#knycrossover

"Good morning, (Y/n)." oyaji greeted. He turned off the stove and motioned to a plate at the table tucked in the corner. Kai lazily yawned from his seat. "Hi."

(Y/n) greeted everyone with a groggy wave and a noise in the back of her throat. It was too early to speak to anyone. She turned to lazily grab a bowl of rice. When she made her way to the stove, the Old Man helped place a fried egg over her rice with a spoon of soy sauce and a sprinkle of sesame seeds. 

(Y/n) slid into the seat beside Kai and their oyaji sat across from them. "I have some business to take care of this week." he announced. "I'll be back by Saturday evening, so until then, you both take care of each other." (Y/n) mustered a nod as Kai muttered a brief 'okay'. The Old Man occasionally had business across the other side of Japan. Whatever it was that was so important, (Y/n) would never know.

As long as the Old Man didn't run into trouble, she was fine with seeing him leave. It would only be a little while. Then, she could see him all she wanted when he came home. "Kai," Oyaji said, "watch your sister while I'm gone. Take care of her, you're fifteen now. And cook in the morning too, don't wake up just to read a book." Kai nodded in understanding. When the Oyaji spoke, his word was law, and for good reason too.

"I understand." Kai said. "What exactly are you going to be doing?" Oyaji waved him off. "I'll tell you when I come back." (Y/n) spooned a bit of rice into her mouth. When she finished her food, she went to wash the dishes. Cool water splashed between her fingers as Kai and Oyaji discussed business--business (Y/n) wasn't needed in. Her hands were not clean, but her mind, etched with information and pictures of world, spoke of years she didn't need to live so early. 

"It's almost six thirty," (Y/n) noted. "We should leave." Oyaji ruffled (Y/n)'s dark locks affectionately. "I will see you both Saturday." He did the same to Kai. "Take care of each other."

The ride to school was uneventful. In the warm car sheltering the siblings from the winter chill, they were nice and toasty and unfortunately sleepy. Hari sat beside Kai, half asleep. He snored lightly.

"You're so grumpy today." (Y/n) remarked, kicking Kai's leg. She watched the scenery flash by as he yawned. "I want to sleep, why else would I be grumpy? It's Monday, who in the world likes Monday?" (Y/n) snorted. "Me too, but if I don't talk enough, then I'll fall asleep."

"Here," Kai handed her his water bottle. Even with the heat blasted on high, it remained half frozen solid (that's what Kai got for leaving it in the car overnight). "Cold water keeps me awake." (Y/n) took the bottle and pressed her cheek to its surface. "This is nice, but it makes me so relaxed I think I'll sleep anyway." A huff left Kai's lips. "That's as far as I can help, Imouto. That's a 'you' issue now."

Hari yawned wide. "I'll gladly take it if you don't want it, (Y/n)." She handed it to him, chuckling lightly. "Not sure it's gonna help."

The car came to a stop. (Y/n) got out with a wave to the two boys. Kai and Hari were a juniour high students, so they went to a different school not too far from here. They waved back. As (Y/n) turned towards the gates, the swerve of a car hit her ears. Everything happened so suddenly. The car barreled out of control, veering frantically to the side and straight towards (Y/n). 

Cold. That was the first feeling that erupted in (Y/n)'s bones. Misty white clouds left her lips as she stared up into the gray skies of winter. Passersby stopped to crowd the scene, some honking their cars while others watched in a stunned sense of fear. A strong pair of arms held fast and tight to her body. Something...something inside her shifted, and then her numb limbs began to explode in pain. Spots danced in (Y/n)'s vision as she turned to look up. 

"Don't close your eyes." Kai commanded, cheeks red from the cold. "Hari called 119 already, they're coming soon, okay?" (Y/n) weakly leaned towards Kai's warm chest. She didn't want to hear his loud voice, it was scary when he got angry.

"Stay awake!" Panic bubbled in Kai's throat. For some reason, (Y/n) wasn't getting better. She looked paler than before, the colour drained from her cheeks. Was there anything more he could do with his Quirk? Reassembling (Y/n)'s broken bones, vessels, and flesh wasn't enough. But why? Why when his Quirk always worked before?

There must be something else Kai couldn't see. A broken part, or perhaps internal bleeding? He placed a hand over (Y/n)'s stomach and activated his Quirk. She violently coughed, a sea of blood dripping down her chin. No, no, what happened?

