The man still hadn't spoken when Ender was ready and went to the door to leave the room. The door didn't open. Ender turned to face the man sitting on the floor. He looked to be about sixty, by far the oldest man Ender had seen on Eros. He had a day's growth of white whiskers that grizzled his face only slightly less than his close-cut hair. His face sagged a little and his eyes were surrounded by creases and lines. He looked at Ender with an expression that bespoke only apathy.

Ender turned back to the door and tried again to open it.

"All right," he said, giving up. "Why's the door locked?"

The old man continued to look at him blankly.

So this is a game, thought Ender. Well, if they want me to go to class, they'll unlock the door. If they don't, they won't. I don't care.

Ender didn't like games where the rules could be anything and the objective was known to them alone. So he wouldn't play. He also refused to get angry. He went through a relaxing exercise as he leaned on the door, and soon he was calm again. The old man continued to watch him impassively.

It seemed to go on for hours, Ender refusing to speak, the old man seeming to be a mindless mute.

Sometimes Ender wondered if he were mentally ill, escaped from some medical ward somewhere in Eros, living out some insane fantasy here in Ender's room. But the longer it went on, with no one coming to the door, no one looking for him, the more certain he became that this was something deliberate, meant to disconcert him. Ender did not want to give the old man the victory. To pass the time he began to do exercises. Some were impossible without the gym equipment, but others, especially from his personal defense class, he could do without any aids.

The exercises moved him around the room. He was practicing lunges and kicks. One move took him near the old man, as he had come near him before, but this time the old claw shot out and seized Ender's left leg in the middle of a kick. It pulled Ender off his feet and landed him heavily on the floor.

Ender leapt to his feet immediately, furious. He found the old man sitting calmly, cross-legged, not breathing heavily, as if he had never moved. Ender stood poised to fight, but the other's immobility made it impossible for Ender to attack. What, kick the old man's head off? And then explain it to Graff -- oh, the old man kicked me, and I had to get even.

He went back to his exercises; the old man kept watching.

Finally, tired and angry at this wasted day, a prisoner in his room, Ender went back to his bed to get his desk. As he leaned over to pick up the desk, he felt a hand jab roughly between his thighs and another hand grab his hair. In a moment he had been turned upside down. His face and shoulders were being pressed into the floor by the old man's knee, while his back was excruciatingly bent and his legs were pinioned by the old man's arm.

Ender was helpless to use his arms, he couldn't bend his back to gain slack so he could use his legs. In less than two seconds the old man had completely defeated Ender Wiggin.

"All right," Ender gasped. "You win."

The man's knee thrust painfully downward. "Since when," asked the man, his voice soft and rasping, "do you have to tell the enemy when be has won?"

Ender remained silent.

"I surprised you once, Ender Wiggin. Why didn't you destroy the immediately afterward? Just because I looked peaceful? You turned your back on me. Stupid. You have learned nothing. You have never had a teacher."

Ender was angry now, and made no attempt to control or conceal it. "I've had too many teachers, how was I supposed to know you'd turn out to be a--"

"Au enemy, Ender Wiggin," whispered the old man. "I am your enemy, the first one you've ever had who was smarter than you. There is no teacher but the enemy. No one but the enemy will ever tell you what the enemy is going to do. No one but the enemy will ever teach you how to destroy and conquer. Only the enemy shows you where you are weak. Only the enemy tells you where he is strong. And the only rules of the game are what you can do to him and what you can stop him from doing to you. I am your enemy from now on. From now on I am your teacher."

Then the old man let Ender's legs fall. Because he still held Ender's head to the floor, the boy couldn't use his arms to compensate, and his legs hit the surface with a loud crack and a sickening pain. Then the old man stood and let Ender rise.

Slowly Ender pulled his legs under him, with a faint groan of pain. He knelt on all fours for a moment, recovering. Then his right arm flashed out, reaching for his enemy. The old man quickly danced back, and Ender's hand closed on air as his teacher's foot shot forward to catch Ender on the chin.

Ender's chin wasn't there. He was lying flat on his back, spinning on the floor, and during the moment that his teacher was off balance from his kick, Ender's feet smashed into the old man's other leg. He fell in a heap -- but close enough to strike out and hit Ender in the face. Ender couldn't find an arm or a leg that held still long enough to be grabbed, and in the meantime blows were landing on his back and arms. Ender was smaller -- he couldn't reach past the old man's flailing limbs. Finally he managed to pull away and scramble back near the door.

