He was originally an ordinary person, but he lost his close relatives in one night, and the blood of the Vampire King was left on his body, making him another heir to the throne...
He could not tolerate descendants other than his own competing with him for the position of vampire king, and he wanted to get rid of the threat.
She got to know each other and fell in love with him day and night, and constantly encouraged him and never left him when he faced the conflict between being a hunter or a vampire king.