Chapter Text
“You’re doing it again.”
Mustang’s voice was sharp and irritated and at some point while Ed was distracted mumbling to himself, he had moved from behind the desk around to the front and leaned back against it, one ankle over the other and arms crossed over his chest, glaring at his young subordinate.
“I—what?” Ed stuttered, looking wide-eyed at Mustang. Ever since the last report he’d given, where Mustang had taken off his uniform jacket and he had been sweating and gorgeous and Ed’s teenage hormones had gone into hyperdrive, it had been a lot harder to control himself around his commanding officer. Which brought him to this situation: almost a full month later, sitting in the exact same position, on the exact same couch, failing to deliver yet another report because Mustang was looking at him with those smoldering eyes of his and Ed’s pants were suddenly too tight so he had to break off in the middle of a sentence too cool himself back down.
“For some unknown reason, you’re reciting the entire periodic table at me. Again.” Mustang let out a dramatic sigh. “Last time I thought it was just the heat going to your head, but since the weather’s cooled down since then, I guess it’s just you purposely wasting my time.”
“Oh, right, because everything has to be about you, doesn’t it, Colonel?” Ed snapped. Even if it was because of him, Mustang didn’t need to know that. Besides, Mustang being an asshole made everything easier for Ed. He could just whip back a snarky retort instead of focusing on how unbelievably attractive the man was.
“Look, Fullmetal, I know you’re eccentric, but I really don’t have time for this right now. Just finish telling me about the mission, and you can go be strange somewhere else.”
Ed rolled his eyes. “Fine. So, anyways…the library in that town was a dead end, but Al got to chatting with the locals and he found out that—” Glancing sideways at Mustang, he saw the man leaning his weight on his hands braced behind him on the desk, making his hips stick out a bit and the short uniform jacket ride up slightly, exposing the white shirt underneath. Ed swallowed and continued, “He found out that the freaky weather was originating from the river up the mountain.”
Mustang’s head was cocked slightly at him, his hair was falling over his eyes, and he was looking so fixedly at Ed, focused on nothing but him, and to be at the receiving end of that kind of attention from Mustang was severely distracting.
“So, w-we went to check it out.” Ed cleared his throat, adjusted his position on the couch, crossed his leg over his knee. “And there—there were definitely signs of, uh…alchemic ac-activity and uh…” Mustang was still just looking at him and why was just him looking affecting Edward so strongly? People looked at him all the time. With his bright yellow hair and his garish red coat and his goddamn metal limbs. Edward was used to people looking. And the only reason Mustang was looking at him right now was because he was speaking, and Mustang was obligated to listen to him as part of his job. Technically, Mustang was being paid to look at Edward right now, so it’s not like he was doing it by choice.
Then again, Mustang didn’t have to look at him to listen to his report. He could sit behind his desk and skim over the written version as Ed talked, or fiddle with a pen or something. There was no need to stare so openly and fixedly. And there was no reason for Ed to be so bothered by it.
“And so we—we…uh…we—fuck.” He clapped a hand over his face to hide his reddening face and started muttering again, from where he had left off before. “Silicon, phosphorus, sulfur, chlorine, argon—”
“Dammit, Ed,” Mustang hissed. “Why are you doing that?”
Ed gulped. “It helps me focus,” he semi-lied.
“Focus on what?” Mustang had reached his allotted quota of patience for the day, apparently.
Anything but the overwhelming desire to jump your bones, Edward very adamantly did not think. “Just—y’know—focus.”
“On what?” he barked and—oh no. He was even hotter when he was angry.
“Potassium, scandium, titanium, vanadium, chromium—”
Mustang stalked over, gripped Ed by the shoulder hard and shook him. “Fullmetal, I demand you explain what the hell you’re doing at once. It’s getting on my goddamn nerves.”
Ed’s hand fell away from his face and he looked up at Mustang looming over him, practically seething, and maybe he felt a little lightheaded. “I—I’m just…uh…I just—”
Mustang took in Ed’s red, flushed face, the tense line of his body, the awkward position of his leg over the other and something seemed to just click behind his eyes, and then he was smirking and Ed knew it was over for him.
“Well, then.” Mustang let go of his shoulder and straightened up, looking down at Ed sitting in front of him. “Looks like someone has a little crush.”
Ed growled, but it didn’t stop his cheeks from staining an even darker red. “Shut the hell up, don’t make fun of me.”
“I would never,” Mustang said in a tone that said he definitely would. “I was a teenager once too, you know. So, what is it, you recite the periodic table and it helps you, what? Cool down?” That was definitely a smug smirk on his face and Edward wanted to punch it off. Or maybe kiss it off. Or both.
“Yeah, I guess,” Ed mumbled, looking away and begging his cheeks to get it the fuck together already. His dick, too.
“Most people just picture their parents naked,” Mustang chuckled. “So how does it work? Do you just recite the names in order?”
“It helps to think of each element’s characteristics as I go.”
Roy nodded like it made sense. “Interesting. Is it a successful method?”
Ed shrugged. “Usually.”
“Usually? So it’s failed you before?” Ed frowned. Why was he asking so many questions about this? “What is its efficiency percentage?”
“What?”
Mustang shrugged and slipped his hands in his pockets, angling his hips just slightly while grinning down at Ed. “You’re a man of science, aren’t you? So you would have chosen the most efficient method of coping after continuously experimenting and testing its success, wouldn’t you?”
