."

It is interesting to note Poe descripption of the hair of Roderick:

 "all unheeded...in its wild gossamer texture, it floated rather than fell about the face, I could not, even with effort, connect its arabesque expression with any idea of simple humanity.

Arabesque is the word Poe uses for his technique of weaving and turning his narratives.  So, in a sense, this physical description of Roderick Usher foreshadows the turnings and twistings of Roderick's mind that are soon to follow, as well as the gothic effects to come.