#settingdescriptions

In the last two letters that Charlie writes to his "friend", he talks about a near-sexual encounter with Sam, which brings up bad memories of him and his Aunt Helen. After he stops Sam and he goes to bed that night, he has a dream of his Aunt Helen doing the things to him that Same was doing earlier that day. This dream was actually reality, and the remembrance of his Aunt Helen molesting him put him into an emotional, mentally dysfunctional state which caused him to be hospitalized for two months. 

Later on throughout the book, Charlie is taken to several other parties, where he is introduced to drugs such as ecstasy. 

The Perks of Being a Wallflower is based on letters due to Charlie's fear of highschool. His year at highschool is how he makes new friends, how he develops new habits, and how he blossoms from being a wallflower to an outgoing teenager.