Today, Killua was acting weird. Werider than usual. He was talking less and less, and eventually stopped talking all together except for grunts and snarls. He had taken to curlingup on the floor instead of lounging around in his usual spot infront of the computer. His eyes were dilated all the time. Gon had given him chocolate in hopes of making him act normal, but Killua just grabbed the chocolate with his teeth and ran on all fours into his room, locking the door and not coming out. Gon was worried. Was his best friend in the world mad at him? Was he sick?
He asked Leorio ad Kurapika for help, explaining the situation.
"Maybe he's just on his period," wondered Leorio. "He's always craving chocolate."
"Leiorio-san, what is a period?"
Kurapika hit Leorio on the head and Gon did not know why. Now they were having their married people's quarrel, with a bunch of words Gon did not understand. 'Maybe those are just Kurta clan words haha,' Gon thought.
Then he remembered Killua. Maybe if he just walked into the room he could ask what was wrong? Gon decided to risk it. He had to know what was wrong!
Gon approached the door of the room Killua was currently hiding in. He put his hand on the doorknob, only to be shocked immensley, throwing him back to the wall. Bewildered, Gon rubbed his head and approached the door again. Using Gyo, he realized that Killua had infused the doorknob with his own electric aura. The doorknob buzzed with blue threads of electricity. 'He doesn't want people to come in?' Gon's worry increased. What if he was sick and needed medical attention?
He returned to the two other Hunters, who released themselves from each other's arms quickly as Gon ran in.
"I'm really worried about Killua-kun. He isn't letting me into his room! The door is full of his Nen!"
Kurapika put a hand to his chin in thought. "Maybe he's hiding a secret in there?"
"But the only thing in his room is chocolate," Gon added.
"Maybe he doesn't want to share?" Leorio shrugged.
Gon's eyebrow twitched. They were not being especially helpful. He decided that he would deal with this on his own, for Killua was his best friend, and Gon didn't understand how Leorio-san and Kurapika could be of much help as the two were stark naked.
Not pausing to wonder what those two were doing, Gon returned to the room. Then it hit him. He could just plow through the wall instead! He used Hatsu, focused on his fist, and slammed it into the wall. It crumbled like bread.
With that task done, Gon brushed off his clothes and walked into the dark, unlit room. He could make out piless upon piles of chocolate wrappers strewn amongst some uneaten ones. What in the world... He knew Killua was obsessed with chocolate, but this was just too much.
He ventured farther, practically swimming in wrappers. That's when he heard a low hissssssssssssssss...
Gon quickly went into defensive mode. Then he saw him.
Or it.
Killua was crouched in a feral position, his eyes a blank blue with the pupils barely being a vertical slit, his hair bristling like a frightened cat, his claws extended to the fullest length. He looked more animal than human. He let out another hiss, letting his fangs poke out. Gon knew if he attacked, he would be seriously injured.
"Killua? Killua, it's me, Gon!" Gon was more scared of what happened to Killua than the danger he was in. What had caused his friend to act like this?
Killua relaxed at hearing Gon's name. To Gon's imemdiate surprise, Killua's hair moved to reveal two flattened-back cat ears, and they perked up, twitching.
A cat? Gon had seen weird things in his life, but he couldn't figure that his best friend in the whole world was.. a cat. Complete with the slowly flicking back and forth cat tail, which Gon didn't notice in the dark.
"Uhh..."
"Gon... Killua... mate..."
What.
"What? M-mate?" This was getting more and more bizzare by the second. Gon started to walk backwards, and slipped on the ubiquitous wrappers. Killua's eyes flashed and he licket his lips, and advanced towards Gon on all fours.
"Making... nest... all week... Gon came..." Killua's words were slurred with pleasure and his breathing became more ragged. Gon was way out of his league here. He had no understanding of what Killua was saying, or why the cboy-turned cat thing started to run his hands on Gon's thigh.
"Now... we mate..."
"Killua, what is 'mate'?"
Kurapika and Leorio had just finished their 'fight', and after basking in the afterglow, remembered Gon.
"I wonder if the two are quite alright," Kurapika mused.
"We can just check on them. To make sure they're safe, right?"
The two returned to the table, shellshocked. They slumped on the couch, without a word.
After an hour, Leorio spoke up. "Did you see-"
"Yeah."
"Let's not talk of this again, okay?"
"Yeah."
2 months later, kittens ambled about the apartment. They got evicted because pets are not allowed.