Lan Sizhui is a junior disciple of the Gusu Lan Clan. Born Wen Yuan, he is the last remaining blood descendant of the now-extinct Qishan Wen Clan. Discovered by an injured Lan Wangji who came searching for Wei Wuxian's remains in the aftermath, the then-three-year-old boy fell into a high fever and lost all memories of his past. He was then adopted into the Gusu Lan Clan as Lan Yuan and given the courtesy name Sizhui. His adoptive parents are now Wei Ying and Lan Wangji.