It’s interesting that so many storylines, some of the most compelling ones in fact, are centered on getting back at another person or another team, mostly out of competitive spirit. This feeling can obviously be experienced vicariously; the dopamine reaction fans feel when their sports team defeats the rival, who barely beat them last time on a technicality, is sweet indeed. Stories about avenging angels who retaliate on behalf someone else who was wronged are also popular. Luckily, for entertainment purposes, there are many opportunities for retaliatory-satisfaction in almost every situation; but once competitiveness slides into wishing someone harm in response, that’s revenge.

Revenge is perverse: animals don’t seek revenge; there is no competitive advantage for such an expense, but humans use revenge as motivation, a very powerful one that can easily become counter-productive. What makes it dangerous is that a person's self-image is often directly tied to what others think of them; people want admiration but will settle for respect, and if some person or group damages that fragile sense of self-worth, the recipient will be incensed and seek retribution, tearing the fabric of society to do it. Revenge is both nature and nurture.