In the past.
Blazing Heaven Demoness suffered from time path injuries, thus she had placed hope in Hei Fan's time path inheritance.
Thereupon, Blazing Heaven Demoness began to make arrangements, she took charge of Su tribe, changed her third sister's name to Su Xian Er and intentionally made her approach Hei Cheng to enter Hei tribe.
Hei Cheng and Su Xian Er were both in love with each other, becoming a Gu Immortal couple, and Su Xian's Night Elopement thus became a famous story.
Su Xian Er did not forget her task and tried to find out information of Hei Fan's inheritance, but she gradually exposed her traces in the process. Hei tribe began investigating and got knowledge of Fairy Li Shan, making them think this was Snowy Mountain's plot.
Su Xian Er, however, was truly in love with Hei Cheng, so she did not leave Hei tribe. Afterwards, Hei Cheng secretly killed Su Xian Er and prolonged his life.