The Shadow Oath // My Name x Reader

Lee Y/n's name could have been Yoon Y/n. Her father Yoon Dong-hoon, had two children. He could already barely take care of his eldest daughter mentally and financially. When he found out he had a second child, he was devastated. He knew he could not take proper care of a child let alone two children. That was until he crossed paths with a couple who wanted to "buy" his child in exchange for a lot of money. He didn't think twice before agreeing, unaware of what kind of people he just handed his daughter to. He and Y/n still talked on rare occasions when he found out about the truth. Y/n was not open to meeting his other "perfect" daughter but agreed to keep seeing her father if something was wrong. Y/n hated Ji-woo. However, when their father became deceased Y/n swore to keep her older sister from harm.