When Gon says, "I love you," for the first time, it comes out less as a confession as it does a matter of fact. He says it like he's breathing, like the words just slipped out of his lungs. "I love you," he repeats, and the sound is full of light.
Killua flushes, but does not turn away. He feels the red creep up the line of his neck, and he stammers, a small smile on his lips:
"Aa." He tugs at a strand of hair, embarrassed. Nervous. After a beat, he adds, "Cool beans."