Spy x Family certainly has its fair share of quirky characters, from the adorably over-expressive Anya to the silent-but-deadly Yor. Out of the supporting characters, one of the most interesting of the bunch is Yuri Briar.
His overbearing attachment to his sister Yor is probably his most memorable and odd character trait thus far, with some fans even questioning his relationship with her. Beyond this, Yuri is an interesting character who will prove to be a spanner in the works for the Forgers. His position at the State Security Service will make sure of it.
A Difficult Childhood
Yor and Yuri's parents passed away when they were quite young. As orphaned children, they could hardly scrape together money to buy books for school. Desperate times called for desperate measures, and Yor picked up a job that could keep her brother in school; unbeknownst to Yuri, this was the start of Yor's career as an assassin. Yor would come home late, sometimes covered in blood, but she quickly brushed the topic aside, for she was able to afford Yuri's school necessities.
Yor would spoil Yuri with snacks and books that she is now able to buy, which Yuri remembers fondly. He recalls her "working herself bloody" (quite literally) for his sake. As his only blood relative, Yuri became fiercely protective over his doting sister. He strived to become a successful man to protect her for the rest of his life, the same way she has protected him for many years.
Yuri's Job
Yuri works for the State Security Service (otherwise referred to as the "SSS"), the nation's tenacious counterintelligence agency. He is a member of the secret police as Second Lieutenant, a fact not even his sister knows. His organization is devoted to internal security. Yuri's main role is identify spies and keep tabs on the populace. His job includes grim functions such as wiretapping, threats and torture. The citizens are terrified of the organization, and have dubbed them the "secret police".
Despite his young age, Yuri is remarkable at his job. His own colleagues, who are significantly older than him, attest to this. The boss of the SSS let him join because of his adorable face and puppy-like nature. More importantly, Yuri knows how to get the work done, indiscriminately.
In the anime, we first see Yuri at work when the SSS brought in someone from the financial department at Yor's day job to their HQ, under suspicion of being a spy. The man was beaten for information, which Yuri continued in his own unique way.Yuri's strategy was asking nicely, until the interrogatee wouldn't cooperate. It is then, when Yuri turns to violence like the rest of the SSS.
Yuri knows about an Agent Twilight. He knows that he is a master of disguise and that he is from the West. The order of the country hangs in the balance with Twilight, according to Yuri. Naturally, this makes Twilight a great enemy to the SSS. This thrilling bit of information sets up an intriguing premise for Yuri and Twilight's future ventures, considering how the SSS' greatest enemy is closer than Yuri thinks.
Yuri's Devotion to Yor
Given their tumultuous childhood, Yuri has become incredibly protective over Yor. This is glaringly evident in the episode of the anime where he meets "Loid" for the first time. Yuri wonders why Yor kept her husband a secret for so long, leaving to assume the worst in him. He wonders if the reason for the secrecy is that he is some nobody who isn't worthy of Yor. He goes into the evening with a preconceived idea of Yor's mystery man, which continues throughout the meeting.
Yuri shows up to the Forger home with a big bouquet of roses, an odd choice for a brother to give his sister a huge bunch of the world's most romantic flower. While Yuri puts on a pleasant face for Loid, on the inside he is judging him - hard. Loid isn't the only one Yuri is faking appearances for, as he hasn't told Yor his real profession. He even wonders if he's coming off as hostile because of how riled up the interrogation from her work made him.
It is obvious that Yuri cares deeply about Yor. When Yuri asks her why she kept her marriage from him, her plain answer was simply that she forgot. Horrified, Twilight is shocked that Yuri believed her. Even more so when she tells him that she forgot that she had forgotten to tell him on the phone in the second episode. Yuri clearly will let anything slide with his sister. All reasoning disappears when it comes to Yuri and Yor.
Yuri is also incredibly jealous of Loid. He can't stand the fact that another man has taken his sister's love, for that man used to be him. As Loid puts on the perfect dinner party for him, Yuri gets angry at petty things like when Loid offers food in the middle of their conversation. His questions about their relationship turn into an interrogation, which changes his jealousy to suspicion that something isn't as it seems with this marriage.
Even when he is duped into thinking it's a normal marriage, Yuri is still just as protective over Yor as he always has. He wants Yor's husband to take care of her the same way he has all these years. Yuri is someone who cares about family deeply, and anyone who threatens that notion is not in his good books. The SSS agent in him is wary of the circumstances, but as a brother, all he wants is happiness for his sister, despite his deeply-rooted sister complex.