Warnings: Spoilers for FMAB, mature language, and a lot of sciency stuff.

¤¤¤

"Alright class, we'll be having a new transfer student joining us for the month," Shota Aizawa stared at his class with a bored expression, and sighed, "you can come in now." The door slid open.

A boy with long blonde hair in a braid came in followed by a much taller person in armor.

"I'm Edward Elric!" The one with braided hair exclaimed, "And I'm your new classmate!" 

"My name is Alphonse!" The boy in armor chirped, "I'm Ed's younger brother!" 

"Hmm… you sound a little young to be here," Momo Yaoyorozu was the first to state the obvious, giving Alphonse a concerned and curious look.

The door opened and another blonde entered, a tall female, in a military uniform. Shorter then the armor, but about the same height as Aizawa. 

"Sorry for the delay," she bowed in apology, "I had to make sure the Colonel was doing his paperwork…" 

"Don't worry about it. Riza Hawkeye, correct? You'll be taking care of Alphonse during class?" Shota turned to her. 

"Lieutenant!" Al sounded happy, turning to the new adult.

"Hey Al," Riza smiled at him, and nodded at the teacher, "yes sir. I'll be watching Alphonse during training." 

"Why the fuck is he wearing armor?" Katsuki Bakugo growled, glaring at them. 

"Kacchan don't be rude…" Izuku Midoriya sighed a little, glancing at his childhood friend. 

"Don't tell me what to fucking do nerd," Katsuki replied. 

The three new people looked at each other, before Al spoke. 

"I-its protection, b-because… I-I'm quirkless…" Al mumbled. 

"HAH?!" The entire class exclaimed at once. Shota sighed. 

"That's enough. Everyone suit up, and head outside, we'll be meeting Mic and another transfer teacher outside for training." Shota said, leaving the classroom. 

It didn't take long for questions to start.

"Where are you from?" 

"We're from Amestris!" 

"What's your quirk!?" 

"It's called Alchemy! Pretty complicated, to be honest. It's easier if I show you during training."

"Lieutenant and Colonel are military terms, are you part of the military, or associated with it?"

"Yes, Edward is a State Alchemist. He's an important member of the military." 

The girls and boys split up to change, while Riza and Alphonse followed Shota outside.

¤¤¤

"Whoa! Nice hero costume Elric!" Mina Ashido cheered, making Edward smile.

"Thanks Ashido! Made it myself!" He grinned. 

"Looks fucking stupid," Katsuki retorted. 

"You wanna fight me wise guy?!" Ed glared up at him, crossing his arms. 

"You're on pipsqueak!" Bakugo smiled menacingly. 

"In that case, you two can go first. Arena is over there." Shota pointed to an empty field. 

"Fighting already Fullmetal?" 

Riza sighed, Al looked at the voice, And Ed groaned. 

"Get lost Colonel Bastard I'm busy!" 

"Whoa there little listener!" Hizashi Yamada exclaimed, leaning on Shota, "That's not a good way to speak to your superiors!" 

"Don't let me stop you," Roy Mustang shrugged, and stepped back. 

"Who are you?" Shoto Todoroki questioned, looking up at him. 

"Colonel Roy Mustang," Roy replied, "I'm here with the Elrics." 

"Shouldn't you be doing paperwork sir?" Riza asked, raising an eyebrow. 

"I finished it…" Roy sweat dropped.

"Uh huh…" Riza sighed, her tone disbelieving, but not pressing the matter. 

"A member of the military? It's a pleasure to meet you," Tenya Iida adjusted his glasses, nodding up at them. 

A loud yell stopped Roy from replying. 

"WHAT THE FUCK?!" Bakugo screeched. 

"Fullmetal, status!" Roy barked loudly, glaring as the smoke cleared. 

"He broke my GODDAMN arm!" Edward yelled back. 

"Bakugo!" Aizawa yelled. 

"I didn't fucking break his arm!" Bakugo yelled back. The two stood glaring at each other, as Roy sighed. Edward's right arm was limp at his side. 

"Not again…" Al sighed.

"What happened to his arm?" Izuku asked. 

"Bakugo must have broken it if it's limp like that," Riza sighed. 

