Why would the Fritz be the Antagonist in the story Three Day Road?

In "Three Day Road" by Joseph Boyden, Fritz serves as an antagonist due to his embodiment of the destructive aspects of war and the loss of humanity it brings. He represents the harsh realities of the battlefield, influencing the main characters, particularly Xavier and Elijah, as they confront the moral dilemmas and psychological traumas of conflict. Fritz's character challenges their identities and relationships, highlighting the darker side of camaraderie and survival during World War I. His presence ultimately forces the protagonists to grApple with their own values and the consequences of their choices amidst the chaos of war.