Mark is good at reading and manipulating people. Jeff is very easily influenced. Sue, like many other girls her age, is very naieve. Some girls will do anything to fit in/be accepted by a guy they like. That leads me to believe that she will probably do what they are going to ask. Have you'll noticed any other striking character traits?

Mark is very convincing and can make people do what he wants them to do and jeff has a temper.

Betsy doesn't really like the things her friends do but she stays with them and tries to fit in. You can tell she doesn't like the plan to kidnap Mr. Griffin but she goes along with them anyway.

Pretty much everyone in Mark's group is very easily swayed. Most people wouldn't just decide to kill their teacher after talking about it for 10 minutes. And if David gets Sue to help by pretending to like her, he's a real jerk

David is really responsible, and I think Betsy is very spoiled, she is used to always getting her way, and being liked by everyone.

I agree, but mark is seemingly going to grow up to be a serial killer, maybe even as feared as the zodiac, who died recently, thank goodness, because he can very easily twist the minds of everybody around him, not only giving him alibis, but cover from the law, lots of henchmen, so on, so forth, which is a very disturbing thought to me, VERY disturbing..... (i think i just had chills.)

David seems like a very nice, popular normal boy. When chapter four rolls around though he seems very sneaky. I didn't see any other part in the book where David liked Susan up until Chapter four where, coincidently, they're trying to get her to help them. Although David seems innocent, I don't think he is.

Why do you think she would do that?

David is easy to concivce once you point out things about his life he doesn't like example: when mark convices him at his house to kidnap Mr. griffin