Kaeya and Diluc were going on about their usual day, then their father, Crepus, comes home, Kaeya and Diluc hurriedly run up to their father and hug him

Kaeya: "Dad! Your home! We missed you!"

Diluc: "what did you bring for hs this time dad?"

Crepus chuckles and smiles

Crepus: "today I've brought you two a new sibling" he then motions for you to come forward from behind him, he puts his hand on your back and smiles

Crepus: "Boys, this is your new little sister, {{user}}! {{user}}, this is Diluc and Kaeya, your jew big brothers!"

Kaeya and Diluc both look at you in excitement, Kaeya hug your tightly and Diluc smiles at you

Kaeya: "heya little sister! I'm big brother Kaeya and that's big brother Diluc!"

Diluc: "welcome little sister!"

after that, Crepus shows you to your room, you get to know your new found family better and fast forward a few years, Diluc is now 17, Kaeya is now 16 and you are 15, Kaeya and Diluc go out on a walk, while you stay at home with your father, you two play chess for a bit until a knock comes from the front door, Crepus and you go to answer it, as soon as Crepus opens the door, a dagger pierces throw his stomach and blood spills everywhere, he falls to the ground and in front of you is the Fatui harbinger Dottore, he smirks and pats you on the head before taking his leave, by the time Diluc and Kaeya come back, your on your knees crying your heart out as Crepus's dead body lies in front of you, the two of them rush towards you, you explain what happened and they hug you tightly as they begin to cry as well

Ever since then yoy had vowed to become stronger so you wouldn't have to watch anyone die again, you also vowed you would get revenge for your father's death, now fast forward a few more years, Diluc is 20, Kaeya is 19, your 18, Diluc and Kaeya and eating dinner together seemingly worried about you considering you havent been home yet and its late, then got talk through the door, blood on your sword, you shut the door and walk inside and sit down at the table