The old man was sitting cross-legged again, but now the apathy was gone. He was smiling. "Better, this time, boy. But slow. You will have to be better with a fleet than you are with your body or no one will be safe with you in command. Lesson learned?"

Ender nodded slowly. He ached in a hundred places.

"Good," said the old man. "Then we'll never have to have such a battle again. All the rest with the simulator. I will program your battles now, not the computer; I will devise the strategy of your enemy, and you will learn to be quick and discover what tricks the enemy has for you. Remember, boy. 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."

The old man's face grew serious again. "You will be about to lose, Ender, but you will win. You will learn to defeat the enemy. He will teach you how."

The teacher got up. "In this school, it has always been the practice for a young student to be chosen by an older student. The two become companions, and the older boy teaches the younger one everything he knows. Always they fight, always they compete, always they are together. I have chosen you."

Ender spoke as the old man walked to the door. "You're too old to be a student."

"One is never too old to be a student of the enemy. I have learned from the buggers. You will learn from me."

As the old man palmed the door open, Ender leaped into the air and kicked him in the small of the back with both feet. He hit hard enough that he rebounded onto his feet, as the old man cried out and collapsed on the floor.

The old man got up slowly, holding onto the door handle, his face contorted with pain. He seemed disabled, but Ender didn't trust him. Yet in spite of his suspicion, he was caught off guard by the old man's speed. In a moment he found himself on the floor near the opposite wall, his nose and lip bleeding where his face had hit the bed. He was able to turn enough to see the old man standing in the doorway, wincing and holding his back. The old man grinned.

Ender grinned back. "Teacher," he said. "Do you have a name?"

"Mazer Rackham," said the old man. Then he was gone.

From then on, Ender was either with Mazer Rackham or alone. The old man rarely spoke, but he was there; at meals, at tutorials, at the simulator, in his room at night. Sometimes Mazer would leave, but always, when Mazer wasn't there, the door was locked, and no one came until Mazer returned. Ender went through a week in which he called him Jailor Rackham, Mazer answered to the name as readily as to his own, and showed no sign that it bothered him at all. Ender soon gave it up.

There were compensations -- Mazer took Ender through the videos of the old battles from the First Invasion and the disastrous defeats of the I.F. in the Second Invasion. These were not pieced together from the censored public videos, but whole and continuous. Since many videos were working in the major battles, they studied bugger tactics and strategies from many angles. For the first time in his life, a teacher was pointing out things that Ender had not already seen for himself. For the first time, Ender had found a living mind he could admire.

"Why aren't you dead?" Ender asked him. "You fought your battle seventy years ago. I don't think you're even sixty years old."

"The miracles of relativity," said Mazer. "They kept me here for twenty years after the battle, even though I begged them to let me command one of the starships they launched against the bugger home planet and the bugger colonies. Then they -- came to understand some things about the way soldiers behave in the stress of battle."

"What things?"

"You've never been taught enough psychology to understand. Enough to say that they realized that even though I would never be able to command the fleet -- I'd be dead before the fleet even arrived -- I was still the only person able to understand the things I understood about the buggers. I was, they realized, the only person who had ever defeated the buggers by intelligence rather than luck. They needed me here to-- teach the person who would command the fleet."

"So they sent you out in a starship, got you up to a relativistic speed--"

"And then I turned around and came home. A very dull voyage, Ender. Fifty years in space. Officially, only eight years passed for me, but it felt like five hundred. All so I could teach the next commander everything I knew."

"Am I to be the commander, then?"

"Let's say that you're our best bet at present."

"There are others being prepared, too?"

"No."

"That makes me the only choice, then, doesn't it'?"

Mazer shrugged.

"Except you. You're still alive, aren't you? Why not you?"

Mazer shook his head.

"Why not? You won before."

"I cannot be the commander for good and sufficient reasons."

"Show me how you beat the buggers, Mazer."

Mazer's face went inscrutable.

"You've shown me every other battle seven times at least. I think I've seen ways to beat what the buggers did before, but you've never shown me how you actually did beat them."