In Dubus's "Killings," Poe's "The Cask of Amontillado," and Kovite's "When Engaging Targets, Remember," what subject do all three of these literary pieces have in common?

All three of these short stories are about the reasons that men kill other men. Andre Dubus’s “Killings” is concerned with a father who takes revenge on the man who killed his son. Although this means he partakes of the same crime, his motivation is paternal love, whereas the other man was jealous. In “The Cask of Amontillado,” Edgar Allan Poe crafts a tale of a fiendish killer whose motivation is never quite revealed; while he clearly believes the man he kills had wronged him, we do not learn what his affronts were. The third story, by Gavin Kovite, is concerned with war. The protagonist of “When Engaging Targets, Remember" is a soldier who must distinguish between friend and foe. While he would prefer to rely on the official way of doing things, as laid out in the Rules of Engagement manual from which the title quotes, he desperately needs to be flexible and improvise.