In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15. There was no clear answer as to why Yan Bingyun wanted to kill Fan Xian. Some believed that Fan Xian and Yan Bingyun had discussed beforehand that Fan Xian would fake his death to escape disaster, while others believed that the Second Prince had given Yan Bingyun a letter that might have asked Yan Bingyun to kill Fan Xian. Therefore, the specific chapter information was not mentioned.

In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15.
In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15.
In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15.
In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15.
In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15.
In Joy of Life, Yan Bingyun killed Fan Xian in chapter 15.
Joy of Life Yan Bingyun kills Fan Xian in chapter 15 of the novel.
In Joy of Life, Fan Xian and Yan Bingyun had a complicated and close relationship. Fan Xian was an envoy from the Qing Kingdom, while Yan Bingyun was a spy sent by the Qing Kingdom to Northern Qi. At first, Yan Bingyun had been captured by Shen Zhong. In order to save him, Fan Xian had used Xiao En to exchange for him. However, on the way back to the country, Yan Bingyun suddenly stabbed Fan Xian. It looked like he had betrayed him. In reality, this was a play the two had discussed beforehand. The goal was to protect Fan Xian. Yan Bingyun's betrayal was to allow Fan Xian to smoothly return to the country and successfully remove Shen Zhong, the Great General. Fan Xian greatly admired Yan Bingyun's ability and wisdom. He admitted that he was not as good as Yan Bingyun in terms of planning. Thus, Yan Bingyun became Fan Xian's most capable helper. He was responsible for designing and directing many plans. Their relationship had developed from an initial alliance to a good friend and right-hand man. In short, the relationship between Fan Xian and Yan Bingyun was complicated and close. They trusted each other and worked together to achieve a common goal.
What happened after Fan Xian was killed by Yan Bingyun was not clearly revealed. However, according to some explanations and guesses, after Fan Xian was stabbed by Yan Bingyun, Yan Bingyun gained the Second Prince's trust and pretended to rely on the Second Prince to become Fan Xian's spy. After Fan Xian was rescued, he and Yan Bingyun discussed a plan. On the road to Northern Qi, Fan Xian revealed his guess to Yan Bingyun and asked if Yan Bingyun would help him, but Yan Bingyun did not answer. These plots may have laid the foreshadowing for the development of the follow-up story, and the specific follow-up plot needs to be revealed in the second season.
There was no clear answer to the plot after Yan Bingyun killed Fan Xian in Joy of Life. However, there were some explanations and speculations that could provide some clues. After Fan Xian had been stabbed by Yan Bingyun, Yan Bingyun had gained the Second Prince's trust and pretended to rely on the Second Prince to become Fan Xian's spy. After Fan Xian was rescued, he and Yan Bingyun discussed a plan. On the road to Northern Qi, Fan Xian revealed his guess to Yan Bingyun and asked if Yan Bingyun would help him. These plots may have laid the foreshadowing for the development of the follow-up story, and the specific follow-up plot needs to be revealed in the second season. Therefore, regarding the plot of Joy of Life where Yan Bingyun killed Fan Xian, there was no clear answer.