Edited as of 7/15/12, and while there are a couple things that could do with improving, I'm happy with the way everything has turned out!
Spoilers through OOTP, and chapter 105 of the manga.
Story cover by NinthFeather!
Protectors of the Earth
Roy couldn't remember ever being so terrified.
He had only a vague idea of what was going on. After losing his sight to the Gate, he had been terribly disoriented and confused. All he really knew was that the Homunculus had brought them all together to make a Philosopher's Stone of the country—and he had succeeded.
What happened next made little sense to him. The man named Hohenheim had somehow reversed the creation of the Stone. He, Edward, and Alphonse were fighting Pride and his Father, judging by the great amount of noise in the room. A small girl also seemed to be there, along with a woman who identified herself as Izumi Curtis; she had taken it upon herself to keep him out of harm's way. Roy didn't want to admit it—even to himself—but without her protection, he would have been dead a long time ago.
Curtis soon left, running to assist the Elrics in the fight. A voice he did not recognize—he called himself Greed—also sped off, leaving Roy under the sole care of the young (Xingese?) girl. She said nothing to him as she—from what he could gather—added defensive barriers around the two of them.
Roy hated being useless.
Suddenly, the room heated up several degrees, and the girl from Xing yelped in surprise. The sounds of battle stopped abruptly, and Roy wondered frantically who had been hit by the fire—lava—sun—whatever the enormous heat source was.
"ENOUGH!" the Homunculus roared, and in the blink of an eye, Roy was grabbed by something—it felt like stone—and pulled through the air. He heard three yells from various other directions, but why was there not one more?
He was slammed, hard, into the ground, and let out an involuntary grunt. Ed let out a horribly desperate cry.
"Edward Elric, this has gone on long enough. You sacrifices have ceased to be useful to me." The Homunculus sounded suddenly irritated…definitely not good. "Either you activate that array in front of you, or I kill everyone here, one by one."
Edward's gasp sounded panicked, and Roy wished—not for the first time in the last hour—that he could see, that he could know what the circle was. Listening to the worried cries from the others, Roy knew it meant trouble.
"Brother, you'll die if you do that!" Al sounded beyond hysterical; his armor clanked loudly as he tried to break free.
"But you'll die if I don't!" Ed sounded as if he either wanted to cry or punch something…it was always hard to tell with him.
"Ed, don't! We'll be fine!" Izumi Curtis yelled, sounding angry and scared. "Don't you dare—"
"I'm running out of patience, boy." The Homunculus did indeed seem to be getting angrier by the second. And Mustang knew, without a doubt, what decision the boy would inevitably reach…even if he disliked his superior officer and seemed to outright hate his own father, he wouldn't just let them die. Nevertheless—"Fullmetal, don't even think about it!" he yelled, sounding as intimidating as he could.
"Edward…" Hohenheim said simply, pleading with his son.
Nothing happened for a moment; there was no crackling of a transmutation, no yelling from any of his fellow captives. Roy wondered what would happen to the rest of them once Edward sacrificed himself.
Metal smashes, and all Hell breaks loose.
"ALPHONSE!" Edward's strangled scream told Roy what he had already deduced, what he hadn't wanted to believe. The Homunculus had evidently decided that Ed had waited for too long. And Alphonse's blood seal—
The Homunculus laughed mercilessly, and a chillingly childlike voice—Pride, Selim Bradley—said, "Well, Edward Elric? What will you do now?"
Ed was breathing heavily now, sucking in air as it if would reseal his brother's soul. Suddenly, there was a clap, and Roy heard mismatched hands meet the stone floor.
He had a pretty good guess as to what the circle was now; nothing but human transmutation could elicit that reaction from the others. Roy realized with terror that Ed would almost certainly not make it out alive if he went to the Gate without any equivalence. He's already lost so much…there's nearly nothing left for it to take. He struggled uselessly against his bonds, trying desperately to help the boy, when a sound from next to him—where Pride stood—made him turn his head.
"Why don't you join him, Pride?" Greed—the apparently rogue Homunculus—sounded almost gleeful as Pride's furious, surprised yells traveled farther and farther away from Roy. They stopped suddenly, and Greed laughed. "Go to hell!"
