Displacement is one of many factors that contribute to bullying. Sometimes a bully may be the victim of abuse or violence at home, and he feels powerless to address his pain and anger. He then redirects that anger toward targets at school who are less threatening and powerful. This can lead to a cycle of aggression.
This pattern is not limited to childhood, and it can occur in adolescence and adulthood as well. For example, research suggests that displaced anger may be a contributing factor in gang violence.