This is a mix of him thinking your cheating your first argument, you guys make up and your first I love you.

It has been 8 months of you and Mirio dating (This takes place when He and Midoriya see Overhaul for the first time)

I was with White Eye my older brother he took me in for my internship. I was happy I get to spend time with him. We are already really close but now I get to see him more.

White Eye: (Y/n)!

Y/n: Yes sir

White Eye: *Groan* I told you when we're alone to call me Jack! I'm your older brother COME ON!!

Y/n: *Giggles* I know but it's fun

White Eye: Okay Whatever lets go on patrol *Grins*

Y/n: Alright! *Smiles*

White Eye: I like your Hero Costume by the way

Y/n: Aw thanks *Smiles*

While walking I told him about U.A and how I started dating Mirio. He went full protective brother mode, he does know Mirio he has seen him play with me when we were kids but never talked to him.

White Eye: As...long as he's treats you right....I'm....Fine...with it

Y/n: you are really protective! *Giggles*

He went to hug me and started to ruffles my hair while laughing.

White Eye: I am your Brother after all!

Saying that Paparazzi came and start to take Pictures of us and started to ask us questions.

White Eye: Yes I am All Mights child too and She is my little sister.

After a while we heard screaming and we ran past but the Paparazzi. There was a man that was keeping a little boy hostage.

Boy: Please help me *Sobs*

It pained me to see him he was probably 6 years old the guy was huge.

White Eye: Get ready I'll distract the Villain you get the boy.

I nodded and with that he teleported in front of the guy and punched him square in the face. He dropped the boy and I quickly went to him. I grabbed him and started to take him to safety.

I saw my brother fly by me he crashed in to a wall my eyes Widen

Y/n: WHITE EYE!

I looked behind me and saw the Villain get bigger, he then started to go after me. I started to carry the boy again while dodging the Villains attack, I saw my brother behind me.

Mirio's POV

After we told Sir Nighteye about Overhaul i heard something scream. Me and Midoriya ran to see a huge Villain. I saw (Y/n) with a little boy in her arms the Villain was Chasing her. I ran to help her but the Villain his the ground hard and She ended up crashing to a building. She protected the little boy from harm but it looked like she was in pain.

Mirio: (H/n)! ( (H/n) means hero name)

I started to run to her but she stood up, she hide the boy and jumped and punched the Villain in the face. Then White Eye appeared and started to help her!

Midoriya: Thats Right she's taking her internship with White Eye!

They beat the Villain but after they did the Villain was able to Smacked both of them and they went flying to a building I rushed to her and White Eye.

White Eye quickly got Her and started to talk to her. He hugged her and she hugged him back it looked like a meaningful hug.

White Eye: I thought He killed you (Y/n)!!

Y/n: You worry to much Jack!

He hugged her again and kissed her forehead she just laughed. She isn't supposed to call pro hero bye there first name it's usually was she cheating on me? I started to get angry she then spotted me and smiled.

Y/n: HI LEMILLION!

I didn't answer her she looked confused and started to walk towards me but the little boy caught up to her.

Y/n POV

Why was he looking at me like that, he looked disappointed I started to go to him but I was stopped by the little boy we saved. Mirio left and Midoriya looked at him confused.

Boy: T-Thank you for Saving me! Y-Your my HERO!

That made me so happy, it almost made me tear up Jack looked at me and patted me head.

Y/n: I'm (H/n) what's your name?

Boy: I-I'm Adam

Y/n: It's nice to meet you Adam *Smiles*

He went to hug me and and I hugged him back he then looked at Jack and hugged him too.

I told Jack i wanted to catch up with my friends he just nodded with that I left. I search for Mirio and I saw him in a Ally.

Y/n: Hey Love what's wrong?

He didn't say anything I went to hug him but he gently pushed me away. I was confused he then turn around and I saw tears coming down his cheek this broke my heart.

Y/n: Mirio what happened?!?

Mirio: are you really asking me that!

My eyes got wide his voice was filled with anger it made me flinch.

Y/n: Yes....what's wrong?

Mirio: Not only you got hurt BUT YOU STARTED TO ACT ALL LOVEY DOVEY WITH WHITE EYE HES OLDER THAN YOU WHATS THAT ABOUT!

My eyes widen again he got jealous and now he thinks I'm cheating on him. Oh crap I never told him that he's my brother.

Y/n: Mirio listen it is-

Mirio: It isn't what I think, I SAW THE WAY YOU GUYS WHERE HUGGING AND YOU CALLED HIM BY HIS NAME!

Y/n: Mirio please l-listen to m-

He started to yell more and i started to tear up a bit I really hurt him and it hurts me that I'm the reason.

Y/n: Mirio let me explain

Mirio: You really hurt me (Y/n)

at this point he was crying even more I started to cry seeing him like this. I ran to him and hugged him tightly.

Y/n: MIRIO I WOULD NEVER DO THAT WHITE EYE IS MY OLDER BROTHER. HE WAS JUST BEING PROTECTIVE AND HE REALLY CARES ABOUT ME! I WOULD NEVER CHEAT ON YOU.....I LOVE YOU TO MUCH TO DO THAT!

I was still hugging on to him while crying, it was quite for a while and then he lifted me chin up. I looked at him with Tears in my eyes.

Mirio: Y-You love me

Y/n: Yes you idiot i love you, a lot! I'm always going to be yours!

Mirio: Say it again

I put in if my hands in his cheek and looked him in the eyes.

Y/n: I love you Mirio and I'm always going to be yours *Smiles*

I wrapped my arms around his neck and kissed him with lots of love. He wrapped his arms around my waist and pulled me closer to him. We separated because oxygen was needed.

Mirio: I love you too Sunshine and I'm always going to be yours too *Smiles*

Y/n: You dork *Giggles*

Mirio: I-I'm sorry I just got jealous and started to Over think.

I looked at him with a knowing smirk he knows I won't ever let him live it down.

Y/n: it's okay, I love you *Smiles*

Mirio: I love you too! *Grins*

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I know it was really bad many things wrong with this I apologize I didn't have any good ideas for this.