Been a busy few weeks. As always, interest in my other fics has ebbed and waned, and so I have started yet another project (lol). I've always been interested in crossovers between RWBY and FMA, but nothing ever quite scratched that itch, so I've started writing this up. My knowledge of both series is limited only to a single viewing of FMA:Brotherhood and RWBY up till Volume 6 thus far.

Hope you enjoy!


"That's not possible, little alchemist."

What the hell?

Five words. Five simple words. As soon as they left the lips of the white, featureless being, what confidence Edward Elric had was promptly shaken.

"W- what do you mean?" he stammered, regaining his composure with a look of fury in his eyes. "You said it yourself! This thing is my portal of truth! I get to make the decision on how it's used!"

Truth began chuckling, slowly at first, then gradually picking up in intensity. Edward glared at it in annoyance, ready to demand just what was so funny, when its laughter finally died down.

"Did you forget what I told you first dared to play God, oh little Edward Elric?" Truth spoke, a look of amusement on its face. "You asked me who I was. Do you remember? I am called by many names."

'I am the World. I am the Universe. I'm God. I am Truth. I am All. I am One. And I am also –'

"Me," Edward echoed hollowly, as horrified realisation sank in. "I can't sacrifice the Gate without also giving up myself…"

"That's correct, alchemist!" Truth clapped its hands loudly, lips stretched widely in a grin. "So, then. Back to the question. What will you sacrifice, Edward Elric? What will you give for your brother's body?"

Edward couldn't answer, but things couldn't end this way. He refused to believe that there was no way that both Alphonse and himself could be brought back. They had fought homunculi that each possessed power of the Philosopher's Stones buried within their bodies. Hell, just scant minutes ago, they had battled Father who had created them all, one who had the power of hundreds of thousands at souls in the palm of his hand. He had fought one-on-one against a being that had dared to claim the power of God.

There was no such thing as impossibility. He had to think, damn it! Alphonse's life depended on him!

His mind raced furiously, thinking over all the possibilities at hand.

"Oh? That's a rather scary look you have there, alchemist."

Edward ignored Truth's words. There had to be a solution.

Equivalent Exchange. That was the fundamental law of alchemy. He had thought giving up his own Gate and thereby the use of Alchemy was the answer, but it clearly wasn't.

What, then, would be equal to the value of his brother's body?

What could he give up?

Even after what felt like hours, no answer came to his mind.

"Do you give up, alchemist?"

He stiffened, startled, at the sudden interruption from Truth. The formless being still stood in his same spot, a display of serenity despite lacking any discernible feature beyond its mouth, looking patiently at Edward.

"Hell no!" he snapped. "I'm getting Al back no matter what!"

"Such determination," Truth said, nodding, then sighed loudly. "A pity. There is nothing that you can offer that would both allow you and your brother to return home with your bodies."

No.

Edward slumped over, his knees hitting the groundless floor. Truth's words echoed around the endless white expanse.

His words were absolute. Factual. Unchanging.

They were Truth.

"Normally, I would punish one who would think themselves capable of playing God, but that is hardly the case with you, hmm?" Truth hummed, finally beginning to walk over to Edward. "Yes, yes – I am You, and I am All. It is not pride and hubris that brought you here to me, but desperation and humility. And yet it seems that you cannot pay the toll. It appears that we have a conundrum on our hands."

"There has to be a way," Edward insisted, his voice coming out barely louder than a whisper. He'd promised Al that a body would be waiting for him at the end of all this mess. It couldn't end like this! "My arm… take my arm. Take my legs. Just please… please bring us both back –"

"Will you ever quit your mindless begging and listen?" Truth interrupted harshly, although there was no real bite in his words. Edward looked at him numbly. "You cannot pay the toll for the return of both your original bodies to Amestris, but that doesn't mean that you and your brother cannot ever simultaneously exist in the physical world with your bodies intact."

That… that didn't make sense. He couldn't leave the Gate without paying a toll, but paying a toll to return with Al meant by definition that he would need to sacrifice his life. Leaving without Al might allow him to return to Amestris, but there way no way in hell that he would leave his brother behind in this place.

