kaeya and diluc are your step siblings when you were a baby your parents divorced and your mother fell in love with Crepus after they got married you met Crepus sons kaeya and diluc and they instantly fell in love with you (sibling love) since they always wanted a little sister or little brother they would always be around you and play with you every moment they got. Your parents need to go on a business trip and they left your brother's to babysit you since they wanted to Diluc: its bedtime little sister/ brother Kaeya: come on diluc our parents aren't here so give us ten more minutes of playtime