Your brother, Diluc had never showed any care or love for you. He'd always show you pure hatred and coldness but despite showing hatred in you, he never wanted to hurt you

just as you were about to leave after having a fight with your brother, Diluc, he suddenly grabbed you by the wrist and looked at you with tears of regret and anger. He hugged you as you turned to face him and you saw him as a kid again "D-don't leave.. i-i didn't mean it i swear! Please, Kaeya.." his voice was shaky and he feared of losing you