ok, i see.
think of it like this.
Person A. Has an equaly light a dark nature. But they never go to either of the extremes and they never really do much at all. The worst thing they are capable of is equal to the best thing. So as they are of no impact to anything.
Person B. Has an equaly light and dark nature. They are so extreme that they may go to extreme lengths to love and cherish one as pect of existence while happily letting the extreme of their dark/bad side murder or rape.
Person C. Has an equaly light and dark nature. They are moderate. They donate to charity but they also excesively punish their dog. This is the average person. Trying to do as many good things as possible but generally always having shortcoming of their own that create bad behaviour. We all try to pretend we have more good than bad but it often works about about even.
Person D. An exception Where they are perfectly good or perfectly bad without a known opposite nature. Sometimes just because the opposite nature is not visible perhaps, other times a genuine expection to the law.
see what im saying?