Final answer:
Ender's one friend at Battle School is Alai, which is an important aspect of their bond in 'Ender's Game'.
Step-by-step explanation:
Ender thought his one friend at Battle School was Alai. The relationship between Ender and Alai is a significant element in Orson Scott Card's novel Ender's Game.
The bond they form at Battle School serves as a critical source of support and camaraderie for Ender in an environment that is otherwise quite hostile and isolating. Although Ender has interactions with other characters like Petra, Bean, and Bonzo, it is Alai who ultimately becomes his true companion during the early stages of his journey at Battle School, exemplified when they share a moment of friendship with the phrase "Salaam".