JD Salinger creates all angst in teens into one character
Holden Caulfield has a problem, and its a big one, you see, the kid, as young as he is, barely 17, has already had a nervous breakdown, and truth be told he hasn't recovered from it. But he has a good reason behind it, his kid Brother, a very likable and sweet child, a kid who wrote poetry on his baseball glove so he had something to read while standing out in the outfield waiting for something to happen, this kid, this sweet kid got sick and died, and Holden hasn't gotten over the idea. The idea that he lives in a world that is governed by rules that lets kids like that get sick and die, and all the bad people get along fine, the bad people don't even catch a cold.
The realization of the inevitability of death hits different people in different ways, for Holden, he basically fell to pieces. the death of his kid brother changed Holden, and he just can't see the point of following the prescribed course of all his friends and peers, scramble to get good grades in school, so you can go to a good college, and then get a good job and make lots of money, what's the point, you just might get sick and die along the way, and even if you don't, death will catch up with you anyway.
Everyone is tired of Holden being upset and being difficult, everyone else just wants to get along and nobody really cares if his kid Brother died, or if Holden is upset, nobody cares about anybody but themselves. Holden is rebelling in his own way, but how can you rebel against the laws of the universe. Holden feels very wised up, he see's life for the futile game that it is. Holden also has an obsession with protecting children from bad things, especially death. in many ways Holden is a boy who doesn't want to grow up, because even though death can take a little boy, it usually waits till later, after a fellow has lived a bit, and Holden knows that the farther he gets away from childhood the closer he gets to death.
While all of this is going on in the background of Holdens life, he is still a teenager, trying to wrestle with the problems that all teenagers wrestle with, problems that to a teenage mind loom larger than life and seem very dramatic, Holden has more problems than most, in fact he feels like one big problem compressed into human form and it's no coincidence that all these problems come to a head at one time and Holden cracks up again.
The story is a favorite among Teenagers, Holden is alone against all the troubles of the World, and most sensitive teens feel much the same. For the most part most teenagers are scared and confused, the sweet childhood years are gone, and will never come back, the life that replaces is completely different from childhood, the real world with all it's pressures arrives all at once, including the need to find a girlfriend or a partner that truly loves you, because if you don't you will be left all alone, but the same forces that design that young boy should die are also in charge of love and future fortune.
No wonder Holden is so scared.