Xi Tai (希太, Xī tài) is a Demon King whose return is awaited by the Followers of Set. His current incarnation went by the persona "Mu Jing Ren" (闵星岩, Mǐn xīng yán) until the original persona took over.
When he is introduced as Mu Jing Ren, he is dressed as a student. His face is covered in deep scars that left him as "ugly" in the eyes of his fellow classmates. He has short black hair and blue eyes.
In the past he had long black hair, the ends of which were coloured black and wore dark attire in contrast to Osiris' lighter attire. He also had long pointy ears like Osiris had and Isis currently has. He also had horns on his head.
In present day, Xi Tai often appears with Vampire familiars surrounding him. His hair is allowed to grow long again though he mostly has Mu Jing Ren's hairstyle and only strands of hair are long. He often wears a black cape that covers much of his body.
Xi Tai is described as being as two minds fighting over one soul.
As Mu Jing Ren, he was a kind and gently boy. He had a strong will and fought with Xi Tai for a long time over control of the body they inhabit, though eventually lost and supposedly "died", allowing the Xi Tai persona to fully take over in his stead. Still he knew what he was becoming was bad and had even attempted to halt his cursed fate all along the way.
Xi Tai, in his natural form, is the stronger persona and eventually wins control over their shared soul and body for this reason. Deceitful and cruel, Xi Tai is very much the polar opposite of Mu Jing Ren. However, since mortals do feel such things, as the storyline progresses, Xi Tai begins to wonder if Mu Jing Ren is truly dead after doing several things he couldn't explain why he had done.
Due to his status of being on par with deities, the concept of Sin and Venture, ideals valued by mortals, are foreign concepts to him as they are to others like Isis. As such, he does not feel true emotion at all like a mortal does.
One such example of this appeared later on in the storyline when he is discussing how to become stronger. During his time trying to force Yue Jian to do stuff against her will he speaks about the consumption of food and even the Vampires lust for blood. He notes that everything is designed to eat something else in order to survive, from the consumption of plants to animals. To draw a line on what can and can't be eaten therefore is seen by him as a form of hypocrisy, one aimed souly to make oneself feel better then they are and to make them seem like they have a moral highground. Who gets to eat is something decided by strength, therefore who eats whom is a example of a show of strength to him.
Mu Jin Ren took a liking to Yue Jian over the course of their time together at school. He acknowledge that he came into the world hastily and that destiny was against him. He learnt to care for Yue Jian as she showed him great kindness that others did not and she was with his thoughts for a long time. This built up a desire within him to protect her and everything that made her happy, to lead a normal life where they go to school everyday.
Xi Tai, however, has a very different relationship with her. He heals Yue Jian only to keep her alive long enough for Isis to get her body and has no pleasure in healing her. He has patience, he believes fate will turn in his favour eventually and knows that mortals have their limits. For this reason, he sees little in Yue Jian and was more annoyed by her insistence that Mu jing Ren still lives then he cares for her existence at all. And if not for her purpose in regards to Isis, he would likely have had little interest in her at all, he finds no pleasure in healing her wounds or dealing with her stubbornness at all. In the end he results in tricking her using he relationship with Mu Jin Ren by pretending to be him to get his way and confesses to Isis he only took her out of the two girls because of how close she was to him as him.
Xi Tai has long disdain for his rival Osiris, due to their past interactions. This originally caused him to depart from the world, having lost the will to continue on in his current state.
He is in a mutual relationship with her on a business level, though it is clear the pair are also interested in each other on a deeper level also.
As Mu Jing Ren, he spent most of his time asleep in the class, as he stated he just felt sleep take over him and that he slept throughout nights and mornings. He stated the Primrose bracelet he gave Yue Jian was crafted by himself after he learnt how to make jewelry from a jewelry shop next to his home. He also knew answers to questions in class despite never being awake to listen to the tutor.
Unknown to everyone, he was really the powerful Demon King Xi Tai and is regarded as the Vampire's King. Xi Tai can create 'Sacrificial Lambs', Vampires who are blood thirsty demons in order to find and gather blood for himself. He then either controls or kills them in order to gain access to their blood to grow stronger.
However, the blood alone does not make him as powerful as he should be. Access to Xi Tai's true power, of which he desires, was split among the Demon Clan Bloodlines hidden in the Forbidden Sphere and accessible only the Sacred Weapon of the Lasombra Clan, Xiong Shi. When he finally manages to get to the Forbidden Sphere, he recovers only 3/5 of his overall power with Fan Le Lao taking the rest. Even without his full power, he is more powerful then any Vampire. At full power, his strength makes him on par with deities.
He is shown to be able to control Xue Yan infected individuals and has healing powers. He also grew wings at one point. He has access to many ways of healing people, including Mu Jing Ren's own body.
The Duel with a GodEdit
In the distant past he fought the Egyptian God of the Underworld Osiris. The fight ended with most of his powers sealed away in a sphere of Vampire bloodlines. With most of his powers gone, he still schemed revenge against the God, but eventually lost his spirit and fall into a eternal slumber. It was foretold he would be reborn first as a human and eventually regain his strength.
