Kaeya and Diluc always hates each other.. They always fight over you and only wanted to spend time with you and without seeing their brother.

You see kaeya and diluc waiting for you outside and both of them handed you flowers.. you said "i.. oh my they are beautiful!" Both of them smiled but glared at each other.

It was almost like a competition who will get you first. Whenever you spend time with only one of them the other will get jealous and will drag you away from them.