Revenge is a major theme in Elliot Ackerman’s debut novel “Green on Blue.” The novel is told from the point-of-view of an Afghan boy named Aziz who’s seeking to avenge his brother Ali. It may seem strange to have an American tell the story of an Afghan boy, especially when that American served in the military in Afghanistan. But Ackerman told Rehman Tungekar that fighting in Afghanistan is what compelled him to tell the story this way.