The next day he passed Alai in the corridor, and they greeted each other, touched hands, talked, but they both knew that there was a wall now. It might be breached, that wall, sometime in the future, but for now the only real conversation between them was the roots that had already grown low and deep, under the wall, where they could not be broken.

The most terrible thing, though, was the fear that the wall could never be breached, that in his heart Alai was glad of the separation, and was ready to be Ender's enemy. For now that they could not be together, they must be infinitely apart, and what had been sure and unshakable was now fragile and insubstantial; from the moment we are not together, Alai is a stranger, for he has a life now that will be no part of mine, and that means that when I see him we will not know each other.

It made him sorrowful, but Ender did not weep. He was done with that. When they had turned Valentine into a stranger, when they had used her as a tool to work on Ender, from that day forward they could never hurt him deep enough to make him cry again. Ender was certain of that.

And with that anger, he decided he was strong enough to defeat them--the teachers, his enemies.