Mo Xuanyu (莫玄羽, Mò Xuányǔ) was one of Jin Guangshan's illegitimate sons and a former disciple of the Lanling Jin Sect. He sacrificed his soul to summon an evil spirit, Wei Wuxian, to exact revenge on the Mo family on his behalf. In his living days and even during Wei Wuxian's possession of his body, he was described as a lunatic.
In his past, he was tortured with meeting the expectations of his servant mother to gain recognition of his father. He was then sent to Jin Clan to learn cultivation, but was cast out after harassing Jin Guangyao, as he is a cut-sleeve (homosexual). He returned to Mo Village and his mother died soon after, leaving him in the care of his abusive aunt, Madam Mo, and her son, Mo Ziyuan. Both were resentful of his wasted opportunity at becoming a cultivator of a prolific clan, and hence physically beaten and verbally abused him to the point of insanity.