Disclaimer: I do not own FMA. If I did, Roy wouldn't have said such a mean thing...
Summary: This is just a little something I came up with because I think Edward deserves a little revenge.
Warning: Spoilers for episode 16, I guess. That is where I got the quote from. This is set sometime after episode 16, then.
Edward Elric: I'm going back to my mechanic. You know the one.
Roy Mustang: Sure, Ed, how can I forget? I saw you at her house, unconscious, with that same stump of an arm you have now, bawling in your sleep, "It hurts! I'm gonna pee my pants!" So tough.
Edward Elric fumed as he remembered the colonel's words. That bastard.
Now, however, was his time for revenge, and due to this he smirked. The bastard was in the backroom right now, getting evaluated on if he could get automail or not.
It turns out that Roy had been stupid enough to have his leg ripped off in a battle. The Great Flame Alchemist Roy Mustang lost his leg. The humor was too great for Ed and he stifled a laugh. He was just lucky enough to have been here when Roy came to get automail.
Suddenly the door burst open. Winry appeared, and announced that Mr. Mustang was applicable for automail, and that they would begin the surgery tomorrow.
The next day, Edward sat outside the door listening to the whole thing.
"AHHH!" Roy cried out. "DAMN IT! IT HURTS!"
"Wrench. Screwdriver. Get me a towel!" Pinako said, instructing Winry.
"Is he bleeding?" Winry asked.
"No..." Pinako whispered the last bit, but Ed could guess what she said.
The screaming continued late into the evening, and Edward ended up not being able to see the colonel until the next day.
"So, bastard? You awake?" Edward leaned over the man. Roy opened his eyes.
"Fullmetal?"
"Yes. How do you like your automail?"
"It hurts." Roy replied honestly.
"Yeah, I bet it does, doesn't it? Man, you are a whiner. I, at least, kept my cries controlled while they were doing the surgery."
"Your point?" Roy grew annoyed with the conversation at that point.
"I may have cried out about peeing my pants, but I was young, and at least I didn't actually do it! The Flame Alchemist Roy Mustang PEED HIS PANTS WHILE GETTING AUTOMAIL!" Edward cackled.
"At least I'm not short!"
"But you peed your pants!" Edward let the short comment bypass; this was too humorous to let a thing like that ruin it.
Alex Armstrong, who had escorted Roy, came in at that point.
"Roy Mustang, you need to train! The art of not wetting ourselves has been passed down Armstrong line for generations!"
Edward left Roy to Alex's care; he had his humor, and now it was time for Roy to truly suffer.