Referring to Poe's "The Fall of the House of Usher," what does this question mean: "What is the situation that revolves around the characters?"?
The question "What is the situation that revolves around the characters?" is a fairly standard literary question that aims at directing a student to a specific aspect of literary criticism, namely, how the situations of the plot affect and involve the characters. Firstly, examine the definition of situation as stated by Random House Dictionary (on Dictionary.com), which may be a condition, a case, or a plight as well as a state of affairs or a combination of circumstances. Therefore one paraphrase of what the question is asking can be, "What is the state of affairs or plight that revolves around the characters?"
Secondly, the phrase revolves around is actually a metaphorical figure of speech, seeing that plights and states of affairs don't actually move in circles around characters. This metaphorical figure of speech is in fact an idiom, which is defined as an expression that has a nonliteral meaning that can be understood based upon cultural agreement of meaning (e.g., "You're a Babe Ruth!"); in other words, what revolves around means in America is not likely to be what it means in Korea or elsewhere. [Which, incidentally, is why idioms give learners of a second language so much difficulty: such learners don't have the cultural background necessary for understanding idioms, tied as they are to cultural meaning.]
According to McGraw-Hill Dictionary of American Idioms and Phrasal Verbs, the culturally agreed upon meaning of the idiom revolves around is something that is primarily concerned with or centered upon someone (or something). In other words, a situation that revolves around characters is a state of affairs or a plight that is centered upon or primarily concerned with the characters. Therefore a paraphrase of the question might be, "What is the state of affairs or plight that primarily concerns or centers upon the characters?"
Thirdly, since no particular characters are singled out, it must be assumed that the question refers to all major characters, who would be the unnamed narrator, Roderick Usher and Madeline Usher. So what situation (state of affairs or plight) revolves around (centers upon or concerns) all three characters? Well, Roderick sought the narrator's company as his guest at the House of Usher because he was suffering some terrible nervous, psychological disturbance. Roderick was suffering this disorder out of concern for Madeline's deteriorating health. He is concerned for Madeline because he feels an impending and horrible doom coming upon the family and manor of Usher. Putting it all together, it is now possible to say that the situation revolving around the characters is the impending doom to the House of Usher, both to the family of Usher and the manor house of Usher.
The situation that revolves around the characters is one of evil and disease. Poe describes the Usher house as "a mansion of gloom," and Roderick is described as having "a ghastly pallor of skin."
Roderick himself says that his family is cursed. Although not stated, I believe that the evil curse stems from a possible cursed family secret. As a result, Madeline and Roderick are suffering from the physical and emotional affects of the secret. In addition, the house is also suffering from the affects of this secret and is increasingly falling apart. Interestingly, the title then has a two-fold meaning: the fall of the actual Usher house, and the fall of the Usher family.