A/N: Did I do this AU right? Honestly, I kind of rushed this, so the writing might feel weaker compared to the last fic I wrote. But this was something I've been tossing around in my head for awhile and wanted to try it out with these two, so hope you guys enjoy~

The cold. It was an all too familiar feeling Mei knew well.

She had just finished class and began getting her things ready before heading home. The weather forecast had predicted an unusual drop in temperature for the next few days and her mother reminded her to dress accordingly so she wouldn't catch a cold.

A simple leather jacket and a thin scarf were the only things the raven-haired girl needed to prepare herself. Any other person would've brought at least three more layers of wool as a barrier against the biting chill. But for Mei, she always had an unusually high tolerance to seemingly-freezing temperatures. At least, that's what she thought…

Before she even stepped out into the open air, a gush of wind nearly froze her skin solid.

"Snow? Well...that's to be expected," Mei remarked to herself as she noticed the falling snowflakes. There wasn't much else to do. In retrospect, it probably would've been a good idea to listen to her mother and pack an extra jacket just in case. Unfortunately for her, everyone else at school had already gone home and she wasn't going to call her mother to come pick her up. She'd rather risk getting a lecture.

In her mind, she told herself that she'd experienced much colder temperatures than this. It would feel humiliating to herself to say she's cold now.

Mei sighed to herself, knowing the possible consequences later, and began walking home. Not long after taking a few steps from the school she heard a voice call out to her.

"Mei!"

The raven-haired girl turned to find her blonde-haired step-sister running to catch up with her.

"What are you still doing here, Yuzu?" Mei asked, "I thought you went home with everyone else."

"I just needed to take care of some things with Harumin. I thought I'd end up walking home myself, but I'm glad I found you here. We can walk home together!" Yuzu radiated. She rarely ever got time to walk with Mei back home due to certain duties her sister had. On the other hand, Yuzu was sometimes held up at school, usually for causing unintentional trouble like accidentally blowing up the cafeteria, and Mei wasn't always willing to wait around for her.

Mei simply let out a hum of approval and gestured the blonde to continue walking, to which Yuzu happily followed.

Another cold gush rushed in enough for Mei to stop in her tracks. She summoned all her willpower to keep herself from hugging herself. Of all the days she has to go home late, why did it have to be today?

Before she continued walking, she felt Yuzu pull back her shoulder and offer her jacket.

"Here. You'll need this more than me," the blonde offered as she held it up.

Mei just looked at her dumbfounded. Was Yuzu crazy for willingly wearing nothing but her school uniform?

"No, I shouldn't-"

"C'mon, Mei. And don't think I didn't see you faintly shivering right when you were walking out," the blonde interrupted while holding up her jacket closer to her sister.

"Besides, I can always generate my own heat," Yuzu added.

Despite what the blonde said, Mei knew all too well that Yuzu still had difficulties in controlling her quirk. And even if she did have better control, she didn't want to give Yuzu the impression that she could rely on her heat radiating quirk 24/7.

"I've experienced colder temperatures than this. I'll be fine. You should put your jacket back on, Yuzu. You'll freeze to death," Mei pointed out.

Instead of obeying her suggestion, Yuzu playfully rolled her eyes, "That doesn't matter. And just because you're used to all the ice you make doesn't make you immune a blizzard. That's like if I were stranded in the middle of a desert."

Mei didn't say anything back and Yuzu simply looked at her with concern. If only the older girl didn't run into her at school. The younger girl hated making the blonde worry.

"I said I'm…" but before Mei could finish, Yuzu's eyes began to twinkle as she put her jacket back on.

"How about this?" she reached out her hand for Mei, only for the raven-haired girl to raise a brow.

"How is holding hands going to help?"

"There's something new I've been trying out…and I think I've got it down" the blonde tried to keep herself from stumbling upon her words. One part of her head was probably mentally scolding herself for such a cheesy way of getting Mei to hold hands with her, while another part was applauding her for a possibly smooth move. But either way, the girl wasn't lying about trying something new regarding her quirk.

"Just trust me," Yuzu reassured as she briefly averted her eyes from staring.

The younger girl mentally sighed to herself as she stared at Yuzu's offering hand. As much as she didn't want to admit it, even her high cold tolerance she had built up over most of her life learning how to use her ice quirk couldn't protect her from this weather.

It probably wouldn't hurt to accept other people's warmth every once in awhile, especially if it was Yuzu's.

Without saying anything, Mei took the blonde's hand, much to the latter's surprise.

On the other hand, Yuzu's face became red as a tomato from the sudden gesture. It was unexpected and overwhelming. She was expecting Mei to decline her offer again and instead just go back to persisting her about wearing her jacket. Warmth began emitting from her hand onto Mei's and normally, anyone else would've melted into contentment from basking in heat after a long day in the snow, but in this situation that wasn't the case.

"Ow!" Mei reflexively pulled her hand away from Yuzu's and began covering her palm with her ice.

"I'm so sorry!" Yuzu quickly apologized as she received a brief glare from the other girl. She made no further gesture for physical contact, but took a look at her sister's hand make sure she didn't cause any significant damage. She felt the sting of pain just from looking at Mei's expression, but luckily there were no visible burn marks she caused.

The blonde mentally scolded herself. After weeks of practice, she could've sworn she wouldn't mistakenly generate more heat than needed. She just didn't know that a burning heart would lead to a burning hand. Expecting the younger girl to give another sharp glare at her, she braced herself, shut her eyes, and quickly prepared for another apology as the raven-haired girl turned to face her.