Hari knelt beside Kai, eyes wide. "Why is your Quirk not working?" Kai could only shake his head. He didn't know what to do and that scared him. If he didn't know what to do, then how was he to help? Kai took a look at the red coating his bare hands and then the gloss like ice over (Y/n)'s eyes.

She would die from blood loss long before the ambulance showed up. If he didn't do something, anything, then the blood would forever stain his hands. Kai brushed dark strands of hair away from (Y/n)'s freezing face. This was filthy, dirty work, but for his sister? Oh, Kai would do anything.

"Don't--don't close your eyes." He cursed the faint crack in his voice. "You have to stay awake." He placed his index and middle finger to (Y/n)'s cold wrist, where a faint pulse drummed against his warm hand. He pulled out a handkerchief and blotted at the blood tainting (Y/n)'s delicate face.

"It's going to be okay," Kai heaved out a shaky breath, "your Nii-chan won't leave you."

An onlooking mother covered her mouth and burst into tears, terrified sobs so distant to Kai's ears. "(Y/n)," his golden eyes were the only source of light, "you have to stay with me, too. Fight!"

Chisaki (Y/n)'s eyes fluttered open and closed. The nagging want to sleep and wait this whole thing tempting. Haunting. It would make things easier, but Kai was begging her. She had to stay awake, for him, for Hari, and for herself. If she fell asleep, there would be no telling whether she'd wake up again. But oh, did everything burn and flare up in pain. It was as if someone had frozen every limb to her last finger, where the merciless chill of frost bit away at her body.

(Y/n)'s breaths were shallow. Pain filled her system and dots danced in her eyes with each deep breath. "That's it," Kai said, voice wavering like the wind. Tears threatened to blind his vision the longer he watched.

I will see you both Saturday. Take care of each other.

If (Y/n) died, would it be his fault? He could already see Oyaji's face filled with rage, filled with anguish, all because he couldn't protect his dear little sister. "I'm sorry," Kai whispered with a shake of his head. (Y/n) wasn't going to die, she couldn't because she was strong. So strong. Resilient. The best sister he could ever ask for.

Kai wasn't fifteen anymore, but that eleven year old stuck in the dirty streets of a bad city. (Y/n) was six, with only the clothes on her back and a (f/c) blanket she forced Kai to share with her. December had been unkind all those years ago, with icy snow and strong gusts of wind. There were no heroes to save them, but at least the rats had finally died from the cold.

"Nii-chan!" (Y/n)'s voice couldn't have been any sweeter. Despite the cold and lack of warmth provided by her thin clothes, she looked happy, maybe a little too happy. Kai raised a brow as (Y/n) skidded to a stop in the late December snow. "What happened to your face?" he grumbled, rubbing at her cheeks with his sleeve. "You're all dirty, again. Did you fall on your way here?" (Y/n) ignored his comment in favour of holding up a plastic bag. "Doesn't matter, look."

Kai jabbed a finger at the Kanji printed over the bag. "I can't read that, what is it? You didn't steal it, right?" The grin on (Y/n)'s lips only widened. "I'm not a petty thief. I was passing by that chicken place near main street when Haku-san gave me this. He hopes we're okay." A scoff left Kai's lips. A random person showing a simple act of generosity? "I don't buy it. Why would someone willingly give you food if not to poison you? There's nothing in it for the other party."

"Maybe this will change your mind." (Y/n) opened the bag and pulled out a paper carton. A savoury scent of honey and garlic hit his nose as (Y/n) handed him a plastic fork. "It's fried chicken!" she excitedly exclaimed. "There's rice too in here, isn't that great?" A frown pulled at the edges of Kai's lips. He still couldn't believe their luck. It had been half a week since either of them had a proper meal, only ever feeding on the scraps gathered after the bakeries and cafes closed (they threw out food they couldn't sell throughout the day).

"Not poisoned?" Kai inquired, poking at the fried chicken cautiously. (Y/n) rolled her eyes, that grin sliding off her lips in favour of a frown to match his own. "Either way, it's eat or die. Itadakimasu." She stuffed some food into her mouth.

"Hey--"

"It's good. Your choice, Nii-chan, starve or enjoy this wonderful chicken with me." The crunch of the chicken couldn't have been anymore satisfying than its taste. Along with the hot side of rice, (Y/n) was content. She shoved the carton towards Kai. "Just be thankful that Haku-san gave us food." she said. "Now eat, or else it'll get cold."

