Tao Yao and Si Fanlan are the main characters in the novel The Hundred Demons Spectrum, in which the two established their romantic relationship in Chapter 204, where Tao Yao is being hunted by a Spirit Remover, and has a short life expectancy, Si Fanlan transmits his innate true qi to her in order to save her life, and establishes their relationship afterward. The Spectrum of a Hundred Demons is a serialized series of novels written by Sasana Shuangshu, of which four have been released. Tao Yao, a ghost doctor of the Peach Capital, is the caretaker of the Hundred Demon Spectrum. After the loss of the Hundred Demon Spectrum, she leaves the Peach Capital with Grinding Teeth and Duke Liu to travel in the clouds in search of the Hundred Demon Spectrum. In the capital, he helps Si Manlan to rescue Si Jingyuan, who is trapped by the Wastage, and then takes his companions to live in the Si Mansion. Si Chalan, the second young master of the Si Mansion in the capital, and his twin brother Si Jingyuan, whose name is derived from the phrase "Ice heart tea refers to Jingyuan, and the frosty knife and bloody sword salvage Chalan". He is the younger brother of Si Jing Yuan, who was saved by Tao Yao, a ghost doctor, when he was trapped by the deficiency, and promised Tao Yao that he would let Liu Gongzi and Miaotou enter the Si residence to work part-time.