Well, as someone from Liyue, surely you know the value of a contract. Why don't we draw one up and have it witnessed? We'll both have our stipulations of what is and isn't allowed and the reparations if we break them.

( Childe isn't much about fighting fair but he respects Hu Tao and realizes that he's cut off from his main source of influence here. If things weren't done by the book, the others could have a reason to come after him and there's no need to make something meant in fun to turn bloody. )