RinYukiShi

RinYukiShi is the poly ship between Rin Okumura, Yukio Okumura and Shiemi Moriyama from the Blue Exorcist fandom.

Canon
Because Rin and Yukios' guardian, Shiro Fujimoto, kept Rin out of the world exorcists and demons, but did allow Yukio to enter it when he was young, he became the first Okumura brother that Shiemi met when they were both young. Around the time Yukio just became an exorcist and was finally allowed to go in the supply shop, that Shiemi's family runs, for the first time. As Yukio and Shiro were leaving the shop, Shiemi works up the courage to walk up to Yukio so she can give him a four-leaf clover, and after Yukio thanks he and tells Shiemi that she doesn't have to call him "teacher", she gives him the nickname "Yuki". While Rin continues to leave a normal life outside the exorcist world that Yukio kept its existence from his older twin, which includes Shiemi's existence as well, Yukio made time to talk with Shimei in passing whenever he goes to her family's shop which allowed Shiemi to develop a little crush on Yukio. During one of their conversations, Yukio tells Shiemi that he has a older twin brother.

Sometime after Rin finally learned that demons exist and that Yukio is an exorcist like their guardian was, and wanted to become one as well so he could make their biological father, Satan, pay for what he did to Shiro, Rin begins to attend Cram School where Yukio turns out to be one of his teachers. When Rin meets Shimei for the first time, he learns that Yukio is making a trip to the supply shop and asked his younger twin brother to take him alone. Because Rin has just started out as a page he wasn't allowed in the shop and as he wonders the grounds, waiting for Yukio's return, he spots Shiemi through the garden's anti-demon gate that burns Rin the moment he touched it. Due to how the just damaged gate reacted to Rin, Shiemi became frightened of him as she began to think that he is a demon, which angers Rin when he heard her call him one; but after Rin learns that Shiemi is having trouble with her legs he offers to help her fix the gate. Moments before Rin began to help Shiemi repair the gate, and after Yukio got the items he came for he asks Shimei's mother about how she has been doing before her mother asks Yukio for help with Shiemi's legs, since she is worried that a demon is involved. After Shimei learns that Rin isn't a bad person or demon, she begins to talk to him about the Garden of Amahara and hoe her garden once belonged to her late grandmother, before Yukio discovers them together and was angry that Rin is on the shop's grounds even he had told him to wait outside.

Rin was surprise to learn that Yukio and Shiemi know each other and didn't like how they were both ignoring him as they spoke to one another. Shiemi was also surprized by the fact that Rin is Yukio's older brother, since Yukio's acts more mature that Rin. despite Yukio being upset wit Rin, he allows him to stay as he examines Shiemi's where both brothers see root-like marks on them, that are from a demon stealing energy from them. After Shimei yells at her mother and collapses, the brothers help her mother bring Shimei to the shed that Shiemi moved into after her grandmother passed away, and as they were leaving the shed her mother tells the brothers how obsessed Shiemi has been with the garden when her grandmother died. Hearing this, Rin goes back to wait for Shimei to wait up so he could talk to her, before Yukio noticed that Rin is gone and when he caught up to his brother, he kept his presence hidden from the two of them since Rin's actions and words to Shimei got her to open how her feelings about how she blames herself for what happened to her grandmother, along with Rin saying that he would carry Shimei to the Garden of Amahara if her legs continue to fail her. Not long after Yukio made his presence known to the two and tells Shiemi that he is now able to exorcise the demon from her, the said demon wasn't planning on letting Shiemi go and began to use her as a human shield against the brothers. Rin tries to fight the demon with his sword, without a plan while Yukio works on coming up with one, since the demon kept facing Shiemi's unconscious body in their direction to keep both of them at bay. When Yukio stated that he is going to shoot Shimei in order to shoot the demon, Rin became worried for Shimei's like and that his brother had lost it. In the end, the bullet turned out to be harmless to Shiemi and Yukio had used it to separate the demon from her, so Rin can take it out with his sword.

Yukio catches Shiemi in his arms as she regains conciseness while Rin stands by and sees Yukio acting like Shiemi's prince charming, before the brothers help Shimei to stand on her own two legs again. Rin gets Shiemi to makes things right with her mother, before he asks Yukio what was in the bullet he earlier used as Yukio tells Rin that is he every goes off the deep end, he knows that his brother will be able to pull him out of it. After talking to Yukio, Shimei becomes Yukio's newest student and Rin's classmate, as she was inspired by both of them to join Cram School so she can become strong like Rin and get the chance to see Yukio teach up close.

Fanon
Because fans commonly rival RinShi with YukiShi, since Shiemi has shown signs of liking both Okumura Brothers and vice-versa with them liking her, the poly ship between the three serves as a peaceful alternative.

Fandom
FAN FICTION
 * Rin/Yukio/Shiemi tag on FanFiction.net
 * Rin/Yukio/Shiemi tag on FanFiction.net