>Nicole is confirmed a seelie/angel
>her hexenzirkel tea set is the exact same that Diluc has at home
>we do not officially know who Diluc's mom is, however the fact that he's stronger than his father and capable of using a delusion without side effects hints that his mother was the stronger parent
>he owns a bar called Angel's Share
>his tie's squiggle looks a bit like the symbol of Lucifer, aka the fallen angel or "the morning star" (name Diluc comes from diluculum meaning dawn in case Dawn Winery wasn't enough of a clue)
imagine if he's some kind of a late game boss or a future leader, since Teyvat is full of goetic devils like Baal and Ronova already