Didn't matter. Couldn't think about that. Because Bean knew that along with his primary assignment as one of the squadron chiefs, he had another, deeper work to do. He had to watch the whole flow of each battle, ready to step in at any moment, should Ender falter. Ender seemed not to guess that Bean had that kind of trust from the teachers, but Bean knew it, and if sometimes it made him a little distracted in fulfilling his official assignments, if sometimes Ender grew impatient with him for being a little late, a little inattentive, that was to be expected. For what Ender did not know was that at any moment, if the supervisor signaled him, Bean could take over and continue Ender's plan, watching over all of the squadron leaders, saving the game.

At first, that assignment seemed empty – Ender was healthy, alert. But then came the change.

It was the day after Ender mentioned to them, casually, that he had a different teacher from theirs. He referred to him as "Mazer" once too often, and Crazy Tom said, "He must have gone through hell, growing up with that name."

"When he was growing up," said Ender, "the name wasn't famous."

"Anybody that old is dead," said Shen.

"Not if he was put on a lightspeed ship for a lot of years and then brought back."

That's when it dawned on them. "Your teacher is the Mazer Rackham?"

"You know how they say he's a brilliant hero?" said Ender.

Of course they knew.

"What they don't mention is, he's a complete hard-ass."

And then the new simulation began and they got back to work.

Next day, Ender told them that things were changing. "So far we've been playing against the computer or against each other. But starting now, every few days Mazer himself and a team of experienced pilots will control the opposing fleet. Anything goes."

A series of tests, with Mazer Rackham himself as the opponent. It smelled fishy to Bean.

These aren't tests, these are setups, preparations for the conditions that might come when they face the actual Bugger fleet near their home planet.

The I.F. is getting preliminary information back from the expeditionary fleet, and they're preparing us for what the Buggers are actually going to throw at us when battle is joined.

The trouble was, no matter how bright Mazer Rackham and the other officers might be, they were still human. When the real battle came, the Buggers were bound to show them things that humans simply couldn't think of.

Then came the first of these "tests" – and it was embarrassing how juvenile the strategy was. A big globe formation, surrounding a single ship.

In this battle it became clear that Ender knew things that he wasn't telling them. For one thing, he told them to ignore the ship in the center of the globe. It was a decoy. But how could Ender know that? Because he knew that the Buggers would show a single ship like that, and it was a lie. Which means that the Buggers expect us to go for that one ship.

Except, of course, that this was not really the Buggers, this was Mazer Rackham. So why would Rackham expect the Buggers to expect humans to strike for a single ship?

Bean thought back to those vids that Ender had watched over and over in Battle School – all the propaganda film of the Second Invasion.

They never showed the battle because there wasn't one. Nor did Mazer Rackham command a strike force with a brilliant strategy. Mazer Rackham hit a single ship and the war was over. That's why there's no video of hand-to-hand combat. Mazer Rackham killed the queen. And now he expects the Buggers to show a central ship as a decoy, because that's how we won last time.

Kill the queen, and all the Buggers are defenseless. Mindless. That's what the vids meant. Ender knows that, but he also knows that the Buggers know that we know it, so he doesn't fall for their sucker bait.

The second thing that Ender knew and they didn't was the use of a weapon that hadn't been in any of their simulations till this first test. Ender called it "Dr. Device" and then said nothing more about it – until he ordered Alai to use it where the enemy fleet was most concentrated. To their surprise, the thing set off a chain reaction that leapt from ship to ship, until all but the most outlying Formic ships were destroyed. And it was an easy matter to mop up those stragglers. The playing field was clear when they finished.

"Why was their strategy so stupid?" asked Bean.

"That's what I was wondering," said Ender. "But we didn't lose a ship, so that's OK."

Later, Ender told them what Mazer said – they were simulating a whole invasion sequence, and so he was taking the simulated enemy through a learning curve. "Next time they'll have learned. It won't be so easy."

Bean heard that and it filled him with alarm. An invasion sequence? Why a scenario like that? Why not warmups before a single battle?

Because the Buggers have more than one world, thought Bean. Of course they do. They found Earth and expected to turn it into yet another colony, just as they've done before.

We have more than one fleet. One for each Formic world.

And the reason they can learn from battle to battle is because they, too, have faster-than-light communication across interstellar space.

All of Bean's guesses were confirmed. He also knew the secret behind these tests. Mazer Rackham wasn't commanding a simulated Bugger fleet. It was a real battle, and Rackham's only function was to watch how it flowed and then coach Ender afterward on what the enemy strategies meant and how to counter them in future.

That was why they were giving most of their commands orally. They were being transmitted to real crews of real ships who followed their orders and fought real battles. Any ship we lose, thought Bean, means that grown men and women have died. Any carelessness on our part takes lives. Yet they don't tell us this precisely because we can't afford to be burdened with that knowledge. In wartime, commanders have always had to learn the concept of "acceptable losses." But those who keep their humanity never really accept the idea of acceptability, Bean understood that. It gnaws at them. So they protect us child-soldiers by keeping us convinced that it's only games and tests.

Therefore I can't let on to anyone that I do know. Therefore I must accept the losses without a word, without a visible qualm. I must try to block out of my mind the people who will die from our boldness, whose sacrifice is not of a mere counter in a game, but of their lives.

The "tests" came every few days, and each battle lasted longer. Alai joked that they ought to be fitted with diapers so they didn't have to be distracted when their bladder got full during a battle. Next day, they were fitted out with catheters. It was Crazy Tom who put a stop to that. "Come on, just get us a jar to pee in. We can't play this game with something hanging off our dicks." Jars it was, after that. Bean never heard of anyone using one, though. And though he wondered what they provided for Petra, no one ever had the courage to brave her wrath by asking.

Bean began to notice some of Ender's mistakes pretty early on. For one thing, Ender was relying too much on Petra. She always got command of the core force, watching a hundred different things at once, so that Ender could concentrate on the feints, the ploys, the tricks. Couldn't Ender see that Petra, a perfectionist, was getting eaten alive by guilt and shame over every mistake she made? He was so good with people, and yet he seemed to think she was really tough, instead of realizing that toughness was an act she put on to hide her intense anxiety. Every mistake weighed on her. She wasn't sleeping well, and it showed up as she got more and more fatigued during battles.

But then, maybe the reason Ender didn't realize what he was doing to her was that he, too, was tired. So were all of them. Fading a little under the pressure, and sometimes a lot. Getting more fatigued, more error-prone as the tests got harder, as the odds got longer.