In "Paul's Case", Willa Cather is quite specific in that this story is not meant to be biographical, or a tale in the typical sense. Instead, she uses the subtitle "A Study in Temperament" to explain its true nature. This is significant, because it implies that Paul's temperament and personality are different from other characters of his same age and time. Yet, without condemning or condoning his traits, Cather does offer several clues as to the different reasons why Paul is so special.
Although Paul has been well-raised by his father in an upper-class medium, he does not seem to connect with the world around him. He hates school and his teachers, he does not like his neighbors, and he is particularly sick of suburbia. His neighborhood seems to be attached to a moral and social code of hard work, church suppers, and neighborly dynamics which dramatically contrast with Paul's daydreams of fancy dress, palatial views, and delicate decor under the sounds of the opera. Paul's life seems to be a physical and ethereal conflict between his idealized life, and his true existence. This is exactly what constitutes Paul's case: he simply cannot stand, nor survive, "the norm". He is a slave to aesthetics: the world of beauty.
Therefore, Willa Cather may be presenting Paul as a true aesthete born outside of his time. An aesthete applies judgements of sentiment and gives emotional value to beauty in all of its manifestations. Rather than accepting life and reality as they are, an aesthete operates under the philosophical paradigm that beauty is the ultimate reality, and that anything that tampers with it should be considered unacceptable.
However, Paul does not label himself an aesthete in the story; "Aesthetics" are not even mentioned at all. Hence, it is arguable that Willa Cather is subtlety presenting to her audience the unique case of a child who is a natural-born aesthete rather than a mere follower of the philosophy: Paul may very well be a unique being whose rise and downfall are caused by his inherent and incessant quest for beauty.
Notice how Paul cannot stand the sight of ugly things, or the feeling of dinginess or dust. He much rather not smell daily smells such as those of cooking but, instead, prefers to smell the smoke and the fumes of paint that come out of the artificially-made palaces that make up the background of the operas played at his workplace, the Carnegie Hall.
Paul also appreciates flowers as they appear in the height of their beauty in bloom. This is also a sign of his aesthetic disposition. An example of this is when, once in New York, Paul admires the fake flowers behind the glass in one of the shops, as they appear to be fresh and beautiful while the snow outside the glass would have made them welted and dead. Similarly, he buries the beautiful red flower on his buttonhole at the first sign of its decay, shortly before he kills himself.
All these facts basically make up the character of Paul: one who is so aesthetically delicate that he is dangerously susceptible to the interference of real life. This is best explained in the following excerpt from the story
Perhaps it was because, in Paul's world, the natural nearly always wore the guise of ugliness, that a certain element of artificiality seemed to him necessary in beauty.
Concisely, the story shows in Paul's desperate need for beauty and his interminable quest for it, that he is a true and natural aesthete. This conflict constitutes his unusual personality.