MHA Age Regression Oneshots 💛

Platonic SeroMina

A/N: Hello guys, gals, and non-binary pals ( and everything in between)! I just thought I would let you guys know that I'm finally writing on a laptop and not my phone! Which means the format of my stories will probably change varying on where I write them. Thanks, enjoy!

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" Thanks again for helping me out man, that is super manly of you." Kirishima said, rushing to gather his things. This was his first time leaving the house without Mina in months and he was a little flustered.

" Yeah, of course, dude! I'm happy to help out with the little nugget." Sero responded, ruffling Mina's hair. She giggled at the action and nuzzled her head in his hand. Sero is Mina's usual babysitter when Kirishima is away or unavailable and the little alien had no qualms about it. She loved her Roro.

Kirishima finished scrambling to collect his belongings and let out a huff. " Okay, I think that's all I need for today. Mina, baby, you be good for Uncle Roro, okay? I love you, kiddo. I'll see you in a few hours." The redhead placed a kiss on his little's forehead before he walked out.

" Love you too, dada!" She called after him. The door shut behind him and the two left inside looked at each other. It had been a while since Sero had babysat Mina and they were at a loss of what to do.

It took the babysitter a moment but he finally remembered a few things that needed to be done. " Ah, right. How old are you, kid?" He asked. Mina stared at him and thought for a bit before answering.

" Wouldn't you like to know, weather boy?" She said with a dead face. Just then, she bolted to the bedroom and slammed the door behind her, locking it. Sero groaned, he knew it was going to be a long few hours.

" Mina, come on out, kiddo. I don't want to have to call your daddy and get you in trouble." Not even a crack in the door. She knows how much of a pushover Sero can be when he babysits.

Meanwhile, on the other side of the door, Mina was having a lovely time playing with her Monster High dolls. She was very upset that her caregiver left her for the morning but she knew if she threw a tantrum while he was still home, she would be in much more trouble than she was in right now. If she played her cards right, she wouldn't get in trouble at all.

" Mina Ashido, I'm serious. Open this door right now or I will have daddy take away your dolls." Mina gasped and dropped her dolls. She didn't know what to do. If she listens, she won't get her dolls taken but she doesn't want to come out! But if she doesn't listen, she could risk getting her dolls taken and a sticker taken off of her good girl chart!

She thought for a couple of seconds before she replied with, " But I play alone!" She waited for a response for what felt like three days but was only about 30 seconds.

" Alright fine, but you have to unlock the door. Uncle Roro is not going to be responsible for any injuries today. We're having lunch in about 30 minutes so enjoy your solo playing time. I'll be back to get you in a bit." Sero said, defeated. He too knows he can be a pushover.

Just then, he hears the click of the lock and sees a tuft of pink hair emerge from the crack in the doorway. " Okie, I crack door. Tanks, Uncle Roro. Loves you!" She said, flashing him a sweet smile. The girl went back to play with her toys and Sero walked to the kitchen to prepare lunch. But not before saying " I love you too, kiddo!"

As promised, Mina was retrieved from the bedroom 30 minutes later and was served her lunch. Peanut butter and jelly and fruit cut into cute shapes for her, and ramen for him. Granted, he gave her more time than he needed to prepare lunch but he knew how much her alone time meant to her and he wanted her to have at least some before her caregiver got home.

" Oh, you never told me how old you were, sugar." He said as he took a bite of his lunch. Mina took a second to think, eventually holding up three fingers. She wore a big smile on her peanut butter and jelly-covered face.

Sero couldn't help but laugh at the gesture. That girl was just so darn adorable. " Okay, cutie. Finish up, we have to squeeze in as much fun as we can while I'm here." With that, Mina scarfed the rest of her food down. As much as she loved her alone time, she absolutely adored playing with Sero. They don't get to do it often due to hero work so they try to savor their time together.

Fifteen minutes later, food was finished and faces were cleaned. The two had migrated to the living room where most of Mina's toys were thrown about. They started with playing superheroes. Sero would hide around the living space and call out for help. Mina would then respond with " I save you, Uncle Roro!" and rush to find him.

After a while, she got bored with heroes and moved on to building big cities with her legos. Which she would eventually break down and redo because it was never perfect enough for her liking. Sero simply sat on the couch and watched her for a bit. He did help her a little when she got so frustrated she nearly put a hole in the wall with a lego tower, though. The rage-filled pinky pie was too adorable to not snap a picture of.

Not long after the lego incident, she moved to play with her stuffies. She regressed much younger after that. So young, in fact, that she refused to be on the floor and demanded to be held. Well, as demanding as she could be with having the mental state of about a one-year-old.

She soon fell asleep in Sero's arms, comforted by his strong hold. They stayed like this for another hour before Kirishima came busting through the front door. " Dude! She's asleep!" Sero whisper-yelled to the redhead.

Kirishima could only respond with a quiet "Oops, sorry." He walked over to the couch and sat down next to Sero. " How long has she been out?" He whispered.

Sero grabbed his phone and checked the time. " About an hour and a half. She got really little before she fell asleep, wouldn't let me put her down." He responded.

Just then, the little stirred in her sleep, opening her eyes just enough to see that her daddy had arrived home. As soon as she caught a glimpse of the red hair, she quickly sat up and launched herself at him.

" Daddy home!" She shouted, clearly very excited to see her caregiver had arrived home safely. Kirishima could only chuckle and reply with " Yeah, baby, I'm home. Did you have fun with Uncle Roro?" He asked, pulling away just enough to look her in the eyes.

Mina nodded and hugged him again. Kirishima looked over at the babysitter with a ' was she good?' look on his face. Sero gave a breathy laugh and looked at Mina.

" Yeah, she was great." He winked at her, showing her he wouldn't tell her caregiver about the little incident from earlier. Mina giggled and reached for Sero to hold her.

" Okay, what are you two troublemakers not telling me?" Kirishima questioned, to which neither answered. They only looked at each other and laughed as the redhead sat with a confused look on his face. He would have to ask Sero about that later. But for now, he was just happy to be home with his little one. 💛