This idea came to me awhile ago, and it was meant to be longer. But I decided to shorten it since I was a little strapped for time. Thanks for reading and please review! ^^

Disclaimer: I do NOT own, and never will own, any of the characters in this fic.

Happiness. Sadness. Anger. Jealousy. Love. The five emotional staples of humanity. Edward Elric, when he wasn't working for the military dogs as the infamous FullMetal Alchemist, was researching these five unfathomable feelings. Sure, he knew everyone experienced these things from time to time. But most people didn't give it a second thought.

He did.

He gave it more than a second thought. Much, much more actually. Ed was a scientist indeed and always looked at everything with a scientific and critical eye. There was little that couldn't be carefully calculated and figured using some kind of equation or experiment. However, these five little things slipped right under his radar. What exactly caused humans to feel anything?

Edward spent the majority of his afternoons jotting down notes about these strange behaviors. He also experimented on himself regularly. He thought of people calling him short to summon the feeling of Anger or about his brother Alphonse to conjure up a little Happiness. Often, he masturbated. This was a failed attempt to make himself feel Love.

This is what the elder Elric did now, his soft pants filling the empty room as he finished himself off. He glared at the empty sheet of note paper. No notes. While doing this did make him sweat and moan out, it wasn't the same as sharing the feeling of Love with someone else. No... of course not. And so, to complete his research, Edward must need someone else to experiment on!

Hmm... Riza? Ed paled as he thought of an angry Riza, putting her gun to his head and blowing his brains out. Not Riza.

How about Al? A blush replaced the paleness on his cheeks. He loved his brother, but not that way.

That left Roy Mustang, his very smug superior. He seemed like a very nice canidate, fully able to experience each of the five Emotional Staples.

Ed smiled a little before cleaning himself of his release and picking up a new notebook.

New Test Subject: Colonel Roy Mustang

Hair: Black

Eyes: Brown

Height: Taller than me (bastard)

Weight: Around 150.

After filling out Roy's general info, Ed decided to sleep until tomorrow. Then, he would begin his first trial of the new experiment.

Day 1: Happiness

"Hey, Mustang. Do you have any errands you need me to run?" Edward asked his commanding officer, being surprisingly pleasant for a change.

"Well... no." Mustang raised an eyebrow. "But you are being fairly civil today, FullMetal. Is there something you want?"

"Nope, just trying this new thing. It's called 'being nice'." He smiled widely, hoping the sarcasm wasn't too biting.

"Alright, whatever you say. But you are aware it's your day off, Edward?"

"Of course I am."

"And you're still asking to work?"

"Yes, Sir. Anything you need done? Reports, organization?"

"No, thanks. But I appreciate the extra effort, FullMetal." Roy flashed a nice grin at him. Mustang always loved some good work ethic and Edward had used that to his advantage. On top of that, he went to the trouble of fixing Roy some lunch (even if it was a little burnt) and paid him lots of compliments. Each time Roy would ask him if he was for real, Ed would simply reply with a smile that he was just trying to be kind and useful for a change. Finally convinced, Roy thanked him at the end of the day and decided Ed wasn't as big an idiot as he thought he was. He even made it a point not to call him short that day.

Day 2: Sadness

This emotion would be a little hard. But after the great turnout yesterday, Ed had managed to get a ton of good points down into his notes and was feeling pretty motivated. What would make Mustang sad?

"Mustang." Edward said, his voice shaky. With a good amount of water running down his face, Edward looked as if he was crying really convincing tears.

"What is it- FullMetal, why are you crying? Tell me at once."

"It's just that... I found out I'm be dying of an incurable illness! If I die, who'll take care of Al for me?" He let his body be wracked by fake sobs. Mustangs' eyes widened.

"You're... dying?" Edward nodded slowly. "FullMetal... I had no idea. Are you sure?" Another nod. "I don't know what to say. I'm so sorry, Edward, that I haven't been nicer to you. You're the tallest person I know. You're tall and brave on the inside. And when you go, I'll surely be the first to salute you." Roy's eyes are soft and sincere.

"R-really, Mustang? You mean that?" Ed was starting to feel guilty. When he really did die, he was going to Hell. He almost died right then after seeing a tear slip down Mustang's cheek. He resisted the urge to brush it away.

"Of course. You really are an amazing kid, you know that? Well, goodnight, Edward. I hope to see you in the morning."

Ed didn't have the heart to call him back to tell him he was kidding. He felt like shit the whole time he copied down stimulants and reactions.

Day 3: Anger

Edward had a sinking feeling in his gut when he woke up. The feeling didn't improve after Havoc told him that Mustang had been shut up in his office all day and wouldn't tell anyone what was wrong. And now, he was at his superior's office, Riza telling him not to go inside.

"Colonel Mustang is very under the weather today, so don't try pulling anything, Edward."

"Does he know it's me here, at the door?" Ed asked Riza. "Because I'm sure he'll let me in. Please, it's important. Let me speak to him."

"Ed, is that you?" The Colonel's door opened slightly. "Please come in."

Riza's mouth opened and then closed. She stepped aside to let Ed pass.

"Colonel, I-" Edward started before being cut off.

"So, how are you, FullMetal? Any improvement to your condition?"

"Well, that's what I wanted to talk to you about. See, Mustang," He scratched his neck nervously. "I sort of lied. About dying, that is. I'm perfectly healthy."

"You... you WHAT?" Mustang's face went red as he leaned so far over his desk, Ed was convinced he was going to fall off it. He took a few cautious steps back.

