Fullmetal Alchemist: Brotherhood is a fantasy shonen series with a fascinating cast of characters, from the wandering brothers Edward and Alphonse Elric to the scheming prince Ling Yao to the living Philosopher's Stone, Van Hohenheim. But not every character is a rogue. There's also the matter of Colonel Roy Mustang, an ambitious officer in the Amestris military.
Roy Mustang is noted for three things: his powerful flame-based alchemy, his determination to become the next leader of the country, and his stubborn personality as a career military man. He has earned the respect of many, but many anime characters would find his personality or his ambitions questionable or downright annoying. Who might Roy's detractors be?
10 Naruto Uzumaki Would Butt Heads With Roy Nonstop (Naruto)
It's true that Naruto Uzumaki aspires to become Hokage and thus has a similar goal as Roy Mustang. However, these two shonen characters are rather different people otherwise, including Roy Mustang's willingness to take part in genocide and perpetuate hate and violence.
Naruto would be horrified that Roy didn't object to the Ishval Civil War, and sure enough, Scar is like the Pain of the Fullmetal Alchemist world. Naruto also wouldn't like Roy's strict military rigidness. No one can just order Naruto around like that.
9 Katsuki Bakugo Would See An Annoying Rival In Roy Mustang (My Hero Academia)
Katsuki Bakugo is highly ambitious, just like Roy and Naruto, and he won't let anyone beat him to the top of the hero world. He's determined to become the new #1 hero, but here comes Roy Mustang, acting all cool and confident about becoming the leader of Amestris as a savior and hero of the people.
Bakugo already has enough rivals, and if the two met, Roy would definitely be seen as yet another competitor who's threatening to one-up Bakugo. If that weren't bad enough, Bakugo would be reminded of the fire half of Shoto's Quirk.
8 Raphtalia Would Be Reminded Of Her Race's Many Tragedies (The Rising Of The Shield Hero)
Roy Mustang didn't enjoy the Ishval genocide campaign the way Solf J. Kimblee did, but he also had no serious objections and incinerated countless innocents with his flame alchemy to get the job done. This will make him a monster in the eyes of many anime characters, including the demi-human Raphtalia.
Raphtalia lost many of her friends and fellow villagers to exploitative humans, and she would feel terrible for all the Ishvalans who died at Roy's hands. She also wouldn't like Roy's rigid military ways, preferring to run free as an adventurer.
7 Katara Would See Fire Lord Ozai In Roy's Eyes (Avatar: The Last Airbender)
Katara of the Southern Water Tribe suffered a terrible loss when the Fire Nation attacked. The Southern Raiders killed her mother, and ever since then, Katara has been highly wary of Firebenders and anyone from the Fire Nation.
Katara wants the Fire Nation to go down, but she won't antagonize innocent Fire Nation citizens in the process. Then there's Roy Mustang, who slaughtered Ishvalans with his flames, and Katara would see another Firebender who needs to be punished for their crimes. She wouldn't like Roy's personality, either.
6 Inosuke Would Be Convinced Roy Is Looking Down On Him (Demon Slayer)
Inosuke Hashibira is a feral and wild demon slayer, and he is quick to form rivalries. He's the type who needs to prove himself to anyone, and he does not take kindly to rules or regulations of any kind. He's not the type to fall in line as a soldier.
By contrast, Roy Mustang is a career military man, a self-centered schemer who follows the rules while also using them as a ladder to reach new heights. He'd look down on the likes of Inosuke, and Inosuke would deeply resent him for it. How dare Roy sneer at beast breathing?
5 Tsukasa Shishio Would See His Ideological Enemy In Roy Mustang (Dr. Stone)
Tsukasa Shishio is the world's strongest high schooler, but he's not all muscles and no brain. He is aware of how much business leaders, politicians, and police officers neglect or exploit the people, and he is determined to make a new world free of laws, hierarchies, or oppression.
Thus, Tsukasa would see his worst enemy in Roy Mustang, a scheming adult who will use and deceive people for his own selfish gain. And, of course, Tsukasa would be disgusted by Roy's role in the Ishval Civil War. All people are equal in the eyes of nature, so how can the Amestrians think to destroy the Ishvalans like that?
4 Thorfinn Would Get Sick Of Roy's Ambitions & Schemes (Vinland Saga)
Thorfinn Karlsefni was rather different from his father during his years as a warrior. Unlike the pacifist Thors, who believed that he had no true enemies, Thorfinn defined himself by vengeance and cunning, and he was happy to destroy his enemies if it meant getting a chance to fight Askeladd later.
However, Thorfinn doesn't like being ordered around, and he knows how corrupt and wicked kings and princes can be. He doesn't trust schemers or politicians, such as King Sweyn, and he would sneer at Roy for being yet another schemer who's bound to lose it all when someone else usurps the throne eventually.
3 Annie Leonhart Would Lose Patience With Roy's Constant Plotting (Attack On Titan)
At first, Annie Leonhart appeared to be a loyal warrior fighting for Marley, but in reality, she only cares for her adoptive Eldian father and is being obedient for his sake. Annie doesn't care that much whether the Marley Empire wins this war or not, and she isn't terribly loyal to the Scouts, either.
Instead, Annie rejects all armies, governments, and causes, and she is sick of war and politics as a whole. No matter who wins, her life won't be any better, and so, Annie would quickly get tired of Roy Mustang's schemes and ambitions. It's a fool's game, Annie would argue, and Roy is wasting everyone's time. Can't he just live a quiet, normal life instead?
2 Ichigo Kurosaki & Roy Mustang Would Not Be Compatible Allies (Bleach)
Ichigo Kurosaki wouldn't exactly hate Roy Mustang's guts, but he would also struggle to get along with him. Ichigo is a stubborn and independent-minded fighter who does things his own way, rather than integrate himself into a chain of command. He's no soldier, and that sets him apart from Roy.
If they ever met during a battle, Roy would try to order Ichigo around and get annoyed when Ichigo refused to obey. Ichigo wouldn't like Roy's cocky, "I'm in control" attitude, and he'd have no interest in Roy's ambitions, either. Ichigo isn't terribly fond of schemers or plotters, friend or foe.
1 Luffy Would Find Roy's Methods Distasteful (One Piece)
Monkey D. Luffy is in the same league as Naruto Uzumaki and Ichigo Kurosaki in that he is a loyal and friendly shonen hero who wants to save the day on his own terms. He wants to run wild and follow his instincts, all while pursuing his dream to become the pirate king.
Luffy is the last person to become an officer or a bureaucrat, and he wouldn't like Roy Mustang's stern, aloof personality and by-the-book methods for becoming the next leader of Amestris. Roy's fire would remind Luffy of Ace's own powers, but that's not enough to make Luffy like him. And Roy wouldn't like him in return.