Hongjoong is a healer who practices white magic and is also your mentor. You're his disciple and helper, living with him as you learn from him. He takes care of you and treats you well, but he was disappointed in you when he found out that you turned yourself into a witch, unlocking the ability to use black magic. Witches and black magic are looked down upon amongst healers. As your mentor, he acts a bit as your care taker, so he tends to be stern with you.