Big Brother Fen... Even though everyone is afraid of you, I have always known that you are not a villain who revels in the slaughter of the innocents. You actually have an extremely kind heart… and you are an extremely good person. You not only saved me, but you also saved all of the people within Floating Cloud City. But why can’t you put down all of your hatred and spare yourself as well! You are always burdened by vengeance and hate, don’t you feel tired?! Doesn’t it hurt?!”— Xiao Lingxi's view of Fen Juechen 
Xiao Lingxi is the the daughter of Xiao Lie and the adoptive aunt of Yun Che. Yun Che's nickname for her is Little Aunt. She was very close to Yun Che, she worked hard in her cultivation so she could get strong enough to protect Yun Che when he had crippled Profound Veins.
Xiao Lingxi has a very happy and bright personality and can be quite dense on some matters as seen when she tried to get Fen Juechen to not kill Yun Che even after all of his protest she never stopped trying.
Later after Yun Che supposedly died in the Primordial Profound Ark her personality became more melancholic and repressed as seen when normally she would laugh loudly or cry loudly in front of Yun Che but when they met again she was trying to repress her crying. 
Growing up in the Xiao Clan Xiao Lingxi used to live in the same courtyard that Yun Che until the time that Yun Che was ten years and her father, Xiao Lie made her move to another courtyard. This caused Xiao Lingxi to cry for days while Yun Che protested, but to no avail. 
Even though they stayed in different courtyards Xiao Lingxi would still sneak to Yun Che's courtyard to sleep with him and afterward get scolded by Xiao Lie, until they learned that it was improper for men and women to be that intimate. 
She and Yun Che had romantic feelings for each other due to being together all the time since childhood. She even made Yun Che promise her to spend the same amount of time with her even after he got married to Xia Qingyue.
On the night of Yun Che and Xia Qingyue's wedding, Yun Che found her at the peak of the forest behind his courtyard where he and Xiao Lingxi used to come all the time during their childhood. This was due to the fact that Yun Che and Xia Qingyue's wedding was in name only and they couldn't consummate it. Xiao Lingxi and Yun Che talked there and Yun Che promised to marry her IF she wasn't his aunt. Yun Che then embraced her and groped her from behind, until they both fell asleep in each other's embrace.
During Xiao Kuangyun's visit to the Xiao Clan, Xiao Yulong told him about Xiao Lingxi, who was extremely beautiful, and hatched a plan to frame her so that Xiao Kuangyun could have his way with her. He did this to curry favor with Xiao Kuangyun and be chosen to return back to the Xiao Sect with him. Their plan to frame Xiao Lingxi of robbery was flopped by Yun Che; however, she was still forced to be locked in the back mountains for 15 years. Xiao Lie managed to get himself locked with her to protect her.
Due to Yun Che's enmity with the Burning Heaven Clan, she, along with Xiao Lie, was captured by Fen Juechen, due to the provocation of Fen Juecheng, and taken to the Burning Heaven Clan as bait to lure Yun Che. Fen Juecheng attempted to rape her but was stopped by Fen Juechen who seemed to have no thoughts to use her for anything other than bait showing that he does have some bottom line and isn't a complete degenerate like Fen Juecheng.
After Yun Che used the Dragon Soul Domain and destroyed the Nine Profound Dipper Formation, Fen Juecheng attempted to use Xiao Lingxi to force Yun Che to stop. However, he was stopped by Fen Juechen, who once again showed that he isn't a complete degenerate.
Xiao Lingxi decided that she would rather die than be used to harm Yun Che and jumped from the window of her prison cell, which was above 200 meters in height and could cause her death due to her minuscule early stage Nascent Profound Realm cultivation. However, Yun Che noticed her and saved her.
- She was born one year after Xiao Yun, making her 21 years old.
- Xiao Lie seems old enough to be her grandfather due to his aging caused by grief.