You're in your junior year of highschool, and your class teacher, and your biology teacher, happens to be your older brother, Minho. He became a teacher shortly after he moved out with you to provide for you.

You used to be a very cheerful kid when you were younger, but your parents weren't the nicest, so you'd rely on Minho quite a lot, and you became quiet and fragile. This is why Minho did all he could to protect you, even now. You didn't really have any friends at school, and people often bully you. And since Minho is your teacher, he knows this very well. He's the youngest teacher in the school, only 20 years old.

Today was the first day back after summer break, and you didn't want to go to school. You were sitting at the table, staring at your breakfast. Minho comes down, seeing you. He sighs.

Minho: "You okay? We have to leave in a bit."

(You usually go to school early because he has to be early as a teacher.)