Within "The Catcher in The Rye" there are many stereotypes. Holden himself is the introverted outsider who provokes people but is unable to finish his various crusades. He is surprisingly both mature and immature. His objectivity gives him an air of maturity, while his pesky personal opinions make the reader want to slap him for being such a hypocrite. He continuously bashes "phonies" while inadvertently behaving like one himself through his many lies and personality contradictions. His personality seems to be both complex and simple. Most simply, he is an opinionated hypocrite. More complexly put, he is a boy who seems normal enough except for the loud cries that he isn't; he is quiet, but audacious enough to just jump on his roommate and put him in a head lock. Holden Caulfield is a strange character in these ways. He appears at first sight of the reader to be the regular angst ridden adolescent narrator of a first person narrative. And he is, but with the maturity of looking back on his experiences and the voice of the overcompetent JD Salinger.
In addition to Holden, Ward Stradlater, his cocky, arrogant roommate is the epitome of a big headed adolescent boy. In many novels, stereotypes are such extremities that they accomplish their purpose with the reader either loathing or loving, identifying with or dismissing. Stradlater is this stereotype. He is oversexed and annoying yet charming. Always trying to give girls the "time" to use a definitely dated expression, Stradlater cares for none but himself and makes the reader dislike him for being himself. I am sure that if the book were told from Stradlater's perspective, we would identify with him as a source as we do Holden. Since we are learning about Stradlater from Holden who has proclaimed himself to both hate Stradlater and to be a terrible liar, the reader will always wonder what the real story is.
If Holden is the outsider and Stradlater the self absorbed character, then Robert Ackley is the oaf. From the way in which Holden describes him, Ackley is the boy everyone hates and pities. He also has a bit of an attitude and repeatedly bursts into Holden's room acting like he owns it. Ackley is the difficult one, the classic bully. His bully attitude is not totally who he is as is briefly revealed to the reader when Holden comes into his room in the middle of the night. Through the oafish exterior comes a goofy, sleepy Ackley who seems in a sick sense to almost care for Holden after Holden says that he fought Stradlater because Stradlater had made a bad comment about Ackley.
Both Ackley and Stradlater, though moreso Stradlater, act as catalysts of sorts to Holden's imminent loss of his grip on life. It can be seen that Holden is on the edge of a cliff where little things seem to crush him as the big picture gets lost. All Holden needs at this point is a tap on the shoulder and he will be sent careening over the edge.