One of the central themes underlying the short story, The Fall of the House of Usher, is that of the nature of the house. The way it is described and the way it is so mysterious. Another central theme about this story is the nature of the people that live in the house. They are portrayed very much in the same manner throughout the story. Thus, they have several similarities with each other. All of which are of a bad feeling, showing how bad things are for the people and the house. These similarities are very well laid out in the story and are, I believe, meant to be something to be considered when reading it.
At the beginning of the story there is a very negative feeling being attached to the appearance of the house. He uses a couple of things to try and make you feel negatively about this place. He used words and phrases such as: insufferable gloom, vacant, black and lurid, and the rank sedges were mentioned too. These are obviously there to give a sort of a bad connotation, or bad karma, to the house. He speaks of how the house has a wild inconsistency and how each individual stone is starting to decay and fall apart. Suggesting that the house has many problems, all problems that could possibly lead to the destruction of a house.
Some accounts even take it as having a kind of gothic feeling to it. Which, after reading the descriptions about it, is very understandable. Another word thrown around when speaking about the house is ghostly. Other phrases such as, through many dark and intricate passages and ebon blackness also help to set the mood correctly. They all set up the fact that some sort of fearful event is going to take place soon.
All these things put together and a few others help to connect the house to Roderick and Lady Madeline. When the narrator first sees Roderick after a long period of time, he thinks that he resembles that of a corpse. Then Roderick tells him the reason for his appearance, why he looks so bad. He said he had an illness that was a morbid acuteness of the senses. The word morbid, when used anywhere, has very strong meaning and it is of the negative type. He uses the word tortured when he is describing his eyesight and says that even the slightest sound is almost unbearable. Thinking about having all of these symptoms put together is a very bad picture to paint in your mind. His condition, in this case, is very comparable to that of the condition of the house.
Then Madeline is introduced, and the first thing stated about her is that she has an unknown illness. Her illness is so bad that she cannot respond to any outside stimuli. She is never even seen again by the narrator after this brief introduction. The way both of the characters were introduced, with their appearance and the descriptions of all of the illnesses that they have, gave them a very negative connotation. Poe is trying to set the mood of the story by throwing out all of these negative things about the structure of the house and how it is decaying and falling apart. He is doing the same by telling about Roderick and Madeline and how they are sick and virtually doing the same as the house is, rotting away and slowly coming apart.