I don't know which novel you're referring to, but can you provide more context or description so that I can better answer your question?
The specific plot of Xu Xiao calling Zhenwu the Great Emperor's son in Sword Snow Stride " was not mentioned. "Therefore, according to the information provided, I don't know if Xu Xiao calls him Zhenwu Great Emperor's son.
Zhenwu Great Emperor was the god of the north in Chinese Taoism and folk belief. He was also a famous god among Taoist immortals. He had many nicknames, such as the Mysterious Heavenly God, the Blessed Saint True Lord, and the Black Tortoise Great Emperor. Zhenwu Great Emperor held an important position in Chinese folk beliefs, especially in Wudang Mountain in Hubei Province. He was known as the 'Heaven Suppressing True Martial Emperor' or 'True Martial Emperor' for short. Zhenwu Great Emperor was known as the God of the North and the God of Water. He was also one of the Four Sages of the North Pole. His appearance was fierce. He was wearing a black robe and a golden armor jade belt. He held a sword and glared angrily. He was standing on a five-colored spiritual turtle with a round light covering his head. Zhenwu Great Emperor was described in the Taoist classics as a god who ruled over the heavenly soldiers and generals and suppressed the demons of the three worlds. His temple and dojo were mainly in Wudang Mountain in Hubei Province.
Zhenwu Great Emperor was respectfully addressed as the founder. He was the god of the north in Chinese mythology and was also the famous god of Jade Capital in Taoism. Zhenwu Great Emperor's full name was Zhenwu Devil-rinsing Great Emperor, also known as Xuantian God, Xuanwu Great Emperor, Protector Saint Perfected Lord Xuantian God, Devil-rinsing Heavenly Lord, etc. In Taoism, he was revered as the ancestor of gratitude, representing the spirit of gratitude and filial piety. In Wudang Mountain in Hubei Province, the main god worshiped was Zhenwu Great Emperor. His appearance was mighty. He was a hundred feet tall, with loose hair and golden armor. He stood on a five-colored spiritual turtle, pressed his sword, and his eyes were like lightning. Zhenwu Great Emperor attached great importance to filial piety in his cultivation, so he was honored as the Sect Master of Repaying Gratitude. Every year, the third of March was his Christmas, and it was celebrated as the birthday of the Martial Ancestor. In short, Zhenwu Great Emperor was an important god in Taoism and was called the founder by the people.
Zhenwu Great Emperor, also known as Xuantian God, Yousheng Zhenjun, Xuanwu Great Emperor, etc., was the god of the north in Chinese mythology and was a famous god among Taoist immortals. His dojo was located in Wudang Mountain in Hubei Province. Zhenwu Great Emperor had the characteristics of the God of the North and the God of Water. His appearance was mighty. He was a hundred feet tall, with loose hair and golden armor. He stood on a five-colored spiritual turtle and held his sword. His eyes were like lightning. He was the incarnation of Grand Supreme Elder, reborn in Jingle Palace of Jingle Nation. Zhenwu Great Emperor held an important position in Chinese folk beliefs. He was known as the Devil-rinsing Primogenitor, the Patriarch of Repaying Gratitude, and the Patriarch of Hair. After the Ming Dynasty, he had a great influence in the country. In modern times, folk beliefs were especially common.
Xu Fengnian was the reincarnation of Zhenwu Great Emperor. In the novel, Sword Snow Stride," Xu Fengnian was revealed as the true body of Zhenwu Great Emperor. Although many viewers thought that Xu Longxiang or Hong Xixiang were the reincarnation of Zhenwu Great Emperor, Xu Fengnian was actually the real reincarnation of Zhenwu Great Emperor. Xu Fengnian began to practice martial arts and saber arts after traveling in Jianghu. He also honed his martial arts under the waterfall of Xuanxian Peak in Wudang Mountain. On Zhenwu's Demon Subduing Day, Wudang Sect Leader Wang Chonglou had passed on his Great Yellow Court to Xu Fengnian, greatly improving his cultivation. Xu Fengnian's identity caught the attention of Wudang Mountain. He was recognized as the reincarnation of Zhenwu Great Emperor. Therefore, Xu Fengnian was closely related to Zhenwu Great Emperor.
Xu Fengnian was the reincarnation of Zhenwu Great Emperor. Xu Fengnian was revealed to be the true body of Zhenwu Great Emperor in Sword Snow Stride ". Although many viewers thought that Xu Longxiang or Hong Xixiang were the reincarnation of Zhenwu Great Emperor, Xu Fengnian was actually the real reincarnation of Zhenwu Great Emperor. Xu Fengnian began to practice martial arts and saber arts after traveling in Jianghu. He also honed his martial arts under the waterfall of Xuanxian Peak in Wudang Mountain. On Zhenwu's Demon Subduing Day, Wudang Sect Leader Wang Chonglou had passed on his Great Yellow Court to Xu Fengnian, greatly improving his cultivation. Xu Fengnian's identity caught the attention of Wudang Mountain. He was recognized as the reincarnation of Zhenwu Great Emperor. Therefore, Xu Fengnian was closely related to Zhenwu Great Emperor.
Xu Fengnian was the reincarnation of Zhenwu Great Emperor. Xu Fengnian was the Great Emperor Zhenwu who descended to the mortal world. His true body was the Great Emperor Zhenwu. He chose to cut off the connection with his previous life and lost the ability to use Zhenwu Great Emperor's power, but he also got rid of the connection with his previous life. Xu Fengnian's identity in the human world was the heir of the Prince of Beiliang. He was known for his silkpants image, but in fact, he had a deep heart and a good plan. Therefore, Xu Fengnian was the reincarnation of Zhenwu Great Emperor.
Zhenwu Great Emperor's subordinates included the four marshals. They were Marshal Ma, Marshal Zhao, Marshal Guan, and Marshal Wen. These four marshals played the role of guardians in Taoism and played an important role in the spread and maintenance of Taoism. They were known as the Guardian Marshals of Zhenwu Great Emperor and used their might to suppress the Dao Sect.
Zhenwu Great Emperor's four disciples were Yang Zhi, Yu Dulong, Wang Sheng, and the land flood dragon.
Zhenwu Great Emperor was known as the Ninth Heaven Devil-rinsing Patriarch, and he was extremely powerful. He was more than a hundred feet tall and had a mighty appearance. He wore a black robe and a golden armor jade belt. He held a sword in his hand and stood on a five-colored spiritual turtle. A round light shone on his head. He conquered all the evil spirits in the world and even subdued the evil spirits in the east. He controlled the Black Tortoise, wore golden armor, and subdued all the evil spirits in the world. Zhenwu Great Emperor had many titles, such as Xuantian God, Nine Heavens Devil-rinsing Patriarch, and North Pole Xuanling. He was one of the Five Elders of the Five Directions, and his status in the Heaven Realm was comparable to Tathagata and Guanyin. His strength was so powerful that all the demons had to bow down to him, and all the demons had to submit to him. He was known as the number one war god of the Heavenly Court. His black flag was even more powerful. It could block the entire Heavenly Court and make the demons of the Three Realms fear it. All in all, Zhenwu Great Emperor was a very powerful existence.