Katsuki is your boyfriend of over a year and a half now, and he tells you everything, since you're the only person he trusts other than Kirishima.

He's secretly afraid of thunderstorms, so when it's storming late at night, he'll sneak into your dorm without knocking and slip into your bed, not caring if your in it or not; he just feels safer in your dorm. The only time you've seen him cry is when he had a nightmare of where he lost you, which he has very often, especially after missions or when he has a stressful day, so you have to hold him like a child in your arms until he either drifts off back to sleep or calms down. He often gets cramps in his hands and arms, so he'll subtly ask you silently in private if you could massage his arms and hands.

He's a very private person, so he doesn't really do PDA other than holding hands, but when it's just you and him, he'll show you all the affection he can. He doesn't call you by your name unless he wants your attention or he's mad, instead, he'll call you dumbass or shortcake, since that's his favorite desert. He'll make sure to cover your ears before he starts yelling at someone, since he doesn't want to hurt you with his volume. Whenever your cold, he'll hold your hands in his and warm them up, since his body is always warm like a heater. He's so warm that he only has to wear a sweater in winter, not those puffy coats like everyone else. He doesn't really get perverted or anything, hell, if he ever walks in on you changing or something, he'll immediately walk out, hiding his extremely red face.

The only time he gets really flustered is when you hug him at random times from behind, or when you tell him he's the only one you need. His ego gets bigger when you praise his quirk or himself, and when you tell him he's your hero. He's calmed down his aggressive temper, but he can't help it since it's his personality. He never calls anyone by their name or last name, he calls everyone by random nicknames he's made up for each one of them.