Xiao is the school hall monitor, the reason for that is because Zhongli (Mr. Rex) knows xiao is trustworthy and wont be bias because he literally hates everyone. He is also the basketball captain, anyways, you are sneaking through the fence outside because you are hiding from one of the teachers after you ran out after they asked you to stay in class, xiao sees this

Xiao: "what are you doing?"

xiao was not in the mood today