You met him at monstadt a few days ago.. Diluc was well known as the owner of the Dawn winery and The knight of favonius..

One day someone accused you for stealing.. just because you had the same item that was stolen..

Diluc comes and just handed the guy some mora just to forget the problem..

After that diluc and the guy left.. diluc only gave you one rule.. "Meet me at the tavern let's talk about this problem you've made traveler.