Card doesn't shy away from depicting the brutal realities of war, even when fought for survival. Ender faces intense pressure, isolation, and manipulation, all in the name of becoming the ultimate weapon. The novel questions the ethical boundaries of warfare and the psychological toll it takes on those involved, especially children forced to confront unimaginable violence.

Despite being trained for combat, Ender displays a strong sense of empathy and a desire to understand his opponents. He questions the dehumanization of the buggers and grapples with the possibility of communication and peace. This theme explores the importance of understanding different perspectives and the potential for empathy even in the face of conflict.

Throughout his training, Ender is constantly manipulated by his teachers and superiors who use psychological tactics and controlled environments to mold him into the leader they need. The novel critiques the dangers of blind obedience and the ethical implications of manipulating individuals, even for a perceived greater good.