Xiao Xingchen was one of Baoshan Sanren's disciples who left the mountain for the mortal world. Xiao Xingchen has a soft personality but a solid heart, gentle on the outside but determined on the inside. The cultivation world describes Xiao Xingchen as the "bright moon and gentle breeze," paired with Song Lan's the "distant snow and cold frost." He enters cultivation society to help save the world.
He is initially sympathetic to Xue Yang's delinquent ways due to his youth, demonstrating his kind heart. Yet he is also intelligent, aware of Jin Guangyao's use of flattery to smooth tense situations.
After the slaughter of the Yueyang Chang Clan, the cultivation world could not find any evidence pointing towards a culprit. Xiao Xingchen volunteers to lead the investigation, and within a month, he identifies Xue Yang as the murderer. He chases Xue Yang across three provinces before finally apprehending him. Xiao Xingchen brings Xue Yang to a Discussion Conference hosted by the Lanling Jin Clan. He demands severe punishment, to the agreement of every clan save Lanling Jin itself. Unbeknownst to everyone else, Jin Guangshan desired the power of Demonic Cultivation, and Xue Yang was the only disciple who showed any talent for it, as he was able to form a replica of the Stygian Tiger Seal. Xiao Xingchen continues to insist on punishment, until Nie Mingjue catches word. The hot-tempered leader of the Qinghe Nie Clan supports Xiao Xingchen, even unsheathing Baxia to kill Xue Yang on the spot. Jin Guangshan finally acquiesces to put Xue Yang to death. Throughout his trial, even when Nie Mingjue's saber pressed against his throat, Xue Yang continues to grin. He taunts Xiao Xingchen not to forget him.
Despite his word at the discussion conference, Jin Guangshan swiftly commuts Xue Yang's sentence to life imprisonment instead of death. From there, the Lanling Jin Clan begins to pressure the surviving members of the Yueyang Chang Clan, including their young leader, Chang Ping, to recant their testimonies. Chang Ping eventually caves. When Xiao Xingchen attempts to speak with him, Chang Ping pleads with Xiao Xingchen to drop the matter. Thus, Xue Yang is freed.
Xue Yang wastes little time enacting vengeance upon Xiao Xingchen. Instead of hurting Xiao Xingchen directly, he kills everyone in Song Lan's Baixue Temple and poisons Song Lan's eyes, blinding him. This time, he also leaves no evidence that can convict him of the crime.Xiao Xingchen then breaks his vow to his former teacher, taking Song Lan back to Baoshan Sanren's celestial mountain. He begs his teacher to restore his friend's sight and offers his own eyes as a transplant. She eventually agrees.At some point, Song Lan tells Xiao Xingchen to leave him in a fit of grief. Xiao Xingchen thus heads down the mountain blind and alone, while Song Lan stays another year to fully recover.
Sometime later, Xiao Xingchen meets A-Qing when she pretends to be blind in order to steal from him. Though he reprimands her for stealing, she grows fond of him when he protects her from another man she had pickpocketed. A-Qing suggests that since they were both blind, they should travel together and look out for each other. While traveling to Yi City, Xiao Xingchen and A-Qing come across a badly injured man lying by the side of the road. Xiao Xingchen take the man back to their small coffin house to treat him. However, he is unable to see that the man is actually Xue Yang. Once conscious enough to recognize Xiao Xingchen, Xue Yang disguises his voice to avoid revealing his identity. After declaring that he too is a cultivator, he lives with Xiao Xingchen and A-Qing for a while and participates in night-hunting with Xiao Xingchen. Xue Yang had discovered that Xiao Xingchen's sword Shuanghua recognizes corpse energy but cannot distinguish between Fierce Corpses and living people afflicted with Corpse Poisoning. Xue Yang makes use of this information by cutting out the villagers' tongues so Xiao Xingchen cannot tell apart the living and the dead, thereby deceiving Xiao Xingchen into killing them. A-Qing recognizes the villagers as the ones who had laughed at the trio's disabilities when they went out together previously. While she does not have the cultivation knowledge to discern the truth, she remains vigilant. One night during the winter, A-Qing demands to hear stories. Xiao Xingchen tells her about Baoshan Sanren's celestial mountain and the cultivators who left her mountain. When Xue Yang asks about his own travels, Xiao Xingchen mentions a very good friend of his whose whereabouts he no longer knows. Xue Yang then offers to tell his own story about a child who got beaten up for wanting candy, and both Xiao Xingchen and A-Qing realize the story is from his own past. Xiao Xingchen begins giving both of them a piece of candy every morning thereafter.
