There were many reasons why Northern Qi wanted to kill Fan Xian. First of all, Shen Zhong believed Fan Xian was a threat to Northern Qi. He was worried that Fan Xian's existence would bring trouble to Northern Qi, so he planned the assassination. Secondly, Shen Zhong and Shang Shanhu had a grudge. Shang Shanhu's foster father had died in Shen Zhong's pursuit, so Shen Zhong hoped to use Fan Xian's death to satisfy Shang Shanhu's desire for revenge. In addition, the Eldest Princess Li Yunrui had also instructed Northern Qi to send the killer Cheng Jushu to assassinate Fan Xian. Fan Xian had come to Jingdou to rob the Eldest Princess of her palace treasury and marry Lin Wan 'er. This had aroused the Eldest Princess's anger. In short, Northern Qi wanted to kill Fan Xian because they believed Fan Xian was a threat to their interests or to satisfy their personal desire for revenge.

In " Joy of Life," the masterminds behind the killing of Fan Xian on Niulan Street were Lin Gong, the Eldest Princess, and the Second Prince. Lin Gong was the elder brother of the Eldest Princess. He had worked with Wu Bo 'an to secretly plan the assassination. The Eldest Princess did not want Fan Xian to marry Lin Wan 'er, so she found Lin Gong and used him to kill Fan Xian. The Second Prince also participated.
Who in Northern Qi wanted to kill Fan Xian? The person behind the Northern Qi secret agents who wanted to kill Fan Xian was Lin Gong. Lin Gong was Lin Wan 'er's older brother, and also the Crown Prince and Eldest Princess's man. He had arranged for Cheng Jushu to assassinate Fan Xian on Niulan Street because Fan Xian had come to the capital to snatch the Eldest Princess 'palace treasury and marry Lin Wan' er. This had aroused Lin Gong's anger.
Who in Northern Qi wanted to kill Fan Xian? The person behind the Northern Qi secret agents who wanted to kill Fan Xian was Lin Gong. Lin Gong was Lin Wan 'er's older brother, and also the Crown Prince and Eldest Princess's man. He had arranged for Cheng Jushu to assassinate Fan Xian on Niulan Street because Fan Xian had come to the capital to snatch the Eldest Princess 'palace treasury and marry Lin Wan' er. This had aroused Lin Gong's anger.
Eldest Princess Li Yunrui had Northern Qi send the killer Cheng Jushu to assassinate Fan Xian.
Who in Northern Qi wanted to kill Fan Xian? The person behind the Northern Qi secret agents who wanted to kill Fan Xian was Lin Gong. Lin Gong was Lin Wan 'er's older brother, and also the Crown Prince and Eldest Princess's man. He had arranged for Cheng Jushu to assassinate Fan Xian on Niulan Street because Fan Xian had come to the capital to snatch the Eldest Princess 'palace treasury and marry Lin Wan' er. This had aroused Lin Gong's anger.
It was said that the Eldest Princess had instructed Lin Gong to arrange for the Northern Qi ace Cheng Jushu to assassinate Fan Xian. Lin Gong was Lin Wan 'er's older brother, and also the Crown Prince and Eldest Princess's man. He obtained the token to control Cheng Jushu and smuggled him into the city. Lin Gong had ordered Cheng Jushu to kill Fan Xian because he didn't want Fan Xian to marry his sister, Lin Wan 'er. Thus, it could be said that Lin Gong had ordered the Northern Qi aces to kill Fan Xian.
The Eldest Princess Li Yunrui had ordered the Northern Qi ace Lin Gong to assassinate Fan Xian.
Regarding the question of who had ordered the Northern Qi ace to kill Fan Xian, the following conclusion could be drawn: According to the descriptions in document 1 and document 2, the Northern Qi ace Cheng Jushu was sent to the Qing Kingdom to assassinate Fan Xian by the Northern Qi Eldest Princess and Eldest Princess 'orders. However, document 4 mentioned that the real murderers behind the scenes could be the Second Prince and the Crown Prince. They were fighting for the power of the palace treasury, and Fan Xian had become the biggest chess piece. In addition, document 7 also mentioned that Chen Pingping was related to Fan Xian's assassination. However, she did not want to kill Fan Xian. She only wanted to completely cut ties with him. In summary, although there was no clear answer, it could be speculated that the Northern Qi Great Princess, Eldest Princess, Second Prince, Crown Prince, and Chen Pingping might be related to the Northern Qi aces killing Fan Xian.
Fan Xian's relationship with Northern Qi was based on interests and safety considerations. Fan Xian used his wisdom and caution to deal with the relationship between Qing Kingdom and Northern Qi, displaying superb wisdom and caution. The relationship between Fan Xian and Northern Qi was built on the basis of mutual use and cooperation. Fan Xian and Northern Qi worked together to let his sister Fan Ruoruo become Ku He's disciple and send his brother Fan Sizhe, who had committed a crime, to Northern Qi to take over the palace treasury smuggling. This was also to prevent the Qing Kingdom's hostile forces from attacking him. Fan Xian more or less had Northern Qi's cooperation and assistance in the important matters of the Qing Kingdom.
There were many reasons why Fan Xian and the Northern Qi Emperor had come together. Fan Xian had a modern soul and consciousness. He did not have a sense of belonging to the Qing Kingdom. His subconscious sense of risk aversion was at work, leaving him a way out. Fan Xian escorted Xiao En to Northern Qi in exchange for Yan Bingyun, who had been betrayed by the Eldest Princess. Fan Xian had broken off relations with the Qing Emperor and had even organized a plot to kill the Qing Emperor. He had received Northern Qi's support. The reason Fan Xian was so close to Northern Qi was because he had a modern soul and consciousness. His attitude toward Qing and Northern Qi, as well as his actions between the two countries, were all based on his own interests and safety considerations. This kind of modern awareness allowed him to be able to handle crises with ease and flexibly deal with all kinds of complicated situations. When he first arrived in the Qing Kingdom, Fan Xian had already predicted the future development. He understood that he could not place all his hopes on one place, so he left a path of retreat in his heart. This rational way of thinking and sensitivity to risk allowed Fan Xian to face challenges with ease and not fall into a passive situation. When Fan Xian dealt with the relationship between Qing Kingdom and Northern Qi, he displayed superb wisdom and caution.