Compare Charlie with Holden Caulfield.

Charlie is the protagonist of The Perks of Being a Wallflower (1999). Holden is the central character in The Catcher in the Rye (1951). 
What do these two characters have in common? Quite a lot, though there are also key differences (like the fact that Charlie lives in the suburbs of Pittsburgh, while Holden lives in New York City. These environments shape their lives and experiences: Charlie is more sheltered than Holden).
Let's go over some of the key similarities. 
They're both teenage boys.
Charlie is 15 when the story begins; Holden is 16 when his story begins.
They've both endured trauma.
There are several events we could mention here, but both characters have lost important figures in their lives. Holden's older brother, Allie, is dead, and Charlie's best friend committed suicide.
They're both navigating the border between childhood and adulthood.
Holden is anxious to grow up; in fact, he feels he already is grown up in certain ways. He's tall and already has a few gray hairs. He's interested in the adult world, including the idea of sex. Charlie isn't quite as advanced. He's a "wallflower," and he's the youngest in the family. But he was drawn to books that his aunt gave him, even though they were above his reading level at the time, and he has a good relationship with his older brother, which helps pave the way for his transition to adulthood.
They're both troubled by sexual encounters. And they both "crash." 
At the end of the book, after a sexual encounter with a girl he likes, an encounter that brings up repressed memories of sexual abuse he suffered through when he was a child, Charlie breaks down. His parents find him in a catatonic state, and he's taken to a mental hospital.
As for Holden: after a confusing encounter with Mr. Antolini, an English teacher that he admires, Holden spends the night in a state of despair in Grand Central Station. Later, in the epilogue of the book, he refers to having had a mental breakdown, though he also hints at his own recovery.