People can be both victims and perpetrators at the same time. In fact, we all are to some degree.

Everytime you hurt someone, even on accident, it has the chance of leaving a real impact on that person. The impact that you have on them then has an effect on how that person treats others. Abusers are often victims of abuse. It's a cycle of being hurt and hurting others, even in small ways that may not have been intentional at all. This is a fact of life.

Living as if any person or any group is solely either the victim or the perpetrator is simply wrong. It's so obviously wrong that grown adults instinctively recognize it as wrong when they see one-dimensional characters presented in fiction. Children don't see these types of characters as one-dimensional because they don't yet understand the contradictions inherent in human nature, but anyone who has matured beyond childhood instinctively recognizes the contradictory nature of being a human being.