"I see you still need more practice controlling that troublesome quirk of yours," Mei commented.

"Huh?" the blonde opened her eyes to look at her, dumbfounded. That was unexpected. She was technically being scolded by her younger sister, but there wasn't any trace of disdain in her tone. Mei, of all people, would have probably angrily reprimanded her for the injury she caused.

"Look, I'm sorry if I hurt you or anything. That...wasn't supposed to happen," she apologized again.

"Obviously…" Mei muttered to herself while still treating her hand.

"Are you okay?" Yuzu asked still looking over.

The pain seemed to have subsided shortly after and Mei dispelled the ice covering the palm of her hand.

"Yes. My hand should be fine now. As for you, I'm beginning to wonder what kind of practicing you've been going through," Mei noted.

"I swear I thought I had it! It really would've helped, but I guess…" Yuzu's voice grew softer with each word and looked down in defeat, "I guess everyone else was right."

Mei looked at the dejected girl with concern. It was true many people at the school often remarked about her lack of control and cracked jokes about how she'd always burn or blow things up. Sleeping on the same bed with the girl sometimes felt uncomfortable since her lack of control often led to the bed feeling like a sauna. It was the worst during the summer and Mei remembered how she froze her side of the bed solid just to feel slightly at ease. However, she admired the girl's efforts in maintaining control, despite how difficult it seemed.

Without a word, Mei reached out her other hand to Yuzu.

"What's this?" Yuzu asked in confusion.

"A hand. We're still walking home together, right?" she pointed out. Despite the injury, it was still minor, and how would Yuzu learn anything if she didn't at least try again?

"And...um…" Mei looked away to hide her embarrassment, "it is still pretty cold out. I thought it would be good for the both of us to stay as close as possible."

"Yeah, but…"

"You didn't burn this hand. Plus I'm giving you another chance to show me what new ability you say you're trying out," she continued still facing away from the blonde. Ironically, without the help of Yuzu's quirk there was enough heat radiating from how much her face was burning. "Hurry up before I change my mind."

Yuzu obeyed, but not before slightly hesitating. Mei was giving her another chance and the blonde was apprehensive she might burn her sister's other hand.

Taking a deep breath, Yuzu relaxed herself before reaching for Mei's hand. So far, despite feeling the same overwhelming build-up of energy when she first grabbed the younger girl's hand, she managed to keep everything under control. Unconsciously reaching out for more warmth, Mei slowly intertwined her fingers with Yuzu's.

Slowly, but surely, Mei felt herself warming up all over her body. She wasn't sure what possessed her to clasp the blonde's hand that way, but it didn't feel as if she was latched onto a stove like earlier. Her hand might not have been burning, but Mei surely was.

"I wonder if it's working," the older girl pondered, causing Mei to look over.

"What?"

"Do you feel warm, Mei?" Yuzu asked.

"I...uh…" Mei had forgotten for moment about her sister's radiating ability. Though, it was currently hard to tell whether or not she was warm from her own nervousness or from Yuzu's quirk.

"Yes, I am," the younger girl finally answered. Not a moment passed and the burning sensation settled into that of a calming fireplace that Mei's skin melted upon. Quirk or no quirk, she found herself the warmest when she was with Yuzu.

The younger girl's satisfying response was enough to plaster a grin on the elder girl and both motioned to start walking back home, hand in hand.

"By the way," Mei suddenly remembered, "what were you doing after school with Harumi? I thought you two finished cleaning whatever mess you may have caused last week?"

"Well, to be honest, she was helping me get the hang of the new radiating ability I'm trying out on you right now," Yuzu explained. Truth be told, it was the only ability she could actually practice getting the hang of around Harumin. The other girl's quirk wouldn't be of much help if it came to anything relating to combat, and plus, Yuzu never really asked Mei for help due to the possibility of disturbing the usually-busy girl.

"You actually seem to be more in control with your heat compared to before. Despite the...earlier burn, I'm impressed," Mei genuinely complimented, causing the blonde to blush.

"But," there was always a catch to every genuine approval Mei gave out, "you still have a long way to go. I can help you. That is, if you want."

Yuzu's eyes widened at the offer, "Wow, really! I mean, I don't want to get in the way of your busy schedule or anything." As much as she was excited at the thought of spending more time with Mei, helping her no less, she didn't want to cause any further trouble from the possible difficulties of managing her quirk. Harumin already barely escaped the possibility of turning into a puddle; she didn't want to think about how someone with an ice quirk would work with her's.

"I don't know what Harumi has been teaching you, but I doubt her quirk is suitable for you to pick up anything more than controlling your own temperature," Mei mentioned.

With that, Yuzu nervously took her offer with excitement. Mei set up a schedule where they would meet everyday after school, with the weekends being the most rigorous. Truth be told, Harumi did a decent job helping Yuzu out from further heating up any tables or chairs at school. Maybe there was something more in Mei's offer? She admitted to herself she rarely spent time with the blonde due to her busy schedule at school, and hoped this new thing they were both trying out would lessen the impression she was shutting her older sister out.

It would be difficult, yes; probably beyond comprehension just to simply teach Yuzu, someone with a completely opposite ability than her own, how to use her quirk. However, based from today, maybe the girl didn't always lose control of it like everyone says.

A/N: I'm cliche and of course I'd give Mei, an ice quirk and Yuzu, a heat-related quirk