Ender's Game Chapter 14: Ender's Teacher
The center of his training on the asteroid was a simulator. The computer was very intelligent and adapted to Ender as quickly as he did to it. However, he became its master during his first year there, able to command everything from a single ship to an entire fleet with ease, and winning. Ender asked Graff one day why the game isn't getting harder anymore. Graff seemed unconcerned and disappeared the next day.
In his place was an old man who tells Ender that his mind better be sharper with the simulator than he is with his body. "I will program your battles now, not the computer... From now on the enemy is more clever than you. From now on the enemy is stronger than you. From now on you are always about to lose... but you will win. You will learn to defeat the enemy." Chapter 14, pg 263-4 When asked his name, the old man responds that he is Mazer Rackham (hero of the Second Bugger War of seventy years before).
Rackham had been sent away on a lightspeed ship and brought back at verge of the Third Invasion. Relativity allowed only eight years to pass for him, while fifty years passed for everyone else. People realized only Mazer Rackham could teach the next leader how to think against the Buggers, because he won due to intelligence, not luck.
They discussed battles with the Buggers, and Ender explains what he knows of Mazer's victory - a few ships against the Bugger fleet, they attack one ship, it explodes, and then nothing. Mazer says that exactly that happened. He explained that the Buggers are still insects - they function as a hive, but at a higher level. They communicate from mind to mind. In fact, the queen of this hive has so much control, Mazer reasoned, that she controls the hive the way a human controls his or her own body. Every Bugger was like a hand or foot. Mazer then proved it by replaying the battle, and Ender saw that every decision was made from a self-aware center.
Mazer turns to strategy. Humanity's weakness of lack of single purpose is its strength - each ship has an intelligent thinking commander. In addition, Mazer explains, the Dr. Device is more powerful weapon than anything the Buggers have.
Ender is to be the commander, and to train squadron leaders. They turn out to be all the students at Battle School whom he recognized as excellent or respectable, including Bean, Petra, Dink, and many others. They train together and Ender learns their strengths and weaknesses on this simulator. They worked together seamlessly. Under Mazer's exercises, Mazer explained, Ender will be forever outnumbered.
Mazer then says the final stage of his training will begin - a full invasion scenario. At first, it will be easy, at the outskirts of Bugger-controlled space, but it will quickly become harder as Mazer will program each successive battle. Mazer's goal is to break Ender, and Ender responds that he won't be broken.
The battles begin easy, and quickly become harder - the enemy would undoubtedly learn from Ender. Mazer debriefs with Ender after each battle. Battles happen at all hours, with little or no sleep, and Ender is expected to the best job he could. Ender feels more isolated than ever, never being able to see his friends and interacting only with a simulator or Rackham. Ender becomes a relentless trainer of his army, and the friendships give way to a command structure, only further isolating Ender. Excellence is his goal, and they battle often.
Ender's psyche begins to respond to the pressure - he has nightmares, calls out in his sleep, his body can only handle bland foods, he gnaws at himself in his sleep, and becomes completely isolated. His dreams blend the Fantasy Game's Giant with the Buggers. His squadron leaders start to falter - Petra, whom he had leaned upon the most, stops functioning, and a battle is nearly lost. He now has to take into account their fatigue and ignore his own even more.
Ender takes the simulations deadly seriously, no doubt influenced by the dire tone of his dreams. Mazer respond that Ender is only playing games. Mazer responds, "Strange dreams are a safety valve, Ender. I'm putting you under a little pressure for the first time in your life." Chapter 14, pg 287
His body finally gives up during practice, and he blacks out. He thinks he hears Graff and Mazer both saying they love him, and that the trial is almost over, but then they turn into Valentine and Alai.
The final test comes after Ender is recovered. There are adults in the audience of this final test. There is one new wrinkle - there is a planet. This is the simulated end of an invasion. Ender would be ready to be a commander if he can pass this final test. Mazer reiterates that he is not going to coddle Ender, and the odds are probably overwhelmingly against him.
Ender asks Mazer if Dr. Device works against a planet. Mazer coldly responds that the Buggers never knowingly attacked civilians.
Ender's fleet is composed of less than a hundred old, slow, poorly-armed fighter. And the odds are a thousand-to-one. It was like the final battle at Battle School, the teachers stacked the deck against too far this time. Ender decides to give up. He will be free of their games once and for all. As strategy, he sends the ships into the swarming mass of "Bugger" ships. Only fourteen of eighty fighters remain, at the other side of the main enemy contingent, near the planet.
The enemy closes off the ships' escape from the planet, because Ender, until this point in his training, tried to preserve every ship. The ships then went for the planet. Once within range, he would set the Dr. Device off and destroy everything. The enemy realized too late what was happening, and then started destroying the ships one by one. Nonetheless, it was too late, the planet, and everything near it, bubbled and exploded. Ender had beat his teachers.
His squadron erupted in cheers, and Ender realized that his audience did too. Graff hugs Ender, and Mazer congratulates him. " 'You beat them, and it's all over.' All over. Beat them. Ender didn't understand... 'Ender, you never played me... This was the Third Invasion... the battles were real and the only enemies you fought were the buggers.'" Chapter 14, pg 296
Ender did not want to kill them. He wanted to be deemed unfit for command. Graff explains he had to be tricked, because they needed someone as compassionate as Valentine to think like the Buggers, and someone as brutal as Peter to completely destroy them.
Earth is chaos - the main reason for unity has been destroyed, and everyone is wrangling for supremacy. Ender shuts down, and finally awakes to his friends, in person, for the first time. He is melancholy, but relieved to have friends.