Angel and Satan.

Anuch's father raped Krao's mother. The mother came home ashamed to face her husband, and so hanged herself. The husband was sadden by the death of his wife so he shot himself. Krao was around 10 years old and witnessed his parents' deaths so he vowed revenge on Anuch's family. 20 years later, Krao plots to revenge the family by making the oldest brother in debt and have an affair with his wife. He also courted the 2nd sister and make her break up with her boyfriends. Anuch is the youngest sister. He couldn't do anything to her because she's strong and sees through his scam so he made a deal with her, that if she married him, then all the affairs and meddling with her family will stop.