> it is quite another to allow others to derive some sort of satisfaction from that punishment

I sometimes see this behavior in close friends, and it totally changes the way I see them. I don't know if it's a moral failing on their part, but I just don't experience the desire for vengeance the same way they do, and it really scares me to see how they experience it. What will they do when they start to have mental decline, and (incorrectly) decide they were wronged in some way? :(