Alai suddenly kissed Ender on the cheek and whispered in his ear. "Salaam." Then, red faced, he turned away and walked to his own bed at the back of the barracks. Ender guessed that the kiss and the word were somehow forbidden. A suppressed religion, perhaps. Or maybe the word had some private and powerful meaning for Alai alone. Whatever it meant to Alai, Ender knew that it was sacred; that he had uncovered himself for Ender, as once Ender's mother had done when he was very young, before they put the monitor in his neck, and she had put her hands on his head when she thought he was asleep, and prayed over him. Ender had never spoken of that to anyone, not even to Mother, but had kept it as a memory of holiness, of how his mother loved him when she thought that no one, not even he, could see or hear. That was what Alai had given him: a gift so sacred that even Ender could not be allowed to understand what it meant.I love the idea about why Ender's mother's love and Alai's gift of himself is so sacred.
Orson Scott Card, Ender's Game