When the main character meets Usher what does he think of his mental state in "The Fall of the House of Usher" by Poe?

When the narrator finally reaches Roderick Usher, the latter lies on his couch for a period of time before getting up to greet him.

Although Usher at first shows a degree of vivacity born from his natural tendency to be polite, the narrator notices that there is a deep, underlying sense of doom and sadness that consumes his old friend.

I gazed upon him with a feeling half of pity, half of awe. Surely, man had never before so terribly altered, in so brief a period, as had Roderick Usher!

Usher's complexion is described as "cadaverous," and his eyes are seen as "liquid" as well as unnaturally bright. His entire presence conveyed a sense of grief and loss, and yet some features in the man, such as his hair, his "arabesque expression" and that brightness of the eye made him look all the more conflicting, and made the narrator wonder if Usher was an actual, typical human being.

It was that, along with the nervous and anxious message sent to the narrator by Roderick, that led him to realize that something was very wrong with this man who already was strange by nature to begin with. The narrator was quite sure that something out of the normal was going on.