Yui had always had a knack for playing chess for he'd always used to play the game with his younger half brother Lelouch vi Britannia, but of course, he always lost. However, he was a good sport about it and considered Lelouch to be his rival. Aside from chess, he loved painting, for it was noted by Euphemia that he was a talented artist after she'd discovered a few of his paintings on accident, plus there are some of his portraits displayed in one of the many museums in Britannia. And Yui was definitely a ladies man, hitting on any beautiful woman in sight, whether they were Britannian or Haumean. He mostly spent his time flirting with young Tami Kanon whom he'd renamed Prima by often groping and trying to kiss her for which he'd receive a punch to the face for it. While Yui was once a magic user and was somewhat good at it, he was never quite as good as his twin brother Fai and has on many occasions tried to outdo him in anything, no matter what it was.
Without realizing it, Yui had always been known to run off at the mouth and say things that get him scolded by Fai. The two of them could appear close in front of others but in reality, they were very different from one another. An example of this is Yui not minding to use his title and power as a Britannian Prince to get things done when he wants them done. It may not be the things that should be done in order to help the Haumean people but whatever he said, goes. He won't hesitate to issue an order to have countless Haumeans killed if it meant keeping up appearances in front of others, something that Fai would never do. Aside from being completely different personality wise, they were also different powers wise. While they were both descendents of their mother's kingdom, Valeria, the two of them had inherited her Anodite powers, however, because of their grandfather's actions, they had to be careful and conserve what they had. Yui, being hardheaded, didn't listen and often used his powers to do mischievous things.
Whether it was playing tricks on his older siblings and the guards or trying to outdo Fai who was clearly smarter and stronger than him. He was always envious that his brother was ten times better at doing things than he was and as such, they had a lot of disagreements. But because of his careless overuse of his powers, he lost them at an early age, therefore his eyes (which stored all of his power) change to their natural color which was violet, the same color as their father's eyes. As for his sister younger Anne, he never had a brother-sister relationship with her and referred to her as 'Annie', hating how much of a pain in the as she was. At times he can get very timid and scared easily when back into a corner because he of the simple fact that he is unable to protect himself. What caused his death at the hands of Zero was because he'd stained his hands with the blood of the innocent and for that, he had no pity on him and took his life.
Yui is 6'2 with short blonde hair and blue eyes and is usually seen wearing a long sleeved black and white sweat shirt with a scarf around his neck, beige and black pants and black boots. Since Yui doesn't have any powers, he is not seen carrying any forms of weapons.
Yui La Britannia is the Fifth Prince of Britannia with twin brother, Fai La Britannia, carrying the title as Fourth Prince of Britannia and their younger biological sister Anne La Britannia carrying the title as the Seventh Princess of Britannia. All three of them share the same father, obviously, Charles zi Britannia but their mother, Princess Marie La Fluorite however, came from the Valeria Kingdom. There all kinds from spellcasters to priests and priestesses, magical creatures (main magical ‘creatures’ being energy beings known as Anodites) all dwelled under the same kingdom.. The rulers of Valeria, King Wei La Flourite and Tomoyo La Flourite, parents of two children, Marie and her younger sister Annette, did not approve of their daughter conceiving a child with Charles. It was because of his methods of ruling and the fact that Britannia had conquered Haumea and Japan both that they didn't agree with. On top of that, they were steady at war with resistance groups. Marie was at ends with her parents who she felt were trying to run her life when she was old enough to make decisions for herself. She didn't become pregnant with Fai and Yui until she was the age of twenty, against her parents protests of her relationship with Charles. An abortion was out of the question since Marie refused to get one and wanted to have her child, (she thought it was just one at the time), in Britannia. Wei and Tomoyo were deeply against it, to a point where they locked their own daughter away in a tower where her magic would be ineffective. Nine months later, she gave birth to her boys, twins that she'd named Fai and Yui. It was a joyous moment for the princess but entirely the opposite for her family and their kingdom. In Valeria, the birth of twins was considered to be a bad omen. Shortly after their birth, Second Princess Annette died, and their mother committed suicide out of guilt for allowing Fai and Yui to be born. In addition, the kingdom suffered many misfortunes, and the twins, when combined, bore powerful magic that rivaled that of their grandfather.
Wei decided that the only way to break the 'curse' as he called it, he reluctantly sent Marie and her two twin boys away to live in Britannia palace with the other wives and children. Because so much had happened in Valeria, Marie felt that it was her own fault for birthing Yui and Fai but she continued to love them and raise them on her own since Charles was never around. She later married the Emperor at the age of 30 while also being pregnant with their third child, which was a single birth this time around. It was a girl that she named 'Anne' after her sister Annette. Yui and Fai were only fifteen when their little sister was born. And living in the Pendragon was no picnic for them either. The Emperor already had more than one wife and because Marie came from such a powerful kingdom, the others were often jealous of her. Their own children picking and teasing hers, no matter how much she pleaded for them to stop. And to make matters worse, things back in Valeria hadn't gotten easier with her gone. Her father eventually became insane and he executed everyone and then jumped into the valley himself and committed suicide and the kingdom itself fell, becoming dark, desolate and cold. Fai, Yui, and Anne, had no other family outside of Britannia now. Their grandparents died, their aunt died... the only family they knew and had been in Britannia. But the deaths of her entire family drove Marie into a deep depression to where she often tried to harm herself with sharp knives and other various types of sharp objects. As Yui had gotten older, he mainly started doing things he wanted to do. Ignoring his mother, younger sister, and sometimes Fai to do things he knew would get him into trouble.
