Killua was wearing harem pants.
Well, not exactly. Gon stared at the pants for the thirteenth or fourteenth time that day - he'd lost count, not that it was important - trying to figure out just what it was about them. They were a smooth-looking material, and very loose, and they billowed at the bottom just like harem pants did.
"They're in style around here," Killua shrugged off his inquiry, and gave him a smug look. "Gon, you don't keep up with things, do you? Take a look around; everyone's got a pair. I thought I'd see what the big deal was."
The big deal was that the pants were mesmerizing. Gon had spent some time - not too much, of course, but as much as he could probably spare - staring at the lower part of Killua's body with fascination. They were loose pants, of course, but there was something about the material that made them slide just right around the line of Killua's hips, giving just the barest glimpses of what form his body took around there. And if you looked at his legs, the same sort of thing was happening there.
It was… it was amazing. Tight pants couldn't have given this much of a show. Gon didn't know how they did it. It must have been some crazy local secret, some kind of Nen put into them when they were made… something. Because twice since that morning, he'd just about walked into something while staring at Killua's rear end, and gotten a funny look from his friend in the process.
"They're comfortable, you know." Killua gave him an almost sly look from the corner of his eyes that night, as if he was holding back a smirk. "You should get a pair too, Gon." And then he wore them the next day as well.
Gon had thought he was getting used to the pants, but apparently the mystery was too great - the incredible quality of the pants was too much temptation. The more he stared, the more he wanted to keep staring, and the less he cared about local attractions. It was the pants that were the real attraction around here! He could hardly muster interest for the other things around them - whenever his mind wandered, his eyes went right back to the pants, as if drawn in by eye-magnets.
Maybe that's it…
"Can I see what they feel like?" he finally asked when they were sitting down back at their inn, determined to figure out the secret by any means necessary. "I want to know what they're made of."
Killua was giving him a thoughtful look - a calculating sort of look, really, with edges of interest. "I'm not taking them off just for that," he snorted, and stretched his legs out in front of him.
Gon ignored them. He knew what part of the pants was really important…
It was only some time later, after the point of the evening where they'd been naked and sweaty and moving against each other while their breathing had been ragged with excitement and desperation and pleasure, and Killua had been saying into his ear, "Gon, Gon, Gon," like it was a prayer, that Gon figured it out.
It wasn't really about the pants - it was about what happened when they were taken off.