"I knew bringing Winry would be a good idea," Al mumbled. 

Seconds, later there was an angry shout.

Meanwhile…

"So, Rockbell, where' ya from?" Mei Hatsume asked, looking up at the blonde Winry Rockbell, a support course transfer student. 

"I'm from Amestris," Winry replied, "you probably haven't heard of it, it's a pretty small place, surprisingly." 

"Nope, can't say I have. What's your quirk?" Mei questioned, curious to know about the new girl that was helping with her babies. 

"It's called 'Automail Sensor'," Winry explained, "I can find and tell what happens to anything I build out of automail." 

"Automail? What's automail?" Mei asked, giving her a curious look. 

Winry gasped, "You don't know what automail is?!" 

Mei shook her head. 

Before Winry could respond, something snapped inside of her. She recognized that feeling. 

That was the all too familiar, of a certain blonde's arm breaking.

The blonde's expression darkened, as she grabbed a wrench and stormed out of the room. 

"Rockbell? Where are you going?" Mei asked, following her. 

Winry didn't answer, just continued storming outside. When she was out, and was in sight of a certain class, she yelled angrily. 

"EDWARD!"

The person in question, squeaked, his face shifting into one of absolute terror. 

A wrench came flying towards him, and he yelped as it whacked him on the head. The rest of the class was confused, but Al sighed, Riza shook her head, and Roy facepalmed.

"Guess we don't have to look for her." 

"EDWARD ELRIC YOU BROKE YOUR AUTOMAIL AGAIN?!" Winry yelled, running towards him, Mei behind her. 

"WHAT THE HELL WINRY ARE YOU TRYING TO KILL ME?!" Ed yelled back, holding his goose egg from the wrench.

"DON'T TALK BACK TO ME DUMBASS, I'M THE MECHANIC!" Winry retorted, slapping him and pulling up his right sleeve. She nearly burst into tears at the sight if her precious automail. 

"A metal arm?" Shota questioned. 

"Leg too, the young lady is Winry Rockbell, a childhood friend of the Elric's, and Edward's mechanic. He has a habit of breaking his arm in fights… so this isn't the first time it's happened." Roy explained. 

"How'd he get them?" Mina asked. 

"It's a long story… and one I'd rather not share…" Al sighed, looking down at her. 

"Fair enough," Momo nodded before Mina could press the matter. 

Winry continued to yell at Ed, with a confused Hatsume behind her. 

After more painful hours, school was finally over. 

The dekusquad, Izuku Midoriya, Ochaco Uraraka, Tenya Iida, Shoto Todoroki, and Tsuyu Asui, had all decided to come over with them after school. Mei Hatsume had been invited as well, so Winry and her could work together.

"Just don't let them into the repair room or whatever it's called until Winry's done…" Ed sighed. 

"Might just let them watch, then they can see how helpless you are without me," Winry growled, as Ed paled. 

"Calm down you two," Riza sighed, "make yourselves at home while your here." 

They decided to play video games until Ed and Winry were done. 

By the time the two were out, it was dinner and everyone had to leave. 

¤¤¤

The next morning wasn't much different, but everyone was careful to not destroy Ed's arm again. 

"So you can like, make anything out of something?" Izuku asked, taking notes on Ed's quirk. 

"Not exactly…" Ed replied, "it's a little hard to explain." 

"So, how does it work?" Izuku questioned, looking up with confusion.

Edward thought about, before quoting a passage he had once memorized. 

"Humankind cannot gain anything without first giving something in return. To obtain, something of equal value must be lost. That is alchemy's first law of Equivalent Exchange." 

Izuku quickly scribbled that down in his notes. 

"So you turn something into something else of equal matter?" He asked. 

"Yeah, pretty much! Lots of science involved, mostly chemistry, but it depends on the kind of Alchemy. There's a lot of different kinds." Ed nodded. 

"So it's kind of like Yaoyorozu's, but a recycling form…" Izuku started mumbling, confusing Ed. 

"Uh… sure…" he went back to his work. The door burst open suddenly. 

"Ey! Elric! Heard you were in town!" A boy with black hair tied in a ponytail came in. 

"Ling?" Ed asked, standing up. 

"Not this guy…" Roy muttered. 

