When I first got this idea, I thought "No, Ed and Roy would never be that crazed to do something like this!" then I remembered four words: Full Metal vs. Flame. And I remembered not to put crazed endeavors past either of them, especially Roy. So, enjoy, and excuse me if some of this seems a bit out of character for them...
"Brilliant, Mustang. Because of your 'superior' intellect, we're locked in." Ed grumbled running his hand along the wall. The corridor was pitch black and he stumbled to keep his balance, "I can just hear the lecture I'll get from Winry for being late!"
Roy swallowed nervously as he was sure he could hear that lecture too, and elected to change the subject, "The emergency supplies should be just up ahead," he stated, squinting into the darkness as if expecting to see better that way. He felt his hand slide over a door and stopped, "I think I found it."
Lightning seemed to strike the second he opened the door, temporarily illuminating the small room. Roy walked inside and felt his way around. Ed could hear the shuffle of a few boxes as thunder rolled through the rain outside.
"Here we are!"
Ed heard a snap and the small room was lit by an equally small candle. Roy took out two portable lanterns from the box and enflamed them before blowing out the candle. He handed one to Ed and continued to rummage in the box.
"Here's a question," began Ed.
"Why can't we just use alchemy to get out?"
Roy sighed, handing him a few blankets and pillows, "Edward, we get hundreds of alchemists milling in and out here every day. Do you honestly think Central HQ doesn't have wards for that? Who knows what kind of alarm we'd trip trying to open a lock?"
"I guess you're right," Ed tried to say through the pile of pillows. Roy stepped out of the room, closing the door behind him, and took a set of bedclothes from Ed.
"I'll be sleeping in my office. Don't wander anywhere you wouldn't be permitted during the day." Roy explained as he began to walk away, "Since you haven't eaten all day, there should be something in the cafeteria's pantry." he stopped, "Oh, and by the way, there should be a stepstool near the sinks if you find you cannot reach some of the shelves." And without another word, Roy continued on into his office.
"Why would I need one?" Ed yelled indignantly before stomping off in the other direction. It took him quite a lot of time and wrong turns before Ed made it to the kitchens.
"Jeez, finding your way is a lot harder in the dark," he murmured to himself, holding his lantern far in front of him.
"Where is he?" Winry complained outside the small cafe, tapping her food to diffuse her worry, "He was supposed to meet me here as soon as he got done!"
"He'll be here," Al's echoey voice assured her, "He said he just had a few last minute documents to go over with the Colonel and he would be right over. They're probably finishing up right now."
"But he said he'd meet me at eight at the latest and it's already ten!" Winry fingered the hem of her blouse, "What if he's done something to Ed?"
"Colonel Mustang would nev--"
"Maybe he has him under interrogation, or..." she gasped, "Torture?" Several visions of Ed in various torture devices while Roy cackled manically came to her mind.
Roy turned over in his sleep and sneezed.
"All right, pantry. What have you got good?" Ed asked the cabinet as he swung open the doors. Shelves upon shelves of military bulk foods greeted his gaze. Giant cans of soups, sauces, condiments, boxes of crackers, spices, instant noodles, beverages. All were at his fingertips. He decided the instant noodles would probably be the best thing since he wasn't really up to downing a bulk sized can of tomato sauce. He walked up to the shelf and reached for the noodles... and reached... and reached some more...
"Damn! Mustang was right!" he complained out loud, pushing a heavy crate of oranges under the shelf. He climbed up on the crate and took the noodles. He was about to climb down when, "Well, well. What's this?" Ed reached behind the noodles and pulled out a giant can of maple syrup. He glanced back to his pillow, which he left on a counter... How fluffy and... full of feathers it was. A devilish grin spread across the teen's face as he pulled the syrup from the shelf and plopped it onto the counter. He clapped his hands together and transmuted his automail into a small spear, which he used to rip a large hole in his pillow.
"Oh Colonel..." he cooed evilly, hefting his pillow and can of syrup under his arm.
Ed used his transmuted automail like a can opener to open the syrup. Everything was ready... He took a deep breath.
"MUSTANG!" he yelled at the top of his lungs. As Roy sat bolt upright, Ed dumped the can of syrup over his head and ripped the feather pillow completely open. Roy leapt off of his hard office sofa and looked around, blowing feathers out of his eyes. Like a flash, Ed was gone and out of Roy's office faster than you can say "toasted alchemist".
"All right, Full Metal..." he said, smiling, "I'll play your game."
