One year, when they go back to Whale Island for a visit, things aren't quite the same as every other year. Sure, there's the same food on the table, the same faces to smile at, the same forest to explore over and over and the same room to sleep in at night. But on this visit--when their voices have both dropped and between them, they've grown nearly two feet in a year--Mito-san has people she wants them to meet. Girls their age that she invites over to dinner. Killua scowls and sulks and is rude to the girls. Gon can't figure out what it going on. Until suddenly he does, and then he is nice to the girls to make up for Killua being so mean, and Killua storms out. After dinner Gon tells Mito-san thank you but he and Killua are really not ready for that sort of thing.
Later that night, when Gon is almost asleep, Killua whispers something to him. Or maybe he whispers it to himself, maybe he thinks Gon is sleeping. "Gon, don't ever love a girl like that more than me. Don't ever love someone more than me." He whispers it so quietly that Gon can barely make the words out. Then, while Gon is still deciding whether or not to reply, Killua falls asleep.
Time passes. They stop growing; they start shaving. They search for Gon's father with waning vigor, and get tangled into their friends' adventures on a regular basis. They have been to nearly a third of the countries in the world. They decide to take a break and go home again, and when they get there Mito-san hasn't listened to what Gon asked. She invites girls over for dinner again. This time, Killua is not rude and Gon is not nice. They are both very quiet. Gon knows the girls are amiable and attractive, but he can't help wishing very hard that they would just go away. After dinner Mito-san tells the boys to walk the girls home, and Gon realizes they really ought to, so they do. He's never been so reluctant to do something he knew was the right thing before. He's afraid that Killua will start being rude again, but Killua says nothing, just trudges along with his hands in his pockets looking at the road. Gon doesn't know what to say. The girls talk to each other. They are all very grateful when they can say goodbye.
On the way home, Gon and Killua walk in silence at first. Then, after looking at Killua out of the corner of his eye, Gon starts haltingly to talk about where he thinks they might find their next clues to Gon's father's whereabouts. Slowly, the tension eases out of Killua's shoulders, and he responds with more and more willingness. By the time they get home they are fine again; they decide, without asking each other, to spend the rest of the evening in sparring practice to prevent Mito-san from speaking to them.
That night, Gon doesn't go to sleep. He lies on his back for hours listening to the sound of the wind and the tree branches and Killua not sleeping, wondering if Killua will say anything. When he does, it is a whisper, a shallow breath of air escaping from lungs that want for it. "Gon." Just that barest whisper, like something kept close and cold. "Don't ever love someone like that more than me." There's more to it. Gon has known that ever since their last visit, when Killua first said it. So he waits, and eventually the rest comes, so quiet he has to strain to hear it. "She couldn't ever love you more than I do."
Later, after Killua has fallen asleep, Gon decides that he can't put most of what is happening into words. It's too confusing. He doesn't know what the right thing to do is. To say something to Killua; to talk to Mito-san about the girls again; to say nothing to anyone, and lie here thinking and listening to Killua breathe. Part of him wants to ask how Killua can doubt. But part of him knows that what Killua is talking about is not the way Gon loves other people. Part of him wonders how you know--when you feel that way, when it's time, what's right. Gon doesn't know what "right" feels like; he just knows that some things feel very, very wrong. Like walking those girls home after dinner.
Eventually, he turns and rolls off his bed, onto Killua's cot--very normal, they both still tend to thrash around a lot during the night. "I wouldn't ever do anything that stupid," he whispers. Maybe Killua hears him, maybe not. Gon doesn't expect an answer. He falls asleep with his head nestled against the back of Killua's neck.
He knows by the way Killua looks at him when they get up the next morning that he heard. Neither of them mentions it. They go on with their visit as usual, and somehow by keeping strange hours and going camping a lot they manage, through unspoken conspiracy, to keep Mito-san from inviting the girls back.
More time passes, with more travels, more adventures. Things are a little bit different, but not much. They don't really talk about it. Every so often, when they've gone to bed but neither of them is asleep yet, one of them will hold out his hand and the other will take it. Sometimes they accidentally fall asleep with their fingers still loosely entwined; sometimes they accidentally yank each other out of bed. They are more at ease with each other than they have ever been.
Summer comes, and they visit Whale Island. They get the welcome-home dinner they are accustomed to, and to them, everything is exactly the same as it ever was. But unbeknownst to them, something about the way they sit next to each other has changed. Something about the way they finish each other's sentences is not how it used to be. The way they interrupt each other and remind each other of past events and jostle each other for space and ask each other for the salt--all of it speaks of possession, of being possessed. Mito-san looks at them long and hard that evening; alone in her room that night she looks out the window at the moon, thinking, before giving a short, decisive nod. She does not invite girls over again.