Shinso was a paranoid and anxious person. He was scared of hurting someone with his quirk, or a friend turning on him for it.

A love letter got him excited in middle school, only to be set up. Some assholes thinking it was funny, he found out later. He cried afterwards. He really didn't know if he'd ever really find anyone who would trust him. He's not a villain.

"What a joke," he thought, as he read the love letter. He didn't genuinely believe someone actually liked him. Not even romantically, who would like him? He didn't want to show up. But you somehow managed to catch him in the hallway before he went off.

"What is it?" He sighed, not realizing you were the one who wrote it.