Meanwhile, Ed had hidden himself in a closet, reveling in his accomplishments. Roy wouldn't be able to navigate half-asleep in the dark to find him in such an obscure place. Sure enough, however, he could hear his voice ring through the hallway.
"Okay!" Roy called, "You got me! We've both got things we need to do in the morning, so let's call it a night. I'm tired, you're tired and I'm stopping this right now."
Ed listened for a few more seconds. Silence... He cautiously opened the door and looked around. Down went the bucket bulk of apple juice over his head. Out went Ed's lantern. Snap went Roy's fingers. Boom went the nearby sack of flour.
"I see," he murmured with a slight manic tone to his voice, "So you fight dirty, eh Colonel?" Ed looked around, but saw nothing in his now dark surroundings, "That's right! Hide! I'll get you bett--" a sharp pain erupted on his skull as three eggs cracked over his head. Ed looked around again, but he still couldn't see Roy anywhere. Then a quiet voice whispered in his ear,
"THAT'S IT, MUSTANG! YOU'RE GOING DOWN!"
And that's how Ed and Roy's Prank-A-Thon began.
Ed slammed himself back inside the closet and groped around for something useful. His hands fell on something long and round, giggling evilly as he stroked the red metal device. He burst out of the closet, lightning flashing across the sky as he pulled the pin and aimed the fire extinguisher around. He had a brief view of his surroundings and Roy was nowhere in them.
Roy was in shower room supply cabinet, arming himself with liquid soap, cans of shaving cream, and other various things one would use to make a mess. However, Roy thought that melon-cucumber messes were ideal... above all.
Ed was back in the kitchen, collecting some of the more portable bottles and cans of messy and sticky substances... He also ran hot water in his cup of instant noodles and set it to the side to cook. He was still hungry after all.
Both men were armed and set out, sneaking along Headquarters with only the occasional lightning flash to guide them. For all they new, they could've passed their targets twice and not known it. Adrenaline was running high.
"Are you sure this is a good idea?" Al asked as he hefted Winry over the gate to Central HQ.
"Honestly, have a little faith," she replied opening the latch to admit Al, "Ed is never late for anything unless he has a good reason! Something's wrong! I know it!"
Al sighed and followed Winry to the large doors.
"Now..." she murmured, "The box that controls the security system should be right aboooout, ah! There it is!"
"Shh! There's the night watchman!" Al hissed. The two of them leaned against a post until he passed and continued the process of breaking in. Winry pulled various tools from hidden places on her person like a spy would draw their weapons, smiling at the security system control. It was just screaming to be taken apart.
Roy was rounding another corner, shaving cream cans poised for attack. No one there... He continued down the hallway until he heard a clunk and a "Shh!" from far off.
"So there you are!" he said slyly to himself as he advanced quickly down the corridor.
Farther away, Ed was ready with his fire extinguisher. He was getting closer, he heard the loud clanging...
"I shall soon catch my prey..." he stated manically, a grin plastered to his face.
"Your ability to break in frightens me," Al whispered to Winry as they crept through the dark halls.
"Oh no, it's ridiculously easy to break into here, it's not funny. You should really tell them to get better security. And could you not walk so loud? Someone could hear us!"
"Sorry," Al replied, trying to walk on tiptoe to reduce the loud klanking, "I can't help it!"
"No, I'm sorry. I guess I'm just ner--"
"FOUND YOU!" screamed Ed and Roy at the same time as they caught what they thought was each other in a tsunami of foam and shaving cream. Ed only stopped when he felt the familiar pain on his forehead as a wrench fell to the floor.
"Winry?" he asked the air instinctively as Roy lifted his lantern and lit it with alchemy. There stood Al and Winry who looked nothing short of snowmen. Winry stomped over to Ed and glared him strait in the eye.
"Edward..." she said through clenched teeth, her voice quavering, "What is going on?"
"I was worried to death about you!" she cried, "I had no idea if you were hurt or dead! And here you are! You stood me up to play games?"
All the males flinched at the amount of female anger that was rising as they realized just how narrow the hallway was. After a brief scolding from Winry, Ed and Roy got to work cleaning and had to hear another lecture from the Fuhrer that morning.
"Good morning, Colonel" Jean said dully as he walked into Roy's office. Roy had his head on his desk and Ed had sacked out on one of the office sofas.
Roy mumble incoherently as acknowledgement.
"I just came in to tell you two that if that ever happens again, there's a key in everyone's office so that you can open the doors from the inside." he stated, opening a drawer in Roy's desk and pulling away a compartment door that contained afore mention key.
"Havoc," Roy mumbled, not lifting his head.
"I hate you."
"Obliged, sir. Have a good day."