Chapter Text
A girl not younger than 6 years old ran across the playground. Happily smiling and laughing as her brother chase her. The girl's black hair swish around in the wind as her dark blue eyes sparkled with excitement.
"I'll catch you, Crystal!" Her brother called out as he ran to catch her.
"No you can't, Kaa-chan!" She called out to him.
She ran and heard a booming sound from behind before someone tackled her to the ground.
"See!" Her brother announced and they both giggled.
"No fair, Kaa-chan! You can't use quirk playing chase the mouse!" The girl pouted her lips as she looks away from her brother.
"It's not my fault I knew it early, you idiot." Her brother ruffled her black hair.
"Kaa-chan! My hair is all messy." The girl pouted more as she tried to tame it down.
"Katsuki! Crystal! Time to go home!" A voice of a woman called out.
"Ok!" Both of them answered.
Bakugou Katsuki stood up, his sandy blond hair was messy because of the fall, his red eyes look down to his twin sister before he reached out a hand to help.
The girl, Bakugou Crystal, smiled and took the hand before her brother lofts her up. She dusts some dirt off from her short and shirt.
Katsuki offered her to take his hand as both siblings walk together to the woman who had the same hair and eye color as Katsuki, Bakugou Mitsuki, stood to wait for her two children.
"Look at both of you, so dirty. Let's get both of you to wash off." She said as she took each one of there hands.
"Mama! When will I have a quirk?" Crystal jumped up and down as she asked her mother.
"I don't know but maybe tomorrow something good will happen." She said to her daughter.
"I can't wait to find out, I want to train together with Kaa-chan soo. We will be the best heroes in Japan, right Kaa-chan!" She asked her brother.
"Of course! We are the Baku Twins for nothing." He raised his hand.
"Heroes like All Might!" Both of the children announced.
The three of them talked and walked back home. Mitsuki opened the door to see her husband, Bakugou Masaru setting down the plates on the table.
"Papa! We're home!" Crystal ran to her father and hug his knees.
"My what happened to you, Crystal. Katsuki please don't try to use your quirk on your sister." Masaru said to his son.
"But I didn't do anything dangerous." The young boy stated.
"He's right papa. We were playing chase the mouse." Crystal started to tell her father her story before Mitsuki took her in her arms.
"That can wait because you two need a bath." She took Katsuki hand as she walks to the bathroom. She filled the tub with warm water as she removes the dirty clothing and puts them in the basket.
She placed both Katsuki and Bakugou in the tub and both of them played in the water. The children played with their toys and splashed around.
Mitsuki dried them and puts them in their pajamas before going downstairs for dinner.
Dinner was fun and quiet with the exception of Crystal almost throwing her meat to Katsuki.
They watch some TV as Crystal and Katsuki did their studying. After that, they had been tucked into their beds as their parents turn off the lights.
Mitsuko and Masaru sat down on the couch in the living room.
"When will we tell her about this?" Masaru asked his wife.
"I don't know but they had begun to act like siblings now. The first time we saw her and took her in, she was so shy and afraid." Mitsuki said as she remembered that day.
"Yeah, Katsuki seems to love and protect her like his own sister. Maybe we should tell both of them when Crystal has her quirk." Masaru suggests.
"She must have inherited one of her parent's quirk as they are both powerful heroes," Mitsuki said.
"Sora and Kazu will be grateful that you were the one taking care of her. They died being a hero and they had trusted you with all their heart to take care of their daughter." Masaru placed his hand on his wife as she saw how her knuckles became white.
"But they are good people and friends, why did they have to die? They were the only one who believes in me and it's funny how they even I introduced me to you." Mitsuki remembered Sora's smiling face as she introduced Masaru to her.
"I know but know it's our job to give a happy family to Crystal. They are watching us from above and if they were still here, they would have thanked you." Masaru comfort Mitsuki.
"We will tell them after Crystal founds her quirk." They both agreed.
They didn't know that Crystal and Katsuki had woken up and came downstairs to hear their conversation.
Katsuki looks at his sister to see tears running down her chubby cheeks before she ran to their room. He catches up and opens the door to see Crystal crying on their bed. He walks over and up onto the bed.
"Are we really not siblings, Kaa-chan?" Crystal said through her sobbings.
"No! Why would you think that! I am your brother and you are my sister." Katsuki hugs Crystal.
"But Mama says that I have different parents." Crystal sobs into her brother's shirt.
"Even if we are not related by blood but we are still brother and sisters, we are still the Baku Twins and you are my little sister. I will protect you with everything I got because we are siblings." Katsuki said with tears in his eyes.
"Kaa-chan!" Crystal cried out as both siblings hug until they fallen asleep.