"Big brother, wake up!" You say bouncing on the back of the boy who groaned.

"Big brother, wake up..! Big brother, wake up..!!!"

"Alright! Shut the fuck up and get out of my room!" Katsuki yelled angrily throwing you off him. Landing on your reptile feet you snickered and skipped to the side of the bed where he was facing.

"But big brother, you promised that we would go get some toys!" You whined.

"Well I changed my mind." He grumbled making you whine.

"Big brother you meany!" You cried hitting his head with your fist.

"If you want toys that much go buy them yourself! The money mom left us to buy it with is on the table!" He yelled before turning over with his back facing you.

With an annoyed huff you turned and walk out of his room shutting the door close.

"Finally.." Katsuki muttered tiredly.

It was quiet till he heard the front door open. 'She wouldn't actually go out alone right?'.

Katsuki thought to himself looking the door of his room in a sitting position.

He waited for some sound to show you were still in the house but heard nothing else but his breath.

"Fuck!" He cursed jumping off the bed.

' "Now Katsuki, if (Y/N) ends up going out alone you are in big trouble!~" Mitsuki say before she closed the door of his room.'

'There is NO way I am getting in deep shit today!'

[--]

"Big brother is so mean... I just wanna buy a new ball..." You mutter.

Dressed in a big T-shirt under a big neutral colored jacket with boy shorts and pump shoes. You wandered down the street to go to your favorite toy shop.

"And I am hungry too... Maybe I can buy some meat before I go 'savage'." You say to yourself entering the store.

"Morning kiddo!" One of store employees greeted you.

"Hello!" You greeted back before scurrying to the toy section looking for the ball section.

The store was a general store, selling snack and school supplies together with toys it would be obvious why it's always been tad bit crowded. 

Wandering around the store you came across a familiar figure.

"Oh its like that doll big brother has.." You say looking at the other merchandise the section held.

"Should I buy this?" You asked yourself that was until a foam bullet toy gun caught your interest. You almost felt your eyes sparkle in mischief at the sight of the gun.

"Ooh! I could use this, Hehehe!" You snickered to yourself.

Suddenly, out of the blue, the gun fired by itself and the bullet went flying to the head of another person.

"Ouch." The person lightly spoke scratching the back of their head.

"Ah, I am so sorry!" You say walking up to the person who held the bullet in his hand.

"Ah, its okay.." The person told you.

Looking at his face you suddenly gasped and pounced the poor individual. Making them fall down in shock.

With hands on the person's cheek you looked at their face in fascination.

"You..."

The person looked at you with a beyond surprised face. "I.. what..?"

"You have stars on your face!" You exclaimed touching the dots on his face making the person blush madly.

"E-Eh..!?"

Looking at the person, you were able to identify them as a boy, the same as your brother, with green hair and eyes, with freckles that you identified as stars.

"It looks so cute and cool at the same time! I never met someone with so many stars on their face!" You gasped.

The green haired blushed at, what you didn't realize, was a compliment.

"Oh... But your hair looks like a broccoli.. I feel like I am gonna throw up." You bluntly say shocking the boy who stiffened feeling his confidence leave him.

Finally realizing you are squishy the poor thing you hopped off. "Whoops, sorry, Mr. Big brother!" You say sheepishly.

"Oh no its okay..." The boy modestly ease.

"I was just so surprised by your face." You grin. "My name is (Y/N)! Nice to meet you!"

"Oh hello, (Y/N)-chan.. I am—"

"Hey, Kiddo! Your brother is looking for you outside! You are looking for a ball, right? Come on!" An employee shouted from the other end of the aisle cutting you introduction short.

"Oh right..! See next time, Mr. Big brother!" Without another word you grabbed the gun and bullet from the ground and washed down the aisle.

Before you turned the corner you waved a 'good bye' at the green haired boy leaving him alone in the aisle with the lack of words.

All he could do was gave a small wave back before you disappeared.

A sigh escaped his lips standing up with an amused glint in his eyes. 'Oh how that reminds me of a certain someone back when we were kids...'.

[--]

"Ouch ouch ouch ouch!!" You whimpered as Katsuki dragged you by the fin.

"Do you ever learn your lesson?" He grumbled carrying your bought items in one hand.

"What lesson!? I did what you said! Don't go putting the blame on me, stupid big brother!" You yelled making him growl.

"What ya say brat!?" Katsuki look back at you letting go of your ear.

With an angry pout you shouted at him. "I said you are a fart!"

"Why you..!!!"

With an angry fist raised Katsuki chased you around which ended up leading you both to a playground. "Get back here!"

"No Way!"

"I am gonna get you!

"Ha! I bet you can't!"

"You wanna go!?"

"Yeah!"

In the end your quarrels ended up as silly banter. It was amusing watching you both argue back and forth about measly things.

Soon the sun reached last noon and checking the time it was already 2 pm. "Oi brat you hungry?" Katsuki looked at you who was picking up rocks.

"Yeah.. I think already past the time." You said looking at each material. With a sigh Katsuki stood up from the bench he rested on and walked to you.

"Alright come on." You pouted not wanting to go yet. "But I don't want to go..." You yawned a bit making him smirk.

"Well if we don't go now, I may not be able to hold this good mood that will let me carry you." Hearing that you jumped up on your feet.

"Waah! Carry me!" You plead tugging on his pants.

"I don't know.... I think I am changing my mind.." Katsuki teased turning to walk away.

"No!" You cried clinging to his leg as he walked away.

Chuckling Katsuki picked you up and held you in a piggy back way. Cheering you wrapped your arms around his neck.

"Hey big brother..." You mumbled in his shoulder.

Grunting in acknowledgement you trace circles in his back. He looked back at you with confusion at your attitude.

With a shy look you muttered under your breath. "Love you...big brother"

The boy blinked in surprise at your sudden statement before smirking. "Well I share similar feelings for you too brat."

Hearing this you grew a tic mark. "Hey! I said the 'L' word! You say it too!"

"No way! It sounds gross when I say it for ya."

"Arrgh! Big brother is really mean!!"

"Ow—hey!!"

===============================
Hey guys! Hope you enjoyed this chapter, I am sure you know what is the next incident closing in.

Hopefully I can put the story and series together just fine. But because that reader is not always gonna be in the original plot so there would be lots of time skip unless I put surprises in.

I will be taking some scenarios from the [Author's Message #2] and making a few shorts.

But I will spoil you guys, that the reader would be more involved from the second season out.

Also I will be polishing up so don't mind the updates of the previous chapters.