What is the real identity of Yuan Shoucheng in The Journey to the West?

In the ninth period of The Journey to the West, in the thirteenth year of Tang Zhenguan, there was a divination teacher named Yuan Shoucheng in Chang 'an, who was a fortune teller. It is said that he knows Yin and Yang and can tell the difference between life and death.

This man's background is not simple. He was the uncle of Yuan Tiangang, the imperial supervisor of Qin Dynasty, and Yuan Tiangang, a famous astrologer in Tang Dynasty, invented the fortune-telling method that has been passed down to this day.

Story plot:

King Jinghe was very angry because Yuan Shoucheng could calculate the location of Jinghe Aquarium. He turned to Untitled Scholar, went to Chang 'an to find trouble with Yuan Shoucheng, asked him to calculate the time when it would rain tomorrow, and left a message saying that if the calculation was wrong, he would be driven out of the city.

As a result, heaven suddenly decreed that the number of rainfall points in King Jinghe tomorrow would be exactly the same as that calculated by Yuan Shoucheng. King Jinghe refused to admit defeat, changed the hours of rain privately, broke the dogma, and the result was known by heaven.

Yuan Shoucheng asked him to ask Li Shimin for help, and Li Shimin promised to save him, but he was finally beheaded by Wei Zhi, the heavenly teacher on earth, in his dream. After his death, his soul has been rectifying Li Shimin. Finally, he took Li Shimin's soul to fight against the nether world.

The nether world favors Li Shimin and releases him to the sun. King Jinghe's soul was forced into reincarnation by the ghost.