In Joy of Life, the person who ordered Lin Gong to kill Fan Xian was the Eldest Princess, Li Yunrui.

The Eldest Princess Li Yunrui was the one who ordered Lin Gong to kill Fan Xian.
Lin Gong's assassination of Fan Xian was ordered by the Eldest Princess, Li Yunrui. In his view, it was basically impossible for Fan Xian to truly control the wealth of the palace treasury. Fan Xian's enemy was the future Emperor, the Crown Prince. After Lin Gong passed away, Minister Lin found Fan Xian and brought him to his study. He showed Fan Xian Lin Gong's calligraphy from when he was a child. When Lin Gong was eight or nine years old, he was already very good at calligraphy and had great ambitions. He hoped to make great achievements in the future and bring glory to his family. Lin Gong knew from a very young age that his elder brother was a fool and his younger sister was a phthisis patient. As the only healthy person in the family and a male, he had to live for the whole family. It was a very heavy responsibility. Before Fan Xian had appeared, he had relied on the Crown Prince and Eldest Princess. Later, the Qing Emperor arranged the marriage between Lin Wan 'er and Fan Xian. Only then did things change a little. However, Lin Gong did not know the truth about Fan Xian's background.
According to reference 1 and 3, the Second Prince had ordered Lin Token to kill Fan Xian, but Wan 'er did not know. During Fan Xian's wedding, the Second Prince had told Wan 'er of Lin Token:1841Token:375's death, attempting to make Wan' er kill Fan Xian in anger.
Lin Gong was not killed by Fan Xian, but by Wu Zhu. Lin Gong was the villain in Joy of Life. He planned the Niulan Street assassination, which resulted in the death of Fan Xian's guard, Teng Zijing. Fan Xian had wanted to take revenge on Lin Gong, but Wu Zhu stopped him. In the end, Wu Zhu personally killed Lin Gong. Therefore, Lin Gong's death had nothing to do with Fan Xian.
Lin Gong wanted to kill Fan Xian because he had come to the capital to rob the Eldest Princess of her palace treasury and marry Lin Gong's sister, Lin Wan 'er. This made Lin Gong very angry. Lin Gong was Lin Wan 'er's older brother, and also the Crown Prince and Eldest Princess's man. He believed that it was basically impossible for Fan Xian to truly control the wealth of the palace treasury because Fan Xian's enemy was the future Emperor, the Crown Prince. In addition, Lin Gong was also instructed by the Eldest Princess Li Yunrui to persuade Lin Gong to assassinate Fan Xian. Thus, Lin Gong arranged for Cheng Jushu to assassinate Fan Xian.
Fan Xian did not kill Lin Gong. Lin Gong was killed by Wu Zhu, not Fan Xian. Fan Xian had once been suspected of being the murderer of Lin Gong's death, but Minister Lin later learned the truth. He knew that Lin Gong was the mastermind behind the Niulan Street assassination, not Fan Xian. Thus, Lin Gong's death had nothing to do with Fan Xian.
Fan Xian did not kill Lin Gong. Lin Gong was killed by Wu Zhu, not Fan Xian. Fan Xian was the brother of Lin Gong's fiancée, Lin Wan 'er. He wanted to kill Lin Gong in revenge for the Niulan Street assassination planned by Lin Gong, but after Wu Zhu found out, he stopped Fan Xian and personally left the capital to kill Lin Gong. Lin Gong's death had nothing to do with Fan Xian.
Lin Gong wanted to kill Fan Xian because he had been instructed by the Eldest Princess, Li Yunrui. Lin Gong believed that Fan Xian could not truly control the wealth of the palace treasury because Fan Xian's enemy was the future Emperor and Crown Prince. In addition, Lin Gong did not want Fan Xian to marry his sister, Lin Wan 'er. After Fan Xian learned the truth, he decided to take revenge, but he was also hesitant. Killing Lin Gong would mean losing Lin Wan 'er. In the end, Fan Xian received Wu Zhu's help. Wu Zhu killed Lin Gong. Lin Gong ended up being killed by Wu Zhu.
Fan Xian killed Lin Gong. At first, Fan Xian hesitated whether to kill Lin Gong because he was the sister of the girl he liked. Killing Lin Gong meant losing the girl he loved. However, Wu Zhu saw Fan Xian's dilemma and made a decision on his behalf to kill Lin Gong. Fan Xian was very angry about this, indicating that he was more inclined to have a girl than a brother. Thus, according to the information provided, Fan Xian killed Lin Gong.
Fan Xian killed Lin Gong because Lin Gong was his enemy, and Fan Xian wanted to avenge his friend Teng Zijing. Although Fan Xian also liked Lin Gong, he could not tolerate his betrayal and harm. In addition, Fan Xian's robot Wu Zhu also helped him make this decision. Fan Xian was more inclined to protect his friends than to pursue feelings.