The disappearance of Mu Jin RenEdit
Prior to her attending, however, he had a strange relationship with Ge Chen. One day while relaxing Mu Jing Ren was sat at the tree drinking next to Ge Chen without him realizing it. He falls asleep and then falls over when asked why he was there. Ge Chen falls asleep next to him, when he awakes a cartoon of juice is left by Mu Jing Ren.
Later when the class try to at a dig at Mu Jing Ren for sleeping while Ge Chen was talking again, he ignores him and continues to help the teacher with the test. When Ge Chen collects the papers at the end, to his surprise Mu Jing Ren answered all the questions right despite sleeping throughout.
He was seen firstly after Yue Jian attends the school when she was forced to sit next to him by Wu Sha as a way of further embarrassing her due to Yue Jian's bandages. It is explained he spends most of the time asleep anyway.
He is seen walking away from the scene of a Vampire attack a few days later by her. . Suspecting the Vampire was him, she attempts to follow him when she sees him leaving the school grounds. She looses him because of 3 bullies, but finds out he took a cat into a Pet Hospital.
A week later she finds hi with the cat, which he had dubbed "Xiao Black". Unable to take care of him, and the cat taking Mu Jing Ren as its master, Yue Rin asks to look after him instead. Later, with a different outlook on him, Yue Jian helps him when he is pressed for an answer to a question by a teacher.
Prior to the discovery of An Chou's death, Yue Jian receive a text on where to find her body. Although the text came from his phone, he stated he lost it. After Zhen Mi is discovered to have been the Vampire behind the recent deaths, he is questioned over why she had his phone and why he did not report it was lost to the school. When he returns to class, the boys in his class decide he may be a Vampire and attack him later. Yue Jian stops them and pushes the 3 boys away.
For looking after Xiao Black, he gives her a Bracelet with a Primrose on it. Later Xiao Black escapes her room after it is ransacked. He is not worried about the cats disappearance as he is a wild cat.
One day they are late for class and Yue Jian asks if he is going to the Summer Ball. he desires to go to the ball so he can be next to her. He leans on her shoulder and she understands it to be another case of him falling asleep on her, but he is happy she took it as that.
Later after school he takes her to a secret Cherry tree full of blossoms and tells him a tale about it. Later, he tells Jalousie to prepare a suit for him that was white, believing it the only pure colour for her despite how dirty he was himself. 
He meets up with Yue Jian at the KaiLun Summer ball. She finds a quiet area outside of the mansion. She asks him if its fine to be out at night, he says its fine but he can't be out past midnight. The pair then dance. During the dance he asks her to fulfill one desire; to remember the kind boy that was Mu Jing Ren. She agrees.
Suddenly at midnight he falls on his knees as Xi Tai starts to move. Ge Chen appears and notes the raise of Xi Tai is ahead of schedule and that he can not longer be controlled. He begs hi to take Yue Jian away to not see this side of him. When Ge Chen goes to kill him, Xiao Black protects Mu Jing Ren.
The next day he vanishes when Yue Jian returns to where the pair were dancing, she finds the scenery is in a state of disrepair and a group of workers are clearing it up.
A few days past, Yue Jian hears her classmates state he was submitted into Hu Kang hospital after attempting to jump to his death. At the hospital she finds he was indeed admitted but transferred to yet another hospital.
The Followers of SetEdit
He is discovered by Yue Jian asleep when Ge Chen's group invade the HQ of the Followers of Set. While she is happy to have found him, when the group catches up to her, Ge Chen denies knowing who he is and they leave.
After she departs, he wakes up and comments on having a dream on her again.
The Forbidden SphereEdit
Inside the HQ of the followers of Set, Mu Jing Ren fights for control of his shared body with Xi Tai. Xi Tai constantly whispers gentle words to him with dark intentions. He remembers his time with Yue Jian. He screams in agony, as he has done for days as he tries to resist Xi Tai to the bitter end. The High Priest suspects someone has changed him, but his resistance will only lead to torture both mentally and physically for him. Mu Jing Ren states he has a dream of Yue Jian every night where he is bound in chains and she comes to free him.
Inside their shared head, he is confronted by Xi Tai who states that it is foolish to keep up this act. Xi Tai has lost all patience with him and tries to strike a deal. He rejects Xi Tai's deal and attempts to commit suicide.
Jalousie prevents the suicide and Mu Jing Ren, Xi Tai mocks his attempt to protect Yue Jian. He tells Mu Jing Ren even if he had succeeded, he would only heal his body. He hugs mu Jing Ren and he dies telling him he will hug on his behalf, Mu Jing Ren realises, however, to his horror as he disappear what danger she is in. After Mu Jing Ren dies, Xi Tai cries for the loss of this side of him.