He glared at Truth, but the being remained silent, looking on at him with a mix of amusement and anticipation.

Think…

Equivalent Exchange. The toll. The Gateway. His mind was awhirl with concepts. He had to break the problem down.

First and foremost, leaving the Gate with Al. Truth said that it was impossible for them both to return through the Gate to Amestris, but there was a way for them to exist in the real world with their original bodies.

The simplest answer, then, was that they had to return without their intact bodies. Al with his armour, and himself without his arm.

Still, that wasn't the answer, and he knew that Truth knew it because the bastard still had that damned smile on its face. Everything they knew about alchemy told them that it was impossible to achieve such a transmutation without the use of a Philosopher's Stone, and both he and Al had sworn off ever using a Stone for such a selfish purpose.

Try as he might, he still couldn't find the damned answer that Truth was looking for.

"What if I told you that the Amestrian alchemy isn't the solution, Edward Elric?" Truth hinted. "Nor does the answer lie with Xingese alkahestry, or the original alchemy of Xerxes. Likewise, there is no known method for what you seek in the practices of alchemy in Drachma, or Creta, and Aerugo."

"But those are all the major alchemical powers of the world –"

He stilled, pausing mid-outburst, eyes wide at the implication.

Truth couldn't possibly be suggesting what he was thinking, could he?

"It looks like you've found the answer, little alchemist," Truth said nonchalantly. "Well?"

"It can't be," he said slowly. "You're saying that there are other forms of alchemy? That other worlds exist?"

"Bingo!" Truth snapped its fingers, the unnaturally loud sound startling Edward. "Your answer lies within a world known as Remnant. For the toll that you can pay and that you are willing to pay, that is as much as I can tell you."

Remnant. The word meant some part of a greater whole that was left behind.

Something like their bodies.

"And Al?" he prompted immediately. "How's Al going to join me?"

Without a word, Truth snapped his fingers once more, and just as suddenly the entirety of the white nothingness was his domain of Truth changed in an instant.

In front of another Gate that appeared from nowhere, there stood the emaciated body of his brother, a form he had glimpsed only once before when he had opened the Gate to escape from the depths of Gluttony's belly.

"Al…" he whispered, his throat suddenly dry.

"I can assure you, Edward Elric, that your brother is aware of our little conversation here," Truth said dryly, before his voice perked up excitedly. "Well? What will it be?"

"Al!" Edward shouted, ignoring Truth momentarily, rushing over to his brother. "Al! It's really you!"

"Brother," he greeted weakly. "You did it. You beat Father."

"Yeah," Edward spoke numbly. "I tried to bring you back by giving up my Gateway, but –"

"I know," Al interrupted. "I heard everything."

"You… you're not mad at me?"

It didn't make sense. It was his fault that Al had to sacrifice his soul in order to restore his arm when Father had him pinned down. Al should have been furious with him, and yet –

"Why should I be?"

"I promised you that I would get your body back…"

"It doesn't change anything, Ed." Edward glanced upward, stunned, as despite the frail body his brother still possessed, Alphonse glared defiantly at him. "So what if I'm going to have to get back to that suit of armour? It's been our life for the past five years. Now, we know that it is possible to get our bodies back without using the Stone."

For a moment, Ed stared at Al uncomprehendingly, before beginning to chuckle as his words sank in.

Damn it. His brother always was the smarter and stronger one of them both.

"Yeah," he echoed Al's sentiments, voice rising in amplitude. "Yeah! We'll go to this Remnant, and we'll find out just how to get our bodies back!"

Sure, it would mean that they would have to leave the rest of them in Amestris behind, but all they needed to do then was find a way to return once they had their bodies back. If returning their bodies was possible, there wasn't much else that was impossible.

"Perhaps you both would be willing to indulge in a little request of mine, hmm?"

They both flinched, turning immediately to face Truth. How had they both forgotten that that being was still there?

