If Alai were a TV character, his catch-phrase would be “Salaam,” which is Arabic for “peace.” Since these kids are in Battle School to learn war, this is ironic and awesome. However, when Alai kisses Ender and whispers this to him, he suddenly turns embarrassed; Ender wonders if it has to do with a “suppressed religion” or if it’s just super private (7.58). This is probably Alai’s most important moment and a pretty good expression of his character: for a kid who prepares for war, what embarrasses him is his wish for friendship and peace.
Let’s take a step back and remember that Ender really befriends Alai as a way to take power away from Bernard. See, Bernard and Alai are friends, but once Ender and Alai start playing around, the power dynamic in the group shifts away from Bernard. So in some ways, even the friendship between Ender and Alai is part of a war (against Bernard).
But even if it starts out as a manipulative move, the friendship between Ender and Alai grows to be genuine. Whenever Ender gets close to Alai, he thinks about his sister and his mom, so Alai is kind of a replacement for his family. When Ender is about to give up, Alai gives him hope to carry on (at least, that’s what happens when Ender is transferred to Salamander Army).
Of course, since nothing ever works out for Ender, he and Alai drift apart, especially since Ender is advanced very quickly. But still, Ender retains his memories of Alai, and Alai becomes one of his squadron leaders when he fights the buggers.