Roy strained his ears, trying to catch any sort of clue about the situation. Suddenly, the room fell silent; the reaction was finished. "What happened?" he asked frantically, turning to where he knew Izumi and Hohenheim were trapped.
There was silence for a moment, then the older man choked out, "They're…they're gone."
Ed found himself standing in the vast whiteness. He didn't even give himself a chance to get used to the unsettling atmosphere; he had no time; he had to make sure he wasn't too late to save his brother.
"AL!" Nothing answered him, not even an echo. He looked around in the whiteness; he saw only his own Gate, as well as Pride lying unconscious on what passed as the floor. (He wondered for a moment what he was doing there, but there was absolutely no time.) He tried yelling again; his efforts were met with laughter this time, and he spun quickly to see the source.
Truth, in all its glory, waved at him from in front of the Gate. "Here again, Edward Elric?" Its face split into a wide grin. "I thought you might have learned the first three times you came through here…"
"Where's Al?" Ed had no time for Truth's banter. If he had arrived quickly enough, maybe his brother hadn't been pulled into the Gate. Maybe if he were there, in the whiteness, he could still save him. Maybe—
"That isn't important," Truth's many voices said—there were so many, but they were all the same. All is one, one is all. Ed found it difficult to laugh at the irony. "How do you plan to take him out of here? Will you offer yourself?"
"Yes," Ed said immediately, barely able to think. " That's equivalent, right? Take me and send Al back to Amestris—"
"Ah, but you're not a whole person, now are you?" Truth's grin grew wider, and it waved its—his—right hand toward him. Ed realized with terror that he was right. How could I have been so stupid? Of course he wasn't worth as much as Al! He couldn't even begin to compare—"That's not the answer I'm looking for. And unless you come up with that, I've got my own solution…"
But Ed had just remembered. Pride was there—Greed had pushed him into the circle—he was in front of Ed's own Gate, which meant—No! They had sworn to never use a Philosopher's Stone, to never use human souls to correct their own error. It was their own fault they were like this, damnit, and Ed refused to drag other innocents into the equation. He appreciated Greed's thought—at least he knew the bastard cared (or he just figured he'd get rid of Pride along with me)—but it was just not plausible. There had to be another way to save Al; there had to be! He couldn't just leave him at Truth's mercy. Surely there was a way to beat him, to get his brother back—
Truth laughed at the alchemist's obvious distress. "Think quickly, Mr Al-che-mist," it sung. "There's an answer to this…but can you figure it out?"
"Bastard!" Ed couldn't take any more of the "deity's" jokes. It knew why he was there; it knew that he'd rather die than go back without his brother! Why did it think he'd ever agree to anything else it suggested?
The grin slipped off Truth's face at last, and it seemed to heave a sigh. "Too bad…I thought you, of all people, would be able to figure it out. But since I like you two…why don't we make a different kind of deal?"
"What're you talking about?" Truth was not one to cut deals, unless they directly benefitted it. What's the catch?
"If you were anyone else, you'd both be dead," it continued as if he had not spoken. "Trying human transmutation and refusing to use the little equivalency you brought along—"
"What's the deal, then?" Ed asked, getting to the point. He wasn't going to waste time chatting with an omnipotent being when he had a brother to resurrect and a country to save.
"Impatient, are we?" Truth laughed. "I'll send you and your brother to a different world. That'll balance the exchange for now. But if you ever want to get back to Amestris in one piece, you'll have to find enough equivalence and bring it here. For your bodies, and the passage fee."
Truth seemed positively cheerful now, which put Ed even more on edge. "And I won't even charge you a fee to get there! To be quite honest, this is the best thing I've ever offered anyone, Mr. Alchemist," it finished, crossing mismatched arms and grinning over at Ed. "So we have a deal?"
"What? Hang on—"His head was spinning—different world? Al would be there? What was it—
But the Gate was already opening; the black arms stretched toward him and Pride. He knew that he had no say in the matter. They would be pulled into this parallel dimension, alternate universe—whatever it was—and there was nothing he could do to stop it. And—"What about Amestris?" Surely, the Promised Day was still continuing –they couldn't just leave in the middle of the fight—if they lose, he'll never forgive himself—
Truth only grinned.