What pivotal role does Holden play in the Catcher in the Rye?

As the main character, Holden and his teenaged "angst" form the focus of this novel. He finds himself completely alienated from his family and misses his brother desperately after that brother dies. He seems only to relate to his sister Phoebe who loves him but does not want him to leave. His being sent to a mental institution is his parents' only way of handling him after the death of the brother; he becomes basically a "dropout" from educational institutions and tries to act older when he is, in fact, a confused teen.