Disclaimer: I do not own My Hero Academia or any of its anything! It all belongs to Kōhei Horikoshi!

Prologue

BOOOM! CRACK!

As the roaring sounds of thunder and lightning echoed throughout nighttime Musutafu, a young girl trembled in fear underneath her All Might blanket as quiet whimpers escaped her one after the other. Her blanket shook along with her tiny balled-up form as she clenched onto the covers strongly.

"R-Rain, rain, g-go away.. C-C-"

BOOM!

"Ee!" When the storm exploded once more, she visibly flinched as her fearful quivering intensified, to the point where the wooden bunk bed she laid on, the girl occupying the bottom bunk, even started to shake a bit. The little one sniffled as she caught her breath a few seconds later and carried on with her rendition of the innocent nursery rhyme. "...C-Come back another d-day.. Rain, r-rain, go a-away..! Come back a-another day..!"

While she sung and sobbed to herself, a little boy's waking groan echoed throughout the bedroom, the sound emitting over the girl from the top bunk.

"Mmm.. What's.. What's going on..?" The little green-haired boy muttered to no one as he sat up tiredly on his bed, his own All Might blanket falling down to his lap and his hands lifted up to rub at his sleepy eyes. Unlike the girl, the storm didn't bother him at all.

When he had woken up enough to hear the girl's crying more clearly, six year old Izuku Midoriya, who wore a dark green pajama shirt and pants, blinked in a perplexed manner as he looked off to the edge of his bunk. Then worry showed itself on his face upon completely processing the familiar voice that sung in order to comfort its poor owner..

"Izumi?" He concerningly called out to the girl as he pulled his blanket off of him. Afterwards, he slowly crawled over to the short ladder by the foot of his bed and carefully descended along it, being very careful with each of his steps until he eventually felt his toes touch the cold floor at the bottom. The storm's lightning flashes would create some visibility for young Izuku at random intervals, helping him see where his feet were going here and there while he climbed down.

He received only trembling whimpers and sorrowful singing as a response to his call..

Izuku frowned as he walked over to the nightstand sitting by the bunk bed, turning on a lamp that stood atop of it.

With the room now properly lit, Izuku released a heavy sigh when he witnessed the shaking, blanket-clad figure of his twin sister more clearly.

Being the caring big brother that he was, and yes, he was born first, Izuku couldn't stand to see his twin in such a distressed state as he steadily approached the bottom bunk with the intention of comforting the terrified little girl. "Izumi? Are you okay?" He inquired concerningly as he gently placed a palm over his twin's nearest shoulder, who's name was Izumi, Izumi Midoriya.

Izumi twitched and fretfully squeaked when feeling her brother's touch, having been too petrified to hear him talking to her. When she reacted, Izuku acted quickly to calm her down.. hoping to do so somewhat as it wasn't going to be easy seeing as how thunderstorms were one of her worst fears.

"Ssh! D-Don't worry, Izumi..! It's just me.. Your brother.."

When she processed her twin brother's voice this time around, Izumi's body and anxiety immediately settled down a tad bit as she started to slowly pull down her blanket..

"I-Izuku..?" The girl greenette sniveled as she peeked her head out from her blanket, looking up to her worried twin who towered over her.

They were identical in almost every way possible, what was different about them was obviously their genders and their unkempt hair, as Izumi's hair was slightly longer than Izuku's own.

Feeling pure delight and relief as she felt like she had been saved from her torment, Izumi launched herself off of her bed after throwing her blanket off of her. "Izuku!" She cried as she didn't hesitate to jump at Izuku when she got onto her knees, pressing herself against him as she held onto his neck, burying and nuzzling her teary face deep into his chest. Izumi's own nightly attire was a long, dark green nightgown.

Izuku didn't even flinch as he saw the motion coming from a mile away, catching his little sister by her waist when she latched onto him. He didn't waste time as he swiftly got to embracing Izumi while he patted her lightly on the head, and then, in a soothing voice, he whispered to her..

"Ssh.. It's all right now, Izumi.. Don't cry anymore, okay..? I am here.. I'm sorry I took long.."

"Th-The thunder.. it's scary..!" Izumi squealed as she held onto Izuku for dear life, using his bodily warmth as a means of comfort and a sense of safety.

"It's not going to hurt you, Izumi.. It's just a stupid thunderstorm.. It can't do anything but make noises and light up, that's it.. Besides, I wouldn't let it hurt you even if it tried to.. So you have nothing to be scared of... All right? I got you.. always.." Izuku replied, sounding ever so patient and caring.

Even though she knew her brother was right, Izumi was still hopelessly afraid of storms. The intimidating intensity of their frequent eruptions and those damned blinding flashes.. It all just struck fear into her being so effortlessly. She truly couldn't help it. She was beyond glad and grateful that she had Izuku in her life. Because she wouldn't know what to do without him. Sure, they may have their loving parents around to take care of them at any given time. But to Izumi, life just wouldn't ever be as... relaxing as it is now if her dedicated twin wasn't around to be there for her, for he was her other half..

And she needed her other half, always and forever..

"Do you.. pr-promise..? Always?" Izumi gulped as she managed to recover enough to look up at her slightly taller sibling, giving him a pleading stare as she grasped onto his shirt tightly.

Izuku smiled as he nodded with conviction. "Mhm, always and forever." He vowed.

