The strong tendency to see ourselves (and some others) as victims, to feel wronged by another or others, to make ourselves or our group right (and the victim) and to make others wrong. But it goes deeper...because victimhood is based in the good/bad, right/wrong, should/shouldn't view of the world. Even when we blame ourselves, we have become the victim of ourselves. This tendency blinds us to looking at the facts, to discovering how we may have contributed to the situation, and to being curious how how we can best get what we want under the current circumstances (with blaming the other person or ourselves almost always being counterproductive). The victimhood bias shuts down our capability to assess the situation more accurately. It shuts down our creativity and our ability to possibly negotiate a collaborative solution.
In WWII, Japanese saw Americans and Chinese as the bad guys. Americans and Chinese saw the Japanese as the bad guys. Everyone was the victim. In the divorce between my parents, my mother saw my father as the bad buy and vice versa. They were both victims. In the disputes between the Republicans and the Democrats, they both see themselves as victims of the other. Whenever you are defensive, whenever you are resentful, whenever you feel taken advantage of, whenever you lack curiosity about the "bad" guy's behavior, whenever you feel guilty or regret, whenever you are willing to let go of some of your power and influence (by not being 100% responsible), you will be able to notice that you are a righteous victim (even if you are blaming yourself). And it's very addictive. It's been a lifelong process to undo this (mostly) in myself. See undoing shoulds and being 100% responsible.