"Ah, don't be like that Colonel dude! I'm friendly!" Ling Yao exclaimed happily. 

"Who are you and why are you disturbing my class?" Shota demanded. 

"Ling Yao! Friends with this pipsqueak!" Ling ruffled Ed's hair, annoying the blonde. 

Edward punched Ling into the wall angrily. 

"DON'T CALL ME A PIPSQUEAK!" He yelled. 

"B-brother don't punch him!" Al exclaimed.

"Feisty as usual, eh?" Ling stood up, brushing off some dust. 

"Get out, you're disturbing my class," Shota sighed. 

"Ah! Sorry, sorry, I'll be on my way then!" He walked over to the window, and opened it, jumping out. Everyone stared at him, and Roy sighed. 

"Sorry about him, he… tends to follow us everywhere for some reason," Roy sighed, "I'm surprised his lackeys weren't with him…" 

"No they are, I can see them outside." Ed replied, staring out the window, before going back to his desk, "I can't believe that guy… he's such an idiot…" 

"Do you think Mei is here too then?" Alphonse asked. 

"Last I checked she was tagging along with Scar…" Ed sighed. 

"Who are you talking about?" Izuku asked. 

"Just some friends that like to bug us, not a big deal. And Al's girlfriend." 

"S-she's not my girlfriend!" Al exclaimed, a light shade of pink spreading across his armor somehow. 

"Is the armor… blushing?" Momo questioned. 

"Don't ask," Ed shrugged, "even I don't know how that works."

"That's enough, Get back to work everyone." Aizawa ordered. The class quickly went back to their work.

¤¤¤

"Hey, Elric!" Edward paused, and looked behind him. 

"Oh, Yaoyorozu," He turned to her, "can I help you?" 

"I was just talking with Midoriya," she explained, "he mentioned that your quirk is similar to mine." 

"Oh really? Well what's your quirk?" Ed asked, as his friends paused to wait. 

"It's Creation," she replied, "I can turn the atoms in my body into anything abiotic as long as I know the chemical make-up." Ed flinched slightly. 

"Oh… mine is Alchemy, I can turn anything into something of equal matter and value." Ed explained. 

"Even living things?" She questioned. Ed nodded.

"That's a very interesting quirk," Momo noted, "that's all I really wanted to ask about," she smiled, "sorry for bothering you! I'll be on my way!" 

"Yeah, see ya!" He waved as she ran off. 

"Who was that?" Winry asked. 

"Just a classmate," Ed replied, shrugging, "let's go." 

"OI!" Edward groaned as he recognized the voice of his explosive classmate. 

"Bakubro! We just told you, there's no point in picking a fight!" Eijiro Kirishima came running after Katsuki, sighing loudly. 

"Come on man!" Denki Kaminari sighed, following Eijiro. Mina was right behind them. 

"LET'S GO PIPSQUEAK! YOU AND ME RIGHT HERE RIGHT NOW!" Katsuki yelled, storming towards Ed and his friends. 

"DON'T CALL ME SHORT!" Ed yelled, clapping his hands together. Alphonse stopped him before he could transmute anything. 

"Brother! You can't use your quirk outside of class, remember?" The tall suit of armor exclaimed. 

"He's right Bakubro! You can't use your quirk!" Eijiro exclaimed, grabbed Katsuki's arm. Katsuki shoved him away.  

"FUCK OFF SHITTY HAIR! I DON'T NEED MY QUIRK TO BEAT THIS PIPSQUEAK!" He yelled, balling up his fists. 

"STOP CALLING ME A PIPSQUEAK!" Ed yelled, balling up his right arm, and aiming a punch at Katsuki's face. 

Katsuki ducked under it, and punched Ed in the gut, which Edward responded with a kick to the side. 

They continued to exchange blows, until-

"Fullmetal, what is going on here?" Roy demanded, crossing his arms. 

"Get lost Colonel BASTARD!" Ed snapped, "I'm busy!" 

"Edward, that's enough." Riza said, drawing her gun. Ed paled considerably. 

"What the hell?! Is that a real gun?!" Eijiro exclaimed, activating his quirk as his skin hardened. 

"Holy shit she has a gun!" Denki exclaimed. 

