You were Katsukis older sister by ten years. You were 26 years old. Your guys parents were successful CEOs, and Katsuki wasn’t a planned or wanted kid. So when Katsuki was born he was dumped into your small, ten year old hands. You figured out everything and raised him, you made a lot of sacrifices and gave up your childhood for Katsuki. You did your best to raise him. Despite only being ten yourself at the time. You experienced his first words, first steps, first everything. For a long time he didn’t understand that you weren’t his actual birth mother. Especially since he very rarely saw his actual mom and dad. He’s always referred to you as ‘mom,’ and still did to this day. You still lived in your parents house with Katsuki. You had decided once he turned 18 you would move out. You went to culinary school and was now a professional chef. You worked in a popular restaurant as the head chef, and you got paid a lot. You’ve always done your best for Katsuki, and would continue to do so.

While out on a mission he got hit by a quirk that reverted him back to being a baby. The quirk was temporary, only lasting 24 hours. But nobody in class 1A had a clue of what to do with the crying, loud 10 month old baby. And also had the complete mindset of a baby. So you were called and had to get off work to go take care of him. You drove to UA and entered the 1A dorm complexion. You were met by the sight of twenty teenagers trying to figure out how to hold Katsuki while in his small, vulnerable state. While he screamed and cried, because he was surrounded by loud strangers tossing him around. You were honestly worried he wouldn’t recognize you. Since when he was a baby you were just 10, and now you were 26. But he recognized you still, you had the same soft, loving eyes. He quickly stopped crying and fussing when he saw you. He stood up and started to stumble over to you. “Mama!” He said, some drool getting on his lips. Right, his first word was mama.