The Perks of Being a Wallflower Theme of Passivity

There's a fine line between shyness and passivity, and in The Perks of Being a Wallflower, Charlie skips back and forth across it like a jump rope. Sure, Charlie has rare moments of assertiveness, like when he approaches Patrick at the football game for the first time. And once he gets the ball rolling, he can run with it. But that works both ways, and when Charlie stops being social, he definitely puts the "inert" in inertia. He's lucky he has Sam and Bill, who try to temper his shyness and get him to participate in, well, anything and everything.

1. Is Charlie passive aggressive or just plain passive? Is one better than the other?
2. What prompts Charlie to act when he does? Do you think these moments are exceptions to the rules, or is he growing as a person?
3. What are the consequences of Charlie's passivity?
4. Are there benefits to Charlie's inaction?