"Meep!" Mina hid behind Eijiro. 

"What the fuck?! You're scared of this bitch?!" Katsuki exclaimed. 

"She has a gun bro! Of course we're scared!" Eijiro exclaimed. 

"Okay! Okay!" Ed backed up, holding his hands up in surrender. 

"Oh, for fucks sake," Katsuki ran towards Riza, and attempted to launch and explosion at her. Nothing happened. Within a span of five seconds, Riza put her gun away, and grabbed Katsuki's arm, twisting it to be behind him and with him facing away from her. 

"Agh!" Katsuki yelped. 

"I said, that's enough." Riza said calmly. Everyone was pale, even Roy. 

"Colonel guy, right?! Aren't you her superior?! Do something!" Denki exclaimed. 

"What do you want me to do?!" Roy exclaimed in a panic. Winry facepalmed. She was the only not panicking.

"I don't know! You're the adult here!" Mina squealed, still hiding behind Eijiro. 

Katsuki meanwhile, was looking around. Hos explosion hasn't worked, meaning Shota was here. 

"SENSEI!" He yelled out angrily, getting everyone's attention. 

Shota jumped out of the nearby tree, his hair and capture weapon floating around him. 

"That didn't take long." He muttered, "Elric, Bakugo, I'm disappointed in you both." 

"Sensei! Do something, crazy lady has a gun!" Eijiro exclaimed. Riza sighed, and let go of Bakugo. 

"I'm not crazy. It's part of my job." She said stiffly. 

Everyone sighed in relief as she didn't pull her gun back out. 

"Don't scare us like that Hawkeye," Roy said. 

"Sorry sir." She replied. 

"Colonel, why didn't you do anything? You're her superior, doesn't she have to listen to you?" Alphonse asked. 

"Uh… r-right, sorry…" Roy rubbed the back of his neck. 

"He didn't do anything because he's scared of her," Ed told Al, "it's one of the few things we have in common…" 

"You… are scared of her?" Denki asked, "but… she's your underling, so she has to listen to you… and… uh… okay I'm confused." 

"I am not scared of her!" Roy was quick to defend himself. 

"Bullshit!" Katsuki exclaimed, "If you aren't scared of her then why didn't you do anything?!" 

"Uh…" 

"Because he's an idiot and forgets that he's my superior sometimes," Riza sighed. 

"Hey!" Roy exclaimed. 

"For someone who's always giving me crap for talking back to him, you sure don't have a problem with it." Ed muttered. Riza glared at him, and he quickly shut his mouth. 

"Can we get going?" Winry asked, "Granny is waiting for us." 

"Yeah yeah, let's go." Ed sighed, starting to walk away. 

"We're not finished," Bakugo growled. 

"Then we can finish tomorrow! Granny's going to kill us if we're home late. Cya!" Ed waved goodbye, and they left. 

¤¤¤

"So you're teaching the Elric's right now?" The black haired woman asked. 

"Yes, along with the number one hero. He isn't with us often however do to personal reasons." Shota replied, "I'd also like to know your name." 

The woman laughed, "Right, Sorry! I'm Izumi, Izumi Curtis. I taught the Elric's when they were little. I'd like to help out." 

"That's a large request. Can you prove your identity?" Shota asked. 

"The Elric's will know who I am!" Izumi laughed, "Don't worry, I'm not here to kill anyone. Although hurting I can't promise. It's part of my teaching style." 

"Alright. We'll see when they arrived." 

¤¤¤ 

"Class, We're going to have someone else helping today with training, hopefully." Shota said, and the entire class perked up. They were outside, ready to go. 

Shota nodded, and suddenly, a woman came flying out of nowhere, and kicked Edward in the face. 

"AGH!" Ed yelped, flying away, as the woman landed. Alphonse squeaked. 

Izuku Curtis dusted herself off, and looked across everyone. Then she went up to Alphonse, who started shaking. 

She roundhouse kicked his chest, and he went flying. 

"AHH!" Al squealed. 

Ed came back over, and squeaked when he saw her. 

"S-s-sensei?!" He exclaimed. 

Alphonse came back, still shaking. He didn't say anything, but both were scared. 