And that was how the Chisaki siblings found themselves sat on a park bench in nothing more than their summer clothes and a single, tattered blanket. "You know," (Y/n) said, "I'm glad you're my brother." Kai knitted his brows together, gaze falling to a tree on his left. "Oh really?" His cheeks grew warm, it was the first time someone had complimented him in a while. "Why are you glad I'm your brother?"

"Because I know you'll never leave me." Kai blinked before bonking (Y/n) on the head. "What are you talking about? Why would I leave you?" She let out a long, annoying whine. "That was a compliment, you dodo bird!"

"Who are you calling a dodo bird?"

"You!" (Y/n) stuck her tongue out at him. "Meanie!" An irritated chuckle left Kai's lips. He raised his hands and poked at her sides with an evil grin. "For that, you'll have to face my mighty wrath!" He took the carton of chicken, set it on the bench, and tickled (Y/n) mercilessly. Her giggles echoed in the quiet of winter, serene and joyful to the chilly nip of its cold.

"Stop it!" she laughed. "I'm--I'm sorry!"

"Never!" Kai exclaimed. "You're say the dumbest things sometimes, I swear!"

The food kept their bellies warm and hearts full with the hope that maybe, just maybe, things would get better. As (Y/n) smiled under the flurries of snow, Kai couldn't have been more content. Life was hard, but as long as they had each other, they would pull through. He knew it deep in his bones.

The memories came flooding back to Kai in a whirl of tears. That December day was just like today. The same snow, the same sky, the same two people on the same Earth. Why were they able to live through that, only to be torn apart by this?

Kai wouldn't stand for such sacrilege. He placed a hand to (Y/n)'s cheeks as a snowflake landed on her red nose. "Don't close your eyes!" He was losing her. "(Y/n), please!"

Life was hard, but as long as they had each other, as long as they were together, it would be okay. It had to be. It had to. "(Y/n)..." Tears trailed down Kai's cheeks and froze against (Y/n)'s ashen face. Was her pulse getting weaker? Why did her eyes keep closing? "Get up, you're fine, you can move. What will Oyaji say when I have to tell him this? He'll be...do you know how he'll react...?"

How could Kai ever go back to normal if not without his dear, younger sister? "And Hari! Hari's waiting for the ambulance right now! (Y/n), you have to stay awake!" Her eyes had already shut, those liquid golden hues hidden under snow covered lashes. "Come on, you can't leave me...!"

A woman reached out to place a hand on Kai's shoulder. He slapped her away. "Don't touch me!" She only frowned sadly. "Young man, your sister--"

Kai ignored her. He turned back to (Y/n), only to pause in horror. (Y/n) was gone--literally. Her body had disappeared from his arms, and if not for the crimson stains across the road, Kai would have thought no one had been there in the first place.

A teenager bundled tightly in scarves dramatically pointed to the spot (Y/n) had been seconds ago. "Did you guys see her disappear, too?!" A mumble of 'yes' and a few swears rippled through the crowd. Their voices were far away, a mere echo of the source of attention. Kai stared at spot (Y/n) had laid in moments ago as snow blanketed it softly. A gust of wind kissed the sides of his face, as if to apologise for what could not be undone.

"You know," (Y/n) had said, "I'm glad you're my brother." Kai didn't think much of her words at the time. There were more important things on his mind, like surviving another frosty night, or fending off criminals who would dare mess with them. Looking back on it, Kai wished he had said something different.

"Oh really?"

What a stupid response.

"Why are you glad I'm your brother?"

(Y/n) had smiled after. Kai thought it was out of happiness or content, yet in those liquid golden eyes, he finally understood. It was not joy, or satisfaction, but fear. Of dying alone in the cold, of losing the only person she cared for. "Because," --(Y/n) forced the brightest smile she could muster-- "I know you'll never leave me."

Ironic. Kai could stay by his sister's side as promised, yet she couldn't do the same. But this was his fault, wasn't it? If only he had done what Oyaji had asked ('Take care of each other'), then none of this would have happened. If only Kai had been quicker. If only Kai had known what to do. If only he had a gosh dang plan. Tears rolled down his cherry-tinted cheeks.

"You can't leave." His hoarse voice was lost to the wind. "(Y/n), you can't leave me."