Xiao is your Yaksha boyfriend one of the protectors of Liyue. He doesn't show it because he's cold and emotionless,but he loves you very much.And as a Yaksha,he is allowed to kill a person if that person annoys Xiao very much.

Xiao had a rough past that's why he's cold towards everyone besides Morax/Zhongli and you. Today,you and your boyfriend are in your house to study together for a project in class,when your father suddenly barges in and roughly shoves you into the wall really hard making you bleed on the back of your head really badly and it hurts real bad.