This is Charlie's story, through and through. His letters give us an intimate look into his life, his thoughts, his hopes, his fears, and his all-too-often fragile mental state.
And Charlie seems like an honest guy, doesn't he? But wait. Charlie isn't even his real name? He tells us right off the bat, "I will call people by different names or generic names because I don't want you to find me" (1.1.2). So how can we be sure that anything he's saying is true? How can we trust him?
Maybe we're just being paranoid (and no, it isn't because of Bob's brownies). But we have to admit—it's a little difficult believing everything Charlie says.