Final answer:
Ender Wiggin reacts with shock, betrayal, and guilt upon learning that the simulator used for his training was actually controlling real battles which led to the genocide of an alien species.
Step-by-step explanation:
Ender Wiggin, the protagonist in the science fiction novel Ender's Game by Orson Scott Card, experiences a powerful shock when he learns the truth about the simulator. Throughout his rigorous training at Battle School, Ender believes he is engaging in complex simulations to prepare for the real battle against the Formics, an alien species. However, when the final test is revealed to be an actual battle and not a simulation, Ender is overwhelmed by feelings of betrayal, guilt, and anger upon realizing he has unknowingly committed genocide.
His reaction is a critical point in the novel, representing a massive shift in his perception of himself, the adults who manipulated him, and the complexity of war. This moment also serves as a commentary on the morality of using young, talented individuals to accomplish military goals without their informed consent. Ender's deep emotional turmoil, sense of isolation, and the moral implications of his actions become significant themes that propel the story to its conclusion and set up the narrative for the subsequent novels in the series.