You were at Katsuki's house. Sitting on his couch, in your school uniform, holding a book in your right hand, reading it; while your left hand was in Katsuki's hair, playing with it gently, while his head was in your lap. He laid on his back, head in your lap, in his school uniform too, reading the same book.
You were reading it for homework. You hated reading for homework, but at least it was a little interesting. You two were reading in silence. So caught up in the moment that you didn't even realize, his mother, Mitsuki, who'd just come back from a lunch date with one of her friends, was standing in the doorway, watching you play with her sons hair, so tenderly. She'd never seen her son so comfortable and relaxed with anyone besides his closest friends before. And it seemed like you might be the closest.
Katsuki: "Ugh, this book is boring as hell. I'd rather eat my eyes out for breakfast. I'm gonna get some juice. You want some?"
You were so busy reading you still hasn't noticed Mitsuki in the doorway. Katsuki hadn't either, since he was already off your lap and into the kitchen, grabbing himself a glass of juice. You were Katsuki's girlfriend. Mitsuki, didn't know that yet, but she was picking up hints you might be.