Okay, maybe it wouldn't be so tricky because just like that, Izumi's panic started to gradually settle as she took his words to heart. But she would still wince and bite her lip nervously whenever thunder bursted through the sky. Thankfully, Izuku's embrace prevented her from having another crying fit as she felt secure in his arms. Now that he thought about it, she was always an easy one for Izuku to please, so suppose it wasn't a surprise to him that she fought through her fear all thanks to some reassuring words that came from him. But not to say that they weren't sincere.

"Always.. and forever." Izumi weakly smiled as she sniffed once and leaned off of Izuku a little bit, wiping away her tears with one hand but her other stayed connected to his shirt. When she composed herself somewhat, she displayed a guilty frown as she casted her sights down to her fidgeting feet. "I'm sorry, Izuku.." She whimpered with a quivering pout.

"Hmm? What are you apologizing for?" Izuku responded, tilting his head slightly in bewilderment.

"I woke you up... when you were probably having a good sleep.. I-I'm so sorry..!" Before the girl's waterworks started up again, Izuku smiled warmly as he nonchalantly pulled her in for another soft hug, Izumi accepting it as she held him tightly once more, returning to her earlier position with soft, guilt-stricken sobs emitting from her. "I'm always causing you trouble..! I'm such a... a-a bad sister..! Please don't be m-mad at me, Izu..! Pl-Please..!" She cringed as she hoped that her big brother didn't despise her for resolving a predicament for her... again. All of the stuff that can be considered bothersome that she has him dealing with on a day to day basis for her sake was just now hitting her.

"Don't say that about yourself, silly..." Izuku sighed, stiffling a chuckle as he caressed the back of his distraught twin's head. "You were never a bad sister, Izumi. And I'm not mad at you at all. It's my job as your brother to help you whenever you're sad or upset, and it's a job that I love doing. So I don't mind helping you whenever you need me one bit. Just like the storms... I'll always, and forever, be there to save you from everything else. That I can promise too." He smirked as he turned his head and kissed Izumi right on the forehead, his hold on her getting firmer.

Because of the kiss, Izumi couldn't help but blush as she flusteredly nuzzled back into his chest, taking in his affection gladly. "You.. Y-You really mean all of that..?" She questioned bashfully for reassurance.

"Every word." Izuku softly answered as he rubbed at her back.

Izumi allowed a pleasant silence to go by before she spoke up again, sounding content and undeniably happy. "You're the best... big brother.." She smiled as she whispered that, all of her worries washing away instantly as she could hear that he truly meant what he said. "I love you.."

"I love you too. You'll always be the best little sister to this big brother.. Never forget that, Izumi."

"I won't. I promise." The little sister replied.

"Good.." Izuku grinned, planting another kiss on her head of hair this time around. "Let's try and get some sleep now, okay?"

"Will you... Will you sl-sleep with me..? I don't want to be alone.." Izumi cutely requested as she glanced at the window hesitantly. When lightning flashed, she immediately squeaked in surprise and hid her face in Izuku's shirt again.

Seeing no other choice, Izuku nodded as he comforted her again with head pats after her frantic reaction. "Sure, I can do that. Come on." He softly replied as he lead her towards her bunk.

"Th-Thank you, Izu.." Izumi whimpered before she crawled into bed quickly, flicking her blanket over her as she did. Izuku didn't fall far behind her as he turned off the lamp before he did the same as soon as she was comfortable.

When the twins were laid down next to each other, they turned over to lay on their sides, facing one another.

Izumi latched onto Izuku right away, hands clenched on his chest, face hidden in his neck and the front of their small frames connected.

"How are you feeling now, sis?" Asked Izuku as he leaned the lower half of his face into her hair.

"Better than I was before. You're... s-so warm.." Izumi shyly responded.

Izuku softly chuckled. "You are too, Izumi. Very warm. I like it."

Izumi blushed for the second time tonight as his words made her heart skip, a gleeful smile curving on her lips. "Th-Thanks.."

Before Izuku said anything else, he yawned heavily. "You're welcome.." He spoke tiredly. "Now let's get some sleep.. I'm still really... really tired.." He scoffed, getting himself ready for another relaxing slumber by cuddling up to his twin, one arm around her waist and his other using its hand to brush her head.

"Mmm.." She nodded, sleep sounding amazing right about now for her as well. "I'm sorry again.." She gave off a yawn as well before continuing with her apology. "for waking you up.." She exhaled, snuggling up to Izuku closely, taking in as much of his warmth as she can gain as she could hear his heart beating steadily, which helped ease her anxiety.

"Don't worry about it anymore, sis.. Water under the bridge.. Just sleep now.."

"Okay.. Goodnight, Izuku.. I love you.." The girl muttered as she immediately started to doze off at his call, the sounds of the storm being drowned out by Izuku's calming voice and breath.

"Goodnight, Izumi.. I love you... too, always and... *yawn* forever.. Sweet dreams.." And with those words, sleep swiftly took control of little Izuku's being once more as he started to lightly snore within seconds of shutting his eyes. The same thing happening to Izumi a few seconds later as a small smile would remain on her expression for the remainder of the night..

Always and forever.. Ever since that night and to this day, I think that is when I have always taken those words to heart.. And when I had truly fallen hopelessly in love..

..with my twin brother..

A/N: I regret nothing! XD

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Until next chapter, whenever the hell that'll be, deuces! XD