Killua wasn't entirely sure how "collapse against each other in relief" had become "make out frantically against a wall", but under the circumstances, he didn't feel up to complaining.
The battle had been short, intense, and one-sided; he and Gon were lucky to escape with their lives, and he was sure both of them knew it. There were too many, coming too fast, and the chase had been altogether too close; the fact that they'd found the cave, and that they hadn't been discovered within it, was really just a stroke of fantastic luck.
He'd been scared. Terrified. His heart was still pounding hard; his muscled were tense; his skin prickled. Gon was too; he could feel it in the way he was holding himself and how his movements were. All in all, that had been one of the more frightening episodes of Killua's life.
Barely a couple of minutes later, and he was so turned on he could hardly stand it, pressing Gon against the wall and clinging to him tightly, mouths melded, bodies grinding together, rough and graceless and without finesse or thought or knowledge. They were going to have sex in some way or another, Killua knew that for fact, although separating his emotions from his more base needs at the moment was beyond him. Something about the fear had sparked this need, or maybe it had been there already and just needed some intense feeling to blend into it. Either way, as he slid slightly shaky fingers under Gon's clothing and felt Gon's hands move jerkily against him in answer, it was going to happen.
They could sort it out afterwards; right now, they were alive and together and probably just couldn't help reveling in it.