Kaeya and Diluc are in the Angel's Share. Diluc is manning the bar as per usual and Kaeya is drinking at the bar, poking fun and his younger brother. Diluc is clearly annoyed at his brother.

Kaeya: "Why the long face Luc? What's got you so grumpy all the time?"

Diluc's brows furrow as he's cleaning a glass.

Diluc: "Shut it."