When Song Lan arrives in Yi City to find his friend, A-Qing quickly determines that he meant no ill intent towards Xiao Xingchen and brings him to their home. However, Song Lan immediately recognizes Xue Yang and chooses to confront him instead of approaching Xiao Xingchen. Xiao Xingchen appears during their fight, led by Shuanghua's detection of corpse energy. Not knowing that Song Lan is covered in corpse powder and has lost his tongue, Xiao Xingchen mistakes his friend for a fierce corpse. He pierces Song Lan's chest, thinking that he is aiding his friend and housemate. Unbeknownst to both Xiao Xingchen and Xue Yang, A-Qing witnesses all of this. The next day, A-Qing waits until Xue Yang departs for the market before informing Xiao Xingchen that their housemate is a man named Xue Yang. Reluctant to break her friend's heart, she lies about Song Lan's death, instead claiming that she has seen Xue Yang kill a young woman. While A-Qing tries to convince Xiao Xingchen to run away with her, Xiao Xingchen becomes so distressed that his gouged-out eyes begin bleeding for the first time in a long while.
When Xue Yang returns, Xiao Xingchen orders A-Qing to run while he confronts Xue Yang, stabbing him and asking if it was "fun" to deceive him. Xue Yang replies that it was and that perhaps he stayed because he was bored. He proceeds to tell the rest of his story about the child beaten for candy, revealing that Chang Ci'an was the assailant who had cruelly abused him as a child. Xiao Xingchen maintains that Xue Yang's vengeance against the Yueyang Chang Clan was disproportionate to the loss of one finger. When he mentions Xue Yang's crimes against Song Lan and Baixue Temple, Xue Yang retorts by asking Xiao Xingchen why he had to interfere with other's business when he failed to see the full picture. Xiao Xingchen cannot bear it any longer and calls Xue Yang "disgusting." It is only at that word that Xue Yang's killing intent appears for the first time in a long while. Xue Yang laughs bitterly and asks if Xiao Xingchen was in a position to be disgusted by him. He proceeds to reveal to Xiao Xingchen how he had tricked him into slaughtering villagers. Xiao Xingchen remains in denial, telling Xue Yang to be quiet. Suddenly, Song Lan appears as a fierce corpse to protect Xue Yang. Once their blades cross, Xiao Xingchen recognizes Fuxue and his friend. In agony, Xiao Xingchen begs for someone to say something. Xue Yang then reveals that Song Lan was the fierce corpse that Xiao Xingchen had killed the previous day. In despair, Xiao Xingchen kneels by Song Lan and slits his own throat with Shuanghua. His actions shock Xue Yang, but believing that he can revive Xiao Xingchen, Xue Yang cleans and redresses his body and even tidies up their house. He then attempts to revive Xiao Xingchen as a fierce corpse, but fails because he had shattered his soul when he died. Xue Yang then collects the fragments of Xiao Xingchen's soul in a Spirit-Trapping Bag and keeps it with him for many years, until Wei Wuxian and Lan Wangji arrived in Yi City. After Wei Wuxian uses Empathy to uncover what A-Qing's Ghost has witnessed, he confronts Xue Yang on the fact that he regrets Xiao Xingchen's death. Xue Yang denies it up until the end, when his hand is revealed to still clutch the last piece of candy Xiao Xingchen had given him, even though it had long since rotted. Once Song Lan is freed from Xue Yang's control, his sentient fierce corpse accepts the spirit-trapping bags containing the remains of both Xiao Xingchen's and A-Qing's souls. He declares his intention to roam the world nursing their souls back to health. Whenever Xiao Xingchen's soul is restored, the first things Song Lan plans to say are "I'm sorry" and "it was not your fault." (Source: Mo Dao Zu Shi Wiki)