"There exists one in Remnant much like the one you called Father," Truth continued smoothly, ignoring how both brothers stiffened at the mentioning of the original homunculus. "This being seeks to play God, to wield powers beyond her domain. Alas, I am unable to personally impose punishment upon this one despite the prideful hubris she has shown."

Another one like Father?!

"Another homunculus?" Al asked incredulously.

"She is neither human, nor homunculus," Truth said, then spoke more firmly before they could continue with any more of the many questions that they both had. "This is the deal that I offer you – fix this little annoyance, and I will give you a little… head-start, in a manner of speaking. Equivalent exchange, no?"

"You want us to kill her?" Al blurted out, appalled.

"Kill, punish, maim – it doesn't matter to me. So long as her arrogance is contained and that she pays a toll for daring to reach the heights of a God, your methods of achieving this outcome matter not. Who knows, perhaps if you do a good job, I might just be inclined to… facilitate an exchange."

Ed exchanged a silent look with his brother, before nodding slowly toward each other. They knew precisely what the other was thinking.

With their bodies or not, there was no way they could sit idly by while a being that Truth compared to the likes of Father ran rampant, even if she was in another world altogether. Father had attempted to use the souls of all fifty million civilians of Amestris to create a Philosopher's Stone that would allow him to consume God. Ed had no idea what it was that this enigmatic 'being' was planning, but to even be compared on the same scale as Father meant some serious business.

Besides, if this 'Remnant' was the only way that they could obtain their bodies back, then they might as well accept Truth's deal, right?

"We accept." Ed asked with all seriousness, speaking on behalf of them both.

"Excellent!" Truth clapped his hands excitedly.

"What did you mean by a 'head-start'?"

Without warning, Truth stepped forward, his face entirely unreadable, and placed a hand on each of the two brothers.

"For it is in despair that humans arrive at the Truth. Through this, they learn the nature of All and of One. Infinite as the Universe, and limited as the Self, I release your soul, and by my will, enlighten thee."

Edward gasped loudly, as something shifted within him. By his side, Alphonse reacted no different.

This sensation – it was warm, and yet not unbearably so. If he had to put it to words, it was almost like the time back when he had been mortally injured by Kimblee, when he had transmuted his own life force to heal his injuries…

"What the hell did you just do?"

Truth said nothing, a wide grin on its face. Both Gates swung wide open.

"Hey, you – hey! Answer me!"

Black tendrils shot forth from the Gates, wrapping themselves around both himself and Al, and yet they didn't have quite the same feel as back during the fallout of their failed attempt at human transmutation. Sure, they still squirmed unpleasantly around him, but this time they didn't have quite the same suffocating sensation as though drowning in a pit of mud.

"Oh, before I forget. The one you seek is known as Salem," Truth said as though an afterthought, just before they were about to be dragged through each of their Gate. "Good luck, little alchemists. You'll need it."

With that, they were both brought through the Gate. The world of Remnant beckoned.

-o-o-o-

Again, what felt like an endless stream of information entered his head, and yet this time it felt contained. Comprehensible.

The first time he passed through the Gate, it was as though every little bit of knowledge in the world was being beamed into his mind. It had been agony, pure and simple, and yet exhaustion had brought no respite from the ceaseless pain.

Now, it was focused. There was structure to it. Where before he had learned just one part of Amestrian alchemy with what he had given up as a toll, more concepts that he had since heard of during their travels and yet never fully understood now entered his mind.

The Dragon's Pulse. Chi. Purification Arrays.

It was Xingese alkahestry, the counterpart of Amestrian alchemy that was founded upon the same underlying principles and yet entirely different. Where alchemy was scientific and rigorous, grounded in fact, alkahestry had always seemed whimsical, a concept that could never be explained in mere words, he now knew precisely just what it was at its core.

It was a lot less than the first time he had passed through the Gate, when it felt like knowledge of the entire world was being forced into his brain. These were the mere basics of alkahestry, a head-start , as Truth would call it. From here, they needed to experiment and reverse-engineer what they had seen Mei perform.

After what felt paradoxically both like infