Instinct

Natsuki Bakugou was fourteen, and cold.

This was an annoyance to her; she often tried her hardest to stay warm, hide from the winter and the cold it brought, since to her cold was an equivalent to weak. People didn't sweat when they were cold, and she needed sweat to make explosions. No sweat, no explosions. Cold equalled no explosions, and no explosions thereby equalled unsafe. It was a simple state of affairs, and one she had lived with for most of her life.

She was curled up in a thick winter coat, mittens and boots, while her best friend (and to some extent, only real friend) Izuku Midoriya sat beside her, wearing a hoodie, jeans and sneakers. Izuku Midoriya didn't really care one way or the other about the cold; it was just another state of being to him, the same as being hot, or wet, or dry. These things didn't phase Izuku, not as they would others. However, Izuku Midoriya was not cold. He was in fact quite warm, and his hoodie and jeans had little to do with it.

Izuku Midoriya had a Quirk. It was a curious Quirk in that defied the usual rules for Quirks as a whole; it was a mutation with a subconscious trigger, thereby defying the standard rule for mutations Quirks as 'always active' since Izuku's was only 'usually active'. Such as right now, as his Quirk, named 'It Will Not Die' after a scientist's murmured remark on one of his extracted blood cells and its befittingly undying nature, was doing what it did best; changing something about Izuku for the better.

In this case, his forcibly hyper-evolved cells were running hotter than usual, turning Izuku Midoriya into a portable furnace in the shape of a young man with almost rubbery black skin, luminescent green eyes and a mess of dark green hair. He was sitting quietly at the bus stop, rocking back and forth slowly and staring up at the ceiling with a smile on his face. He was counting the number of falling snowflakes he could see, one by one.

Natsuki was hugging herself and shivering, a far less enjoyable pastime, but she couldn't complain. She was never a winter-type person. Her Quirk made her more resistant to heat, but this itself meant she was more vulnerable to the cold. It was not a fun state of affairs, especially as this was one of the coldest winters on local records so far, and it only showed signs of getting colder. She longed for the warmth of her room, where two space heaters and the house furnace all ran at full power to turn her personal domain into a toasty warm little oven where snow was naught but a distant nightmare.

She made a growling sound under her breath, and she could practically feel Izuku stiffen up beside her, head jerking downwards so he could face her and then scan their surroundings. Izuku was jumpy to the extreme, perhaps a little too much so, but it meant that there were few things that ever took the two off-guard. Little did he know that in this case, Natsuki was not warning him of incoming danger but instead her own silent suffering in the weather.

"Something wrong, Naachan?" Izuku asked. "Izuku cannot smell any danger."

"It's nothing, Izuku, forget about it." Natsuki sniffled, rubbing her face with one hand before shoving it back into her armpit, where it was at least kind-of warm. "Just the weather."

"The snow is very pretty." Izuku nodded as if in agreement, looking up at the sky again. "Izuku has counted one-thousand-four-hundred and eighty-seven… eighty-eight snowflakes. Eighty nine…"

He stopped counting aloud, before looking back at Natsuki. His eyes narrowed a moment, as if scanning her, before he shook his head slowly.

"Naachan doesn't look like she enjoys the snow." he said, frowning. "Does Naachan think snow is bad?"

"No, just cold." Natsuki said, rubbing her thighs together to build up some friction and heat. "Ugh… freaking winter. Being all cold and shi- stuff…"

"Mmmhm." Izuku hummed his assent before looking back at the sky. "Naachan does not like the cold?"

"Nope." she said, looking at him this time. "Cold means snow."

"And Naachan does not like the snow?" Izuku once again asked, looking at Natsuki."

"He-Heck no!" Natsuki shouted, pointing at the sky. "It's cold and wet and sticks to everything and piles up like puddles but worse since it gets in your boots and is all cold and nasty, and it goes down your shirt and in your ears and UGH."

She spat onto the road, where a snowbank was slowly building up beside the curb. There was little wind today, only the snow, so the snow was free to pile thick and heavy all over the streets, sidewalks and rooftops. Natsuki took a longing look up and down the street, frowning. Her hopes were crushed by the lack of a school bus on either side. Izuku was staring at the sky again, a quizzical look on his face.

"Cold and wet?" Izuku asked. "But… cold and wet feels nice!"

Natsuki made a retching sound, before looking back at him. His opinions confused her, until she remembered his inability to actually feel the cold thanks to his cells… that probably made it a rather novel sensation, even refreshing perhaps. But that didn't make her feel any warmer, herself.

"But Naachan feels cold different from Izuku…" Izuku said, continuing down his train of thought. "So Naachan does not like the cold, since it is not nice for Naachan. Which means Naachan wants to feel warm…"

Suddenly and without any prior warning, Izuku reached over with both arms and wrapped them around her chest and shoulders, hugging her tight to his chest. He hummed, a deep rumbling in his chest that Natsuki could feel in her own chest, and she blinked rapidly in surprise. Izuku was fully capable of hugging but this was a little… odd. Especially given his usual nervousness about physical nearness.

Things only got weirder when he picked her up, and placed her on his lap. Izuku was a large boy for his age, not exactly a giant but quite sizable as far as fourteen year old boys went. But he had never seemed it until Natsuki felt him pressing all around her, his arms around her torso and her butt planted on his lap. She was suddenly engulfed by warmth, from every angle, radiating from his body.

Human-shaped furnace indeed.

"Izuku?" she asked, forcing herself to not stammer. "What are you doing?"

"Making Naachan warm." Izuku replied, before placing his chin atop her shoulder and nuzzling into her neck, spreading warmth there, before switching to the other shoulder and doing the same thing. "Naachan doesn't like the cold because it feels bad, since she cannot sweat when it is cold and Naachan need sweat to make explosions. So Izuku will make Naachan able to sweat and then she can feel good again. Izuku likes making Naachan feel good."

Natsuki blushed in spite of herself, trying to convince herself in her head that it was just a side effect of the sudden heat. But then Izuku purred like a freaking cat and she shivered down to the bones. Izuku seemed to read this reaction as a sign of her temperature dropping, and gripped her a little tighter. She couldn't bring herself to protest; this was much better than freezing her butt off on the bench, and even if it was a little humiliating she could handle it in exchange for this wonderful warmth.

The two sat there for a good hour, until Natsuki realized that her phone had been going off for over half that, blowing up with texts from her mother informing her that school had been cancelled for the day due to the buses being unable to run in the snow.

And even as she walked home leaning into Izuku, his powerful arm around her shoulder still at her request, she noted that she regretted nothing.

[X][X][X][X][X]

Tetsutetsu Tetsutetsu (son of Tetsutoro Tetsutetsu) was having what many would consider a fine day. He was on the fourth kilometer of his afternoon jog, after all, despite the falling snow and sub-zero temperatures. Heroes, he knew, operated in all conditions, rain or shine, snow or… not snow. Tetsutetsu couldn't really think of an opposite there, having already used shine. But despite his lacking vocabulary he knew for a fact that if he were to be a hero, the Fullmetal Hero Real Steel, he would have to be ready to fight for justice in any weather.

So onward and forward he trudged, through snow that grew knee-deep at points. He marvelled at how quickly it had consumed the city; there were few cars on the streets, and no buses were running as snowplows ran valiant missions to keep the most major streets at least somewhat clear. Tetsutetsu was okay with the solitude; he was used to working out alone.

He came to a sharp corner and rounded it at full speed, unprepared for what was awaiting him on the other end. He came into contact with something about as big as his generally imposing, muscular frame, bouncing back slightly. The thing he hit did the same, and Tetsutetsu raised a fist and readied a shout before freezing when he saw rubbery black skin, luminescent green eyes and forest green hair. It was a boy, perhaps about Tetsutetsu's age, with his arm wrapped around a very, very well-bundled... girl? Under the massive parka and multiple layers of pants Tetsutetsu could hardly tell.

"Watch where you're going, asshole!" the girl (the voice was a dead giveaway) shouted, her voice muffled by the scarf covering her entire lower face.

"It is okay, Naachan, Izuku is fine." the green-haired boy smiled, looking at Tetsutetsu. "Is he okay as well?"

Tetsutetsu blinked once, then twice, before looking around. He was fine, but… who was the kid talking about. Was there someone behind him? Had he hit someone while falling? He couldn't see anyone… and who was Izuku?

"Is he okay?" he heard the voice repeat, before very warm hand touched his shoulder and he turned to see the green-haired boy, concern drawn all over his face. "Did Izuku hurt him by accident? Izuku is very sorry…"

The boy bowed his head in apology, and Tetsutetsu blinked twice again before it clicked. The kid was Izuku, he was just talking about… himself. In the third person. Like a narrator or something, but… not. That must have meant that 'he' was…

"Oh, no, I'm fine!" Tetsutetsu gave the kid a thumbs-up, grinning. "Takes more than a random collision to knock me down!"

"Ah." Izuku smiled. "He does look very strong… does he work out often? Is he on a run? In the snow? He must be very dedicated to getting in shape, but he does not look like he is trying to lose weight. So he must be working to get stronger… perhaps he wants to be a hero like Izuku and Naachan?"

Tetsutetsu's eyelids were getting tired of all the blinking, but he blinked twice more anyways. That had been one heck of a run-on statement, and the fact that the kid was completely right was a little… off-putting. But also sort of cool. Maybe he was some kind of super-genius, and smarts were his Quirk? As much as Tetsutetsu liked his own Quirk, he couldn't deny that being insanely smart was probably more useful in the long run than what he could do.

"Ummm… yeah, that's… that's about it." he nodded slowly, before getting back into himself and grinning again. "The name's Tetsutetsu Tetsutetsu, and I'm gonna be a hero!"

He shot the two another thumbs-up, before noticing that the girl in the massive jacket was rolling her eyes while the boy just smiled.

"Great, even his name sounds like an extra's name…" the girl muttered, staring at Tetsutetsu. "What kind of name is that? Do you have a stutter or something?"

Tetsutetsu felt his blood go from cold to boiling in but a moment. He was okay with being made fun of for a lot of things. His massive beige eyelashes. His messy grey hair. Even his lack of overwhelming intelligence. But nobody, not even a girl, was allowed to make fun of the honorable Tetsutetsu family name. Nobody!

"You'd better watch your mouth!" he declared, raising his voice and pointing a finger at the girl. "I won't hesitate to hit a girl, not if she makes fun of my name!"

"It's the same name four times." the girl replied. "Come on, get some originality."

Tetsutetsu glowered, and without thinking he swung a fist. He was wearing some thick gloves due to the weather, so the impact would likely be muted a little, but this was still a powerful blow. Then… something happened.

The green-haired boy intercepted his punch with his own chest, which was akin to punching a cliff, or perhaps a particularly sturdy brick wall. Tetsutetsu's eyes went wide when his fist bounced off the boy's chest, before suddenly a powerful blow slammed into his own chest and sent him flying.

He hit the snowbank and there was an explosion of powdery white that filled the air and made it impossible for him to see for a long moment. He clambered to his feet, having landed on his back, and saw the boy standing in front of the girl, dropped into a low crouch and breathing heavily. Muscles were visibly tensing and bulging under his clothes, and Tetsutetsu could tell by the size of his biceps that this kid could hit.

"No hurting Naachan…" the boy snarled, voice totally different. Before it was kindly, gentle, the sort of voice one would expect a jovial younger brother to possess. Now it was harsh, growling, an enraged animal, an attack dog ready to go on the offensive.

Tetsutetsu triggered his Quirk, and his skin turned to steel. It was a useful Quirk, but this kid looked mad with a capital 'M' and ready to tear him apart. He felt something like fear seeping into his bones; this was like standing opposite a wild animal. He didn't know what was going to happen next, all he knew was that he was likely going to get hurt.

Tetsutetsu thrilled at the sensation. This was what he thought a fight should be! Two men ready to throw down, fist to fist and foot to foot, beating the hell out of each other for honour and glory, taking and receiving in equal measure. He dropped his own stance and raised his glittering metal fists, still wrapped up in his gloves. He grinned a savage grin and beckoned the boy, Izuku, closer.

Then the girl smacked Izuku in the back of the head with an open hand and a hearty 'thud', and the boy dropped down to all fours and whined. Like a dog.

Tetsutetsu blinked again.

"Izuku, no killing extras because they're mad at me." she said, looking down at Izuku, who looked painfully ashamed and guilty. "We've been over this. Would All Might attack idiots for trying to fight his friends?"

"No…" Izuku replied, staring at the snowy sidewalk. Tetsutetsu blinked again.

Who on earth were these two?