He wasn't so bad as a child, being a quiet and friendly time that enjoyed playing a game of chess with his older brother Renji and younger half brother Lelouch. He lost to them both ALL the time, whined for a while but considered his brothers both to be good rivals. Mainly Lelouch since Renji was always busy. He had sort of a rivalry going with his own twin brother because, although they both inherited their powers as Anodites from their mother, Yui overused his powers to the point that he eventually became powerless and human, whereas Fai conserved his powers as well as tried to learn how to use them to get and stay stronger. He was better at using his abilities than Yui was, making him often jealous of his brother. It wasn't until much later that Lelouch and his younger sister Nunnally were sent away as hostages to Haumea after the death of Empress Marianne. Charles made it so that they had been killed during one of the many wars and so Yui believed this to be true as well. Fai was the one that kept telling him that they were still alive but there was no proof of their existence anywhere. Yui just brushed it off and Anne didn't make things better by commenting on how she's glad that Nunnally was death because she was tired of the girl's nature of wanting to be nice to the Elevens and treat them with respect. She hoped her half sister burns in hell. Anne also wishes the same for Chikage and any of her other siblings who thinks it's okay to get involved with the Elevens. However, Yui had his own views about how the Elevens should be handled. He felt that instead of disposing of them, capturing them, finding out any talents or strengths that they have and then force them to work for the Imperial Family was much better than just simply killing them all the time. But when necessary, he won't hesitate to issue an order to have them killed to keep up appearances in front of others.
Four years had passed, yet another war broke out between Haumeans and Britannians to where more lives had been lost. Yui and Fai explored the damage and came across a young Haumean girl named Tami Kanon who the twins found to be absolutely adorable. Instead of having her executed, they Fai had her wounds treated, giving her a place to stay in the palace. Not only that, the girl was famous for her angelic voice and used to sing for the late King and Queen of Haumea, whom their father ordered to be killed to insure they wouldn't try to overthrow Britannia. Haumea had an heir to the throne, which was a daughter that'd been captured by the Emperor and used her as a mere test subject in Geass projects. Tami, on the other hand, it was Yui's idea to rename her 'Prima' even though Fai wanted her to keep her original name. The girl was strong. She'd always fought with if it wasn't them it was other members of the Imperial Family. Discovering that she'd has telekinesis abilities. Fai was the only one that was able to calm her down, shutting her powers within her since Yui was unable to. Anne and Fai are the only ones left with powers now since their mothers homeland is nothing more than a dark and desolate area. It wasn't until Renji had ordered a power canceling bracelet to be placed upon the girl's wrist to stop her from using any other abilities that she had, that'd Yui oftentimes took advantage of certain situations to flirt and/or grope the young Tami who he'd renamed 'Prima', that was forced to sing for Britannians ONLY and no one else. Many times has Yui felt Prima up and each time, she'd punched the hell out of him for it. It's not like he was already known for being a ladies man by many of the Britannian Royals, mainly the women. It didn't matter to him if they were of royalty or an Eleven, if he felt that a woman (or child) was beautiful, he'd make suggestive comments towards them. Not being able to help keep his hands to himself.
Yui decided to become the Viceroy of Area 11, knowing that Lelouch and Nunnally had died there when in fact they were very much alive. His brother became the Sub Viceroy in hopes of bringing some change to the Elevens but even with the titles, they were nothing more than figurehead tools. It wasn't until after several events in the Namaka Ghetto, in Area 11 that from that moment on, chaos had formed, a random attacker (unaware that it's Lelouch disguised as Zero), was helping out the resistance members that were fighting the Britannians.
He was part of a project that involved many experiments and information in regards to a mysterious power known as ‘Geass’. Apparently, a resistance member disguised themselves as a Britannian soldier and obtained what information about it that they could to be able to use and expose the Britannian Royal Family’s secrets of some sort of secret weapon to exterminate Haumeans (or so they believed). Fearful of the information being leaked to the public as well as being disinherited, Yui hid the truth and gave a command to eradicate everyone in the Namaka Ghetto. Eventually the attacker confronted him, the one who also told him to give a 'cease fire' order immediately. It was then he discovered that Lelouch was alive. Shocked even.
He offers to take Lelouch back to the Pendragon Palace for which he refuses, stating to Yui that their father considers all of his children nothing but tools. He takes this opportunity to use his geass power of Yui to find out information about the incident of Empress Marianne vi Britannia’s death. He firsts asks Yui was he the one who killed Marianne which Yui, under the control of the power, tells him he did not. Lelouch then asks did he know of anyone who might know. Yui tells Lelouch that Prince Renji El Britannia and Riku Li Britannia might be able to tell him who killed Marianne. That was all he knew. As the affects of the geass wore off, he came face to face with the barrel of Lelouch's gun. He pleaded for his life and told him that he swore he didn't know anything about Marianne's death nor was he involved in it. Lelouch believed him, but still took his life because his hands were stained with the blood of innocent people. Even at his death, Yui was presented to the public as a person who fought for Britannian security and prosperity.
- Yui hated his sister Anne.
- Because the Valeria Kingdom became a dark and desolate kingdom, there was no longer any remaining power to draw from there, therefore Yui lost his powers due to much over usage of them.
- Yui attempted to force himself onto Tami Kanon.
- Yui's role was basically the same as Clovis's role in the Code Geass series except Clovis did not have a twin nor a slave Eleven.