Izumi was silent for a moment, before yelling. 

"LAW OF EQUIVALENT EXCHANGE! GO!" 

"HUMANKIND CANNOT GAIN ANYTHING WITHOUT FIRST GIVING SOMETHING IN RETURN! TO OBTAIN, SOMETHING OF EQUAL VALUE MUST BE LOST! THAT IS ALCHEMY'S FIRST LAW OF EQUIVALENT EXCHANGE!" Both brothers shouted in sync. 

The class stared at them, mumbling to each other. 

"Good," Izumi smiled, "glad you can both still use your brains." 

"It hasn't been that long since we last saw you Sensei, of course not…" Ed said nervously. 

"Did I say you could talk back?" She growled. The small Alchemist sweat dropped. 

"N-no sensei!" He replied quickly. 

"Nonetheless, I guess you're right. Good to see you both again!" She laughed, patting them on the back. 

"Um, excuse me, who are you?" Izuku stepped forward nervously. 

"Hm? Oh, sorry! I forget to introduce myself! I'm Izumi Curtis, I taught the Elric's when they were little!" Izumi smiled at them. 

"She… kind of gives off a motherly vibe, if you know what I mean…" Ochaco mumbled. 

"Curtis has offered to help teach you for the month while the Elric's are here." Shota said, "I expect you to treat her with respect, despite-" 

Shota was cut off by Izumi barfing up blood onto the ground. Everyone backed away quickly. 

"Sorry about that! I won't be able to do much but yell, and maybe hit Ed a couple times. But I'm happy to help!" Izumi smiled. 

"Sensei, if you don't mind me asking, where's your husband?" Al asked worriedly. 

"Here," a deep voice said, and a large muscly man walked up to them. 

"Ah! Sig!" Izumi burst into a huge smile, and hugged him. 

"You shouldn't strain yourself like that." Sig replied, hugging back and then cleaning up the blood mess on the ground. 

"Right, sorry dear! I'll be more careful!" Izumi stared up at him lovingly. 

"Would you stop eye fucking each other already?" Katsuki demanded. 

"Bakugo, be respectful. Izumi came a long way just to help teach you brats. Now get into groups, we're starting. Today is just practicing your quirks peacefully." Shota said, and everyone nodded. 

"Hey Yaoyorozu!" Ed went up the ravenette, "Want to practice together? I want to see your quirk in action!" 

"Oh, sure!" Momo replied, smiling. The two found a nice place to sit, and Momo closed her eyes. An iron pole came out of her arm, and she showed it to Ed. His eyes went round. 

"Okay, that's pretty cool. You just, convert the atoms in your body into abiotic matter?" He asked. 

"Mhm! I need to eat a lot for it to work, so I have the extra atoms." She nodded, "What about you? I have yet to see your quirk in action." 

"Alright," Ed backed up a bit, and shifted into a crouching position. He clapped his hands, and put them on the ground. Blue lightning started flying around, as he moved his hands, and moved them around in a spherical motion, creating a mini castle out of dirt. 

"Wow!" She clapped her hands together, "That's so cool! How did you do that?!" She exclaimed excitedly. 

"Alchemy," he replied, "I could teach you the basics, you seem to be pretty knowledgeable on the value and matter of most objects already." 

"But isn't it a quirk? It's individual to you?" She questioned. 

"I kind of lied when I said Alchemy was my quirk. When I was researching this place, I found out everyone had a quirk. We decided to introduce alchemy as a quirk," he explained, "but it's actually not. Can you create some simple materials and chalk?" She nodded, and quickly made them. A couple blocks of wood and stone, and a metal sheet, along with some white chalk. 

Ed grabbed the chalk, and stared at it for a moment, quickly running through what he could show her. 

"Okay," he said finally, "Alchemy is based on the law of equivalent exchange, which as you heard earlier, means that you must give something of equal value to create something else. In Amestris, anyone is free to learn alchemy, but there are two laws you have to follow, the first is that it's illegal to transmute lead into gold," Ed paused, "not too big of a deal, I doubt you would anyway, the other one though…" he trailed off.

"It's a taboo among alchemists. Not only is it illegal, but impossible, and fatal to try." 

