In this one reader and character are children

Izuku Midoriya

"That was so cool of you Ahi Chan!!"The greenette chirped as you both were walking to your apartment complex.He was referring to the fact how you used your quirk and jumped off a big rock without hurting yourself and won a bet with Katsuki.You culd practically see the admiration sparkling in his emerald eyes.

"Say,Izuku.Who is your best friend in the world?"you say,asking him.

"It's you of course!!You're my best-and my only friend ever!!"Izuku said as you come infront of your house and he gives you a tight hug.You rub his hair softly as you quickly pulled away and kissed him on the cheek.

"Chu~"

"Aaaaaaaaa-What was that for?!?"

"You didn't like it?"

"Yes...but lovers kiss...D-do you love me?"

"I love Izuku"

"Nani?!?...Ummm"

"Do you love me?"

"..mhmm..Will you kiss me everyday?"

"Sure!!I'd love to"

"YaY!"

Izuku's excitement made you blush as you bid him farewell and went inside.What you didn't know was that your father telling your mother

"I think it's time we teach her about boys"

Katsuki Bakugou

You picked up Katsuki as he fell from the bridge on the small river.He glared at Izuku,before grabbing your hand and getting up slowly as he shook with anger and humiliation. You patted his back as you took him through the forest towards his house.

"Y-you think I'm a loser...Don't you?" He said tears threatening to fall.It hurt you to see the boy who raged almighty in a state like this.Poor boy was just trying to impress you.You suddenly noticed he was limping. By looking down you saw he had a big gash on his knee cap.You quickly bend down and sat him on a nearby log,despite his protests,and took out your handkerchief and wrapped it on his knee as to stop the bleeding.He looked at you with his crimson eyes,and even as a child you found them very pretty.Suddenly he cupped your small face with his tiny hands and placed a quick peck on your fluffy lips and turned away,face burning red.You just replayed the scene in your head as you chuckled and kissed him on the cheek,and started to head home as he followed behind.

Shoto Todoroki

He had just turned 4 and his dad was getting more and more impatient about his quirk manifesting.He'd beat the poor kid,and you couldn't do anything,except wait and console him.He was a very nice boy and you wanted the best for him,but seeing him like that always made your baby heart crumble.One night,you were at a sleepover at his house when his dad barged in,and mercilessly abused him for not manifesting a quirk,and the helpless boy only howled in pain.After Enji left,however,you pulled him closer and rubbed his back as to console and comfort him,you rubbed his head as he cried onto your shoulder,his face nuzzled.

"A-am I not getting a q-quirk Ahi?"

"Sssh I didn't get mine too..I'm sure you'll have a cool quirk Sho-Chan,and I promise I'll have a cool quirk too and we'll be heroes together!!"You say as you lean in and kissed his left cheek,but you kept your mouth there,not pulling away..Shoto started to lush as suddenly his  left side burst into flames without a  notice and burned your lip.You clasped your lip as yyour eyes went wide

"I'M SO SORRY AHI CHAN I DIDNT MEAN TO<ARE YOU OKAY?!?!"

"No its-Sho Chan YOU GOT YOUR QUIRK!!:

:I-T-thats what your worried about?"

You nodded vigorously,your childish excitement getting the better of you as he felt his right side chill up uncomfortably.Soon enough his left shoulder freezed up an icicle.

"Hey Ahi.Kiss me again?" he said as he pulled you closer on his right cheek,cooling it in an effort to soothe your burning lips.

Pika pika

Pikachuuuuuuuuuuuuuu