Now in control of the body, he turns his attention to Jalousie and tells her it is time for her to complete her last valuable act for him. He then sucks her blood dry, killing her in the process. He realises that no matter how much blood he drinks he cannot ever regain his powers and turns to focus on Osiris and Isis and realises he must to go the Forbidden Sphere to get his powers back.
At the Forbidden Sphere, the Sabbat and Camarilla fight it out for his power. A loud explosion catches their attention, they turn to see Xi Tai himself has appeared to reclaim his power. Mei Lilla tries to warn Ge Chen as Xi Tai strikes him and Fan Le Lao watches as Ge Chen attempts to teleport him away.
As the fight continues the next stage of the unlock occurs and he is attacked by Mei Lilla. She tries to inject into him the contants of the Poison Bottle she has swallowed but he strikes her away to the horror of Ge Chen, Fraser and Yue Jian. He surrounds her in evil spirits that slowly strike at her and gives them a choice of giving up his power or saving her.
Yue Jian rushes forward with her sisters weapon to attack him. She demands he give her back Mu Jing Ren.
When the power is finally released, Xi Tai stands close enough to retrieve his power and is awarded 3/5 of it. He turns to Fan Le Lao, who stood close enough to receive the other 2/5. When Fan Le Lao asks if he is up for fighting, Xi Tai decides it is not worth continuing and draws his attention to Yue Jian. Ge Chen tries to stop him, Xi Tai states the fact he saved her life instead of trying to gain his power and has lost the battle. He takes her as a helpless Ge Chen is unable to do anything to prevent it.
Xi Tai's prisonerEdit
A few weeks after the battle at the Forbidden Sphere, Isis appears physically before Xi Tai. She asks him if he brought 'that girl' to which he gleefully replies that she is being held in the dungeon. She then worriedly asks him to hurry up and added that she will not be able to keep up for too long. Xi Tai caresses her and affectionately tells her not to worry and promises that he will not let anything happen to her.
When she awakens several weeks later she is greeted by Xi Tai who she at first mistakes for Mu Jing Ren. He then introduces her formally to Isis who spoke to her when she entered the Ice Coffin. Yue Jian demands to know her fate, though only get a confirmation they have no plans to kill her. Xi Tai then explains Ge Chen likely found out everything from Corpse Hand on Mu Jing Ren's fate, but protected her by not telling her. He explains that her only use right now of Mei Yue Yin is as a power up, which is Xi Tai's only current interest in her and she does not know how to use it fully.
Then, much to his annoyance she begins to call for Mu Jing Ren. He releases her then hugs her. He bares his fangs and loud laughter fills the air as Isis watches him.
Yue Jian awakens to come face to face with a cage of creatures. She reconigises Wu Sha among them as they reach out trying to get her flesh. Xi Tai is surprised to see she remembers the classmates of her old school and explains they were transformed by the power of the Rotting Bracelet into creatures who only crave flesh and blood, making them less then Vampires.
He explains she is too weak and must consume their flesh to become strong enough to hold Isis. When she refuses to eat them, he tosses her to the creatures to be devoured.
Just before death, he apparently saves her so he can repeat this again when she recovers.
Yue Jian continues fighting. She finally collapses and is healed by Xi Tai, she tries to appeal to Mu Jing Ren again, but he insists it won't work. He states if she co-operates when Isis has her body he will consider sparing her friends.
Yue Jian FallsEdit
As time passes by, Isis is frustrated and confused by Yue Jian's stubbornness as her wounds are taking longer to heal, they discuss things as she sleeps. She speaks out about how she feels about her clones and question why Xi Tai didn't grab both girls and instead grabs only one.
When she wakes up, she sees Mu Jing Ren for the first time in a long time. She is glad to see him having defeated Xi Tai, but he refuses to run away as he explains Xi Tai is still alive. He questions her abilities towards the future. He takes her somewhere and tells her to face the truth.
As Mu Jing Ren, he attempts to force Yue Jian to consumed the flesh of the creatures and makes her weapon go from her hand. She continues to protest and sees through his trick. He then lectures her on his views of food and why she must eat, while mocking her moral and righteous highground she has taken to defend herself as a form of hypocrisy.
It is revealed Yue Jian had given up and feasted on the creatures' blood, by this point she had also stopped resisting it at completely. This pleases him.
- He is most likely based on the character of Set from Vampire: The Masquerade, owed to him sharing a number of storylines from the VtM franchise from the character.
- One of the concepts of the VtM franchise was controlling "the beast" that lies within every Vampire waiting to come out at a moments notice. This concept was also raises when Xi Tai was trying to take over their body.
- Mu Jing Ren gives Yue Jian a bracelet with a Primrose on it. The flower itself represents "love" and was even the symbol of Freya, the goddess of love in Norse mythology.
- In Chinese, both he and the clan who follow him have identical ways of spelling their names.
|Followers of Set|
|misc. characters||Zhen Mi ● Jalousie ● Isis|
|Sacred Weapons||Rotting Bracelet|
|Misc.||Xue Yan ● Sacrificial Lamb|