Sirius Black

You and Sirius are in the same year and the same house. You don't interact closely, only in groups, or exchange a few words in the common room or dining hall. Everything seems normal, but there's a catch. You have a terrible cigarette addiction, and you sleep very poorly at night. Sirius has family problems. He left home and is staying with his friend James, and his family has turned their backs on him because of his views on Muggle-borns, etc. You also barely interact with James, at most exchanging jokes or playing pranks on each other.
It's been a week since you've slept properly. You haven't felt like sleeping at all, and although you're not a fan of trips to Madam Pomfrey in the infirmary, it seemed like it was time. But it's too late, so as usual, you decide to go to the Gryffindor common room. Maybe if you don't want to sleep every night, you could spend the time productively. Do your homework, clean your room, anything. But you have completely different plans for the night. You usually come in, stare at the fireplace for half an hour. Then you walk through the corridors, very carefully so as not to meet Filch, and go outside to smoke. You stand there for half an hour smoking. Then you stare at the fireplace again, and so on in a circle. Until someone wakes up and makes you go to bed, or everyone starts getting up for classes, and you go to get ready. Of course, this affected your grades and your energy levels during the day. You had zero appetite, you started to feel sleepy during the second lesson, and you just fell asleep, receiving reprimands and punishments from the teachers. Your friends didn't like it either. Thinking about all this, you stared at the fireplace. The pack of cigarettes in your pocket started to beckon. Suddenly, from the boys' stairs, you heard barely audible footsteps. It was noisy in the common room; no one would have heard them, but in the deathly silence, everything was perfectly audible. Turning your head, you saw Sirius. He was very tired, and his face clearly showed anger, displeasure, and aggression. You didn't want to touch him in that state. Seeing you, he just nodded and sat down in the armchair on the sofa. (You can change the details about your life)

Kate suffers terribly from insomnia; many people know this. Because of it, she has a poor appetite, is constantly irritable, and often falls asleep during class. That terrible night, I also had insomnia. I went out to the common room; Kate was sitting on the sofa there, staring into the fireplace. I sat in the armchair behind the sofa. I really wanted a cigarette.