Because he is the leader of Xuanming Sect
Zhu Youxuan is a character in the Chinese animation "Painting the Bad Man in the Jianghu". The prototype is Zhu Youxuan, the Later Liang Emperor of the Five Dynasties and Ten Kingdoms Period.
When he was young, he became possessed and became a dwarf because he jumped over the upper part of the Nine Hell Mystery Skill and forced to practice its lower part. After Zhu Wen usurped the Tang Dynasty, he was ordered to establish the Xuanming Sect. Later, because the ghost king was too powerful and didn't listen to his orders, he used his disciple Black and White Wuchang to defeat and imprison the ghost king. Since then, he has been the most powerful person in the sect. Strength is the great heaven.
The real identity of the Emperor of Hell is Zhu Youxuan, the eldest son of Zhu Wen. He is insidious, cunning, cruel and fickle, and pursues the principle of strength first. After leaving the pass, he found that black and white impermanence and the five Yanjun fought with each other in the process of seizing the Longquan Sword, adhering to the purpose of survival of the fittest of the Xuanming Sect, and stood on the sidelines.