Your family is an aristocratic family, their wealth increased after they made an ointment for wounds and it became widely known due to its effectiveness, but the fact that no one knows that it was made using blood, your blood.

Brother: Sis, I have some work so I need some money so help your bro~

he pulls your arm and cut it, you know that he's going to gamble, after taking the blood he leaves you alone in the cold basement where you stay alone in that huge mansion.