"I'm sorry, okay! I know it was wrong and everything!"

"Why the hell would you lie about something like that? I was worried sick about you, FullMetal!"

"No one told you to be!"

"...Get out."

"What?"

"I'm pissed, Fullmetal. Get the fuck out of my office!" Ed turned and ran out, shutting the door right as a boot hit the place he was just standing.

Well, mission accomplished.

Day 4: Jealousy

"Hey, Havoc, do you think you could help me take my shirt off?" Ed asked, his eyes burning with a mischievous fire. He looked over a soon-to-be bare shoulder to be sure Roy was paying attention. "It keeps getting caught in my hair."

"Sure." Said Havoc boredly, not once thinking of Edward's motives. Roy was definitely paying him all the attention.

"Here, let me take my hair out for you." Ed reached up to undo the long, blonde plait and let his hair fall freely across his back. Roy gulped. Was it just him or was it hot in here? "Start with this button, right here. It's the one that keeps getting caught." Havoc's fingers undid the button with ease, exposing just a bit of Ed's chest. "Oh, guess I forgot to wear anything underneath. Sorry."

"Don't care." Havoc spoke around his cigarette. He undid another button and helped Ed to pull the fabric over his head. His tanned chest was completely exposed.

"Thanks Havoc. I owe you one." Ed winked a bit before giving Havoc a quick half hug. Was Roy still looking? Yes. And he definitely was looking a little green eyed. The only thing going through his head was what he could do to get his fingers tangled in that blonde mane. He wanted Edward to himself, even if he was nothing but a liar set on giving him a heart attack!

"Havoc!" He barked.

"Yes, Colonel?"

"As I recall, you have a report due to me early tomorrow morning. I reccomend you finish it before then."

"...I thought that was due this weekend."

"Yeah, well, now it's tomorrow! So go work on it!"

"Yeah, whatever..."

Ed smirked. Roy was right where he wanted him. Right in position for trial number 5.

Day 5: Love

Edward's 5th trial started with his daily routine. He was 'experimenting' on himself again in his quarters. The only difference was that he had called Roy down to 'talk' with him. Of course, Roy had haughtily agreed. And now...

"Mmm... haah, haah..." Edward squeezed his eyes closed tightly and bucked into his hand. "So...good... oh, God..." Of course, Ed didn't actually believe in God. But that was beside the point. He bit his lip hard enough to draw blood as he felt himself go over the edge. "Mustang!" He sprayed himself with his own fluids, panting hard before looking up into a very surprised and very turned-on face. That of Mustang himself. Ed smiled devilishly as he began to lick one digit up and down slowly to gather the thick, white cum onto his tongue. "Nnnng... I was waiting for you, Colonel."

His superior, he knew, was painfully, painfully hard.

"Save some for me, Fullmetal." He ordered, trying not to let his voice crack. He took the other hand and helped Ed clean himself up. After he finished with that, he moved down the little blonde's chest and listened to his long, loud moans. "You sound like a woman when you moan like that." Roy smirks.

"Yeah, the woman that'll be topping you-!" Edward choked out.

"Think again, FullMetal. I am, after all, older than you and taller. You're just a midget. Think of it as compensation for yesterday and the day before that."

"F-fuck you! Ah, ah, ah! God, Mustang, don't stop..."

"See? You do sound like a woman. A very sexy woman, might I add. Take your hair out for me, Edward."

Edward reached up, with shaking hands this time, to undo the plait. He threw his head back and let a loud, satisfied squeal come out. Mustang's mouth was so tight and hot... His fingers twined themselve in thick black hair and he let himself pull Roy's mouth further onto him. After a slight gag, he took all of Ed like a pro.

"Oh, oh, Roy... I'm coming!" Roy hummed in response, causing Ed's body to lock up as he let himself go into Roy's mouth. He readily swallowed all of it, save for the bit on the corners of his lips.

"Still think you're topping me, FullMetal?"

"Shut up and fuck me!" Ed yelled loudly, practically tearing Roy's pants off.

Mustang grinned and undressed before sending a begging Edward into ecstasy.

Day 6: Hypothesis

"FullMetal?"

"Mmm?"

"What is this?" Mustang looked at the notebook, at the pages and pages filled with information about him. Happiness, Sadness, Anger, Jealousy and Love were all successful experiments. Hypotheseis: Emotions are mainly triggered by endorphins and horomones gathering in the human brain to create different behaviors and/or feelings. This is a result of various stimulants and reactions.

"It' nothing!" Edward cried, sntaching the papers away, still naked from last night.

"You're wrong about that last one you know." Edward looked up sharply. A flaw in his perfect conclusion? "What happened last night wasn't caused by Love. It was caused by Lust."

"Huh?"

"It was just hot, passionate sex. That isn't equivalent to love, Edward. Love isn't just horomones or whatever. It's something special."

"You mean, you don't love me?" Edward asked, sounding hurt unintentionally.

"Does that make you sad?"

"Well... yeah.. A little, I guess."

"That's Love, FullMetal. And I do actually love you, by the way. Even if I'm just your glorified sex guinea pig."

"...Hmm..." Ed stepped over to the desk. He took all of the pages of the research and tore them before throwing them out.

"Why did you do that? According to one of those, you've been researching this for months."

"...I don't need them, idiot. I can experiment and not write down the results, you know." He smirked before pulling Roy's boxers down.

"Yes, Professor Elric."