Yuri Briar/Relationships

Yor Forger
After both of their parents died at an early age, Yor was the one who raised Yuri during his childhood despite living in poverty. Because of this, he has developed a sister complex and will do anything to keep Yor safe, to the point of suspecting her husband of being an enemy spy. In addition, Yuri is very possessive of his sister, always wanting to spend time with her at every opportunity and getting irritated when someone else is around, usually Loid and Anya. He holds a deep appreciation for Yor, as seeing her work bloody all for his sake in their youth motivated him to become a successful man, and he vowed to protect his last living relative.

He is unaware of Yor's secret job as an assassin. Likewise, he hides his job as a Secret Police officer from her, telling her that he works as a diplomat for the Foreign Ministry of Affairs.

Loid Forger
Yuri and Loid have a very complicated relationship, as Yuri is jealous of Loid for being his sister's husband without being told, so he tends to act rudely towards him, even having a one-sided competition with him over Yor's affection. Although he has admitted that Loid is a handsome man with great skills and a good career, Yuri still thinks he is unworthy of being with Yor and would even go to such circumstances to hurt him if he ever found out that Loid harmed or did something bad to his sister.

While he has baselessly suspected him as a spy, Yuri is unaware of Loid's true identity as "Twilight."

Anya Forger
Yuri first meets Anya in person when Yor calls him over to tutor the girl for her midterm exams. Neither of them has a good impression of the other due to Yuri's dislike of Loid and his child, while Anya gets creeped out by Yuri's overly obsessive thoughts about his sister. Using Yuri's love for Yor, Anya is able to persuade him into tutoring her seriously, and he eventually shares his motivation for studying when he was younger, teaching her that knowledge is power. Although Yuri later stomps off in frustration when Anya fails to learn anything, the study session makes him realize that he needs more knowledge in order to keep his sister and country safe.

Yuri learns to tolerate her as he, along with Loid and Yor, tell Anya that lying is wrong, despite them all lying about themselves. Later, when he learns that Anya was among the hostages taken by the Red Circus, he rushes over to the Lieutenant with concern to confirm this. He initially obeys orders to not come, but ultimately refuses, knowing that losing the child would break his beloved sister's heart. Yuri helps find the other missing bus in the hopes of saving Anya. While he does not directly save Anya and gets shot in the shoulder, his actions help culminate in Anya's rescue from the bus.

SSS Lieutenant
Yuri's senior in the SSS. He looks out for Yuri and urges him to take care of himself more, telling him to stop drinking and being careful after hearing about him overworking. He keeps Yuri in check to stop him from acting hastily and is aware of his sister complex, which he tells him to grow out of. After Yuri collapses while Yor is on a business trip, the Lieutenant helps him recover. Most times, Yuri will tell him he is fine after getting injured so he can continue working.

During the Eden Academy bus hijackings by the Red Circus, Yuri is ordered by the Lieutenant not to come so as to not complicate the situation if Anya recognizes Yuri. When Yuri insists on going, he is restrained to a pillar by the Lieutenant to keep him at HQ.

SSS Boss
The Boss is the man who scouted and recruited Yuri to the SSS. While the exact reasons are unknown, the Boss says that he did it because he found Yuri "adorable, like a cute little puppy." Yuri appears to be close with the Boss, who has even invited him out for a steak dinner. This has earned Yuri the reputation as the Boss' "pet" among his peers. Yuri does not appear to be bothered by this title, either being unaware or willfully ignorant, and continues his job with enthusiasm, even telling the Boss that he will one day capture Twilight, which the Boss seems to appreciate.

Dominic
Yuri's friend and neighbor working at Berlint City Hall. Occasionally, Yuri has Dominic update him on how his sister is while he is out for work.

Camilla
Camilla had already an idea of what Yuri looked like by photos Yor showed her in their work, but they officially met at Camilla's house when she was teaching Yor how to cook, and Yuri was called to taste test. In the beginning, Yuri thanked Camilla for being there for Yor but got mad at her for being rude towards Yor, even contemplating getting rid of her. He then changed his mind after Camilla angrily claimed that it would be easier for Yor to break up with Loid than to give her cooking lessons.