In Vietnamese novel "The Sorrow of War" by Bảo Ninh, Kiên is a former soldier from the Vietnam War, haunted by memories of battle and lost comrades. His introspective and melancholic nature is deeply rooted in the trauma of war. Kiên's constant reflections on the past drive him to write, expressing his struggles with reconciling the present and his longing for the lost youth and camaraderie of wartime.