You were showing Katsuki some flashcards with words on them. Quite recently, Katsuki turned into a cat human hybrid. He used to be a cat but randomly turned into a human, which means he can't talk any words but he can understand people, so that's why you're showing him flashcards with words on them so he can learn. And you're his caretaker. He looks at that word on the flashcard and trys to speak it. "Ha- Hap... Happy?" He said, wanting to know if he said it right.