Be warned: there are massive spoilers involved, especially for the latter episodes of the manga (FMA: Brotherhood), although a few of these are completely non-canon.

For an explanation of the prompt chosen, (and the owners of the songs used as the prompt words), see Ninthfeather's matching story, 20 Sentences: Edward Elric.

20 Sentences: Roy Mustang

Again

Hawkeye started in on her 'you do not torch the paperwork, Sir' speech as soon as she smelled the smoke in his office, and as he sat there, smiling, he wondered how many times he'd done this for the simple fact that it is, and always will be, a constant in their lives - and in all reality, for the fact that it's somehow perversely satisfying to eliminate a minor nuisance in such a manner.

Careful

He smiled politely at the Fuhrer, all the while making mental notations on the placement of everything in his office, because the simple details were the ones that would make or break his plans to eliminate the corrupted man.

Colors

He saw only red as his Lieutenant was injured - the red of her blood, soaking through her military jacket, covering the floor in the bright crimson color, the symbol of her life slipping through his fingers as he failed to staunch her wound, another red stain upon his hands.

Hero

"The Hero of Ishval" they called him, and he laughed maniacally those nights when he was drunk enough for Maes to get part of the truth from him about what had happened there - and found the reason he never spoke about it was more horrible than Maes could have ever imagined.

Hologram

Every night he saw the same thing, a never-ending reel of pictures, memories, that played through his mind again and again, and he knew that he would never be able to rest until he had overcome the agonizing guilt that was an open wound on his heart.

Ignorance

Ignorance of the ways of the world had led him to the military, because he had still believed that everything would be all right in the end no matter what happened, but that hadn't lasted long - in fact, it was one of the first things to disappear.

Invoke

It was unheard of for an alchemist to call on deities, but when he'd learned of Hughes' death, his pleas that it wasn't true, given to whatever beings might be listening, were constant until he had seen the proof with his own eyes, and then they became promises of death to whomever had performed the heinous crime.

Lie

Effortlessly brushing off questions aimed at certain topics was a hard-won skill, however much Fullmetal protested that his commanding officer had always been able to talk his way out of trouble.

Light

"Where's the light," he asked Fullmetal as he tried to stand, falling because he was unable to gauge distance in the perpetual darkness that covered his eyes after the blinding whiteness that surrounded the Gate.

Maze

For some reason, the concentric city streets of Central had never seemed impractical until now, when he had no idea where the Elrics were and the streets simply circled around in never-ending loops, confusing the source of the screams and the sounds of crumbling architecture.

Moment

He looked around the room, at all the smiles as the jokes and gentle banter flew between his subordinates, and reflected that for just this moment, whatever happened elsewhere, all was right in his world.

Period

Watching the sunrise had always brought a bit of sadness to his heart, because despite its inherent beauty, it meant that the short respite of night had passed and he would once more be facing the ones he needed to destroy.

Pieces

Picking up the pieces of others' lives had become a lifelong habit of his, and he never failed to complete the puzzles that made up their lives, but for some inexplicable reason, he had never been able to piece together his own.

Pride

There was no way he was going to let Hawkeye know he'd been shot, telling himself that there was no need to worry her over such a minor wound, because sometimes, his stubborn pride overrode even his loyalties to his team.

Rain

He didn't hate the rain, although it made his version of alchemy fairly useless, because for that short time he could feel like he had been washed clean of the blood that would always cling to his Pyrotex gloves.

Synchronicity

He and Riza had never needed words, not when a single glance could read his intentions and refute them by implying something as simple and honest as "I'll shoot you to death if you perform human transmutation."

Trap

Ed frowned back at his Colonel from across the chess board, wondering how someone so strategically minded could be so easily trapped and destroyed at a game, and then realized that Mustang was so focused on keeping all of his pieces alive that he'd forgotten to safeguard his king.

Uninstall

After Ishbal, he wished that he could erase all of his memories, or that it was possible to go back and stop his younger self from learning such a destructive form of alchemy - or any alchemy at all, for that matter - because it had been that knowledge that had forced him to cause so much pain and death.

Vestige

With the realization that he would be no better than the homunculus if he killed Envy out of his grief and anger, he let loose the last of the hatred from his heart along with the snap of his fingers into the alley and collapsed to the ground, utterly spent.

World

Power for the sake of power had never appealed to him, not when he was a Private, and not now that he was the Fuhrer; but with that power he could change his country, his world, for the better, and perhaps help heal some of the wounds Amestris had sustained over the years.