“That’s not—”
“Have you tested it under extreme pressure?” Mustang asked, and his voice had taken a smoother, silkier tone, lower than his usual speaking voice and Ed swallowed thickly.
“I don’t…I don’t know.”
And then Mustang’s smirk was dangerous. “As a fellow man of science, I would be happy to help you test this method further.”
“You—I—what?” Ed’s fight-or-flight instinct suddenly kicked in and for someone who’s knee-jerk reaction was usually ‘fight’, he simply sat there, freaking out internally while Mustang leaned down closer to him.
“Go ahead, Fullmetal,” Mustang purred and Ed’s knees turned to jelly. “Start. From the top.”
“But I—” Mustang was inches away from his face and Ed was trembling. “Uh…hydrogen…”
“Non-metal,” Mustang said softly.
Wait, what? “Helium…”
“Noble gas.” His hands came out from his pockets to brace himself on the back of the couch, one hand on either side of Ed’s head, caging him in.
“L-Lithium…”
“Alkali metal.” Mustang leaned in, ran the tip of his nose over Ed’s cheek, near his ear.
“Beryllium…”
“Alkaline earth metal.” Mustang’s lips brushed against his jawline.
“B-Bor-ron…”
“Metalloid.” He used his knee to shove Ed’s leg off of his other leg, then pressed it down on the seat in the newly-formed gap between Ed’s thighs.
“Colonel, I—” Ed breathed. He sucked in a huge breath and held it, willed his heart to not fly right out of his chest.
“Keep going, Fullmetal.” Mustang’s lips were on his ear now. On his ear. His voice was melting straight into Ed’s brain, and his lips were silk-soft against his earlobe and his breath was warm and damp and Ed’s flesh toes actually curled a bit. He was so hard it hurt.
“I—I don’t…remember—”
“Carbon. The next one is carbon.” It felt like a kiss to his ear.
“C-C-Carbon.”
“Non-metal.” Teeth grazed his earlobe and Edward gasped. And just like that, it was ruined. He would never be able to use this method when he was worked up, because all he would be able to think about is Mustang over him, around him, murmuring in his ear and pressing his lips and teeth so gently against his skin. Ed would never be able to look at a chemical equation again without getting a hard-on. Mendeleev would be disappointed.
“Colonel, I can’t—” Can’t what? Can’t breathe? Can’t move? Can’t think?
“Is your precious method failing you, Fullmetal?” The tip of a hot, moist tongue snuck out to tease Ed’s poor abused earlobe and Ed was panting a little bit. “It doesn’t hold up under pressure?”
There was a hint of amusement under Mustang’s words and Edward had really had enough.
“Bastard,” he growled, and raised his hands to grip Mustang by the front of his uniform and tug him in to crush their mouths together. Ed had never kissed anyone before, but that didn’t stop him from assaulting Mustang’s lips, licking and nipping them as much as he could.
Maybe he’d taken it a little too far and Mustang would shove him away angrily and have him court-martialed or something, but what did he expect, teasing him like that? Ed was a hormonal teenage boy and the object of his affection was practically in his lap and abusing his earlobe with his teeth and tongue. Ed wasn’t exactly famous for his outstanding self-control.
But Mustang wasn’t pushing him away. Mustang was pulling him closer, returning the kiss with licks and nips of his own, and Ed found himself being guided by Mustang’s mouth, being taught where to move and where to touch. Mustang’s hands came up to cup either side of Ed’s face and Ed curled his hands tighter in Mustang’s uniform.
There was a pressure between Ed’s legs and he gasped as Mustang’s thigh ground into his crotch as Mustang kissed him harder. He let out little noises of distress and pleasure and Mustang swallowed each one, fingers curling in his hair and teeth scraping against his bottom lip.
Ed had never been touched like this before, had never had anyone over him and pressing against him like this, and Mustang was strong and thick and beautiful, so Ed had no shame in rutting up against his leg like a dog, had no shame when it suddenly became too much and Mustang groaned in response to Ed’s high-pitched whine when he came in his pants.
Ed crashed down against the couch, panting and blinking blearily up at the man still leaning over him. His hands slackened in their grip and fell to his lap and Mustang was off of him like he’d been yanked back, wide-eyed and terrified.
Mustang swallowed thickly, made a hasty retreat to his desk, sat down and put his face in his hands.
“What are you doing?” Ed asked drowsily.
“Picturing my mother naked,” Mustang replied and it sounded like he was in pain. Edward couldn’t help the laugh that bubbled out of him. “You think this is funny, Fullmetal? I just assaulted you. You are my subordinate.”
“Hey!” Ed protested. “That wasn’t assault. I was all for that.” He rolled his head on his neck lazily, dopey from the hormones flooding his system. “I’d love to return the favor, by the way.”
Mustang looked like a scared child. “That—That’s a terrible idea. You.” He cleared his throat. “You are dismissed, Fullmetal.”
Ed frowned and, resisting the urge to pout, got up on wobbly legs and adjusted his uncomfortable pants.
“However,” Mustang cut in as Ed started walking towards the door. “You could…er…come by my house later tonight.” Ed shot him a baffled look over his shoulder and Mustang quickly averted his eyes, pretending to focus on some paperwork on his desk. “You need to finish that report, after all. And we could…discuss the periodic table. As a pair of scientists, of course.”
There was the classic Mustang smirk, coupled with a mischievous glance of those dark eyes, and Ed grinned brightly.
“Right, right.” He turned and waved over his shoulder. “I guess I’ll see you tonight. Y’know, for science.”