Why is Ruth so controlling? Her motivation

"...But there was no doubt she was the leader." Kathy Page 49
Every school has a girl like Ruth. She's a sort of queen bee who all the girls follow and listen to. She's controlling and some would even say a little bit of a bully. She has even been know to tell some white lies here and there. However, there are still times when Ruth genuinely seems like a good and caring person. For example she tries to help Kath find her tape without causing a scene. So why does she act so witchy? In truth I think the motivation behind her behaviors is that she is insecure and unsure about who she is. She is still young and on top of having what appears to be a very confusing and special entity, she also has the feeling of just wanting to be accepted and liked. She makes up certain things so she appear more cool or elite. Also she often acts like things don't both her so she keeps her cool and controlling image in tact. It also might stem from the fact that she really seems to have no control of her life. She always has to do what the guardians say and then her career and life path from here on out is already planned for her. So it seems right that she would want to control some aspect of her life.