How do the relationship with one peer group determine the kind of person they became?

they manipulate the people in the group so basically when they say or do something the person that its being directed at so make the people happy in this group the person wants to make them happy so they pick up on the way the others treat another sometimes with out knowing it the newest member ends of treating the person that they target is treated the same way the group treats that person in order to stay a friend in that group it can get so bad that the new person may not realize what their doing and be in denial saying i'm nutrail i would never do that knowing their not they keep up with this behavior