or of woman. It is a philosophic idea that people have the potential for good and bad within them. That thought maybe that Descarte thought it up, but the Geeks and Hindus may have thought about it first.
Everyone has a dark side, some can hide it better than others. Every human is a sinner or at least thinks of sin, with the exception of Jesus and his mother Mary as Christianity teaches. All others fall short.
What is evil? Damion Thorne in "Omen 3: The Final Conflict" said that "Sometimes evil can be as pure as good." to a reporter. It is believed that people and animals can be born evil with an evil nature or evil personality. Yet still, somewhere inside them, is the potential to do good. The choice is up to them to decide. Some people choose evil by choosing to be selfish and only think of themselves and feel that rules and laws don't apply to them. A person like that may end up a rapist or a bank robber or a gangster. They are the dark types.
On the other hand, some people or animals are born good with good personalities. The potential for evil lies within them, and they must choose to do good or evil. Sometimes they do evil without thinking about it, it may be unintentional. They try to think of others, and do things for the common good. Mother Theresa and Lady Di and Pope John Paul II are examples of good people. People are drawn to good people because of the goodness within them. They are the light types.
There are people and animals that are mixed, both good and evil depending on the situation. These are the average people. Doing good one day and doing bad the next. Maybe helping someone out on Monday, and then cheating on their taxes on Tuesday. They are sitting on a fence trying to decide to be good or evil. Sometimes they just don't think about it and randomly do good and evil things. These are the grey types.
Now a dark type may resent a light type because their personalities clash. The light type may attract a dark type, and the dark type hates the light type and takes what he/she wants. In this case, a rape and murder.
Usually you can tell a dark type by the way they treat other people, most of the time anyway. Are they being mean to a waitress who is just doing her job? Are they yelling at somebody else for an accident that could have happened to anyone? If they treat other people this way, what about you? I've seen abusive relationships happen, and then the light person doesn't want to break up with the dark person. They just continue to take the abuse, when anyone else would have just walked out on the relationship. Not sure why but light is also attracted to dark. Scary.