Momo frowned, confused, "which is?" She prompted. 

"Human Transmutation," Ed explained, "the act of bringing a living being back to life." 

"I didn't even realize that could be possible… why is it illegal?" Momo asked. Ed sighed. 

"Carbon (20kg)

Ammonia (4L)

Lime (1.5kg)

Phosphorous (800g)

Salt (250g)

Saltpeter (100g)

Sulfur (80g)

Fluorine (7.5g)

Iron (5g)

Silicon (3g)

And 15 traces of other elements," Ed quoted. 

"That's the recipe of an average human body," Momo said, "I'm confused…" 

"Let me break it down for you," Ed sighed, "remember how to obtain, something of equal value must be lost?" Momo nodded, "That applies to human transmutation as well. The act of bringing a living being back to life, even with alchemy, is impossible, and strictly forbidden. Even if you have all the ingredients of the human body. I can't believe you haven't figured this out, think!" He whacked on the head a couple times with his left arm. 

"Ow! Okay, okay! Thinking…" she hummed, quietly in thought, before it hit her. 

"Because every individual is special," she started, and Ed nodded, "and… nothing can equal to the value of one individual person," Ed continued nodding, "so even if you can create the body…" she clapped her hands together, "you can't recreate the soul!"

"Exactly!" He grinned, "Nothing can equal to the value of a human soul, which renders human transmutation impossible and dangerous. Trying it can be fatal." 

"What are you two up to?" They looked up to see Izumi. 

"Oh, Curtis~Sensei!" Momo smiled, "Elric said he would teach me the basics of alchemy!" 

"Did he? Well maybe I can help, I did teach him after all," Izumi smiled, and sat down with them. Ed sweat dropped a little. 

"So where are you at right now?" 

"I just finished explaining the laws of alchemy, and why human transmutation is forbidden." Ed replied. 

"Good, what's next?" She asked. Ed paused to think. 

"There are three main bases to Alchemy," he said, "Comprehension, the understanding of matter and an object, deconstruction, destroying an object and matter, and reconstruction, using the same matter to build something else. To fully do alchemy, you must understand all three." He paused, "I once met a man who was trying to kill state alchemists with alchemy. He's an acquaintance to us now, but when we first met he tried to kill me with his alchemy. The problem was, all he did was destroy things. Powerful, but not reliable. His alchemy stopped at the deconstruction faze…" 

Ed continued to explain alchemy and how it worked to Momo, with the help of Izumi. Once he was done explaining transmutation circles, she asked a question that caught them both off guard. 

"But you don't use transmutation circles. You just clap your hands. How does that work?

"That's a good question, uhh…" Ed trailed off. 

"That's not something for beginners!" Izumi said quickly, "you probably won't be able to learn that in the month." 

That sounded suspicious to her, but she nodded. 

They made arrangements for Momo to come by after school, and maybe learn more. 

¤¤¤

"Hey Elric?" Momo asked, looking up at him. 

"Yeah?" 

"How did you lose your arm, and where are your parents?" 

Edward froze. 

Alphonse flinched. 

Riza's expression darkened. 

Granny snored. 

Roy took another sip of his beer. 

Izumi's grip tightened on the plate she was washing. 

Winry dropped the plate she was washing. It shattered on the ground, and she flinched. 

"Sorry… I'll clean that up," she mumbled, walking over to grab a broom and sweep it together. 

"Here, let me," Izumi stopped before she could put it in the garbage, and clapped her hands, holding them over the broken plate. Alchemic lightning flashed, and the plate was fixed. 

"Thank you ma'am," Winry responded, forcing a smile at her.

"Oh my, was the insensitive?" Momo frowned, "I'm sorry, you don't have to answer if you don't want to-" 

"No, it's… it's fine, you didn't know," Ed assured her, "our dad… our dad left when Al and I were little, and our mother died when we were 11 and 10. My arm is a longer story… I can tell you some other time, maybe." 

Momo nodded, and they went back to teacher her alchemy. 

"You handled that question well, good job." Izumi clapped Ed on the back after Momo had left. 

"Thanks..." he replied, "When's dinner?"

"Almost done," Izumi replied, "go get ready." 

Ed nodded.

¤¤¤