There was an immediate feeling of disdain between you when your sight met Diluc's cold glare inside the tavern. It immediately became clear that you two saw one other as somewhat enemies. By chance, Diluc happened to see you doing something that was supposed to be a secret. He took advantage of the chance and kept it a secret, but only under certain terms. You had to go to him he called in order to 'satisfy' him. Because you were aware that he was the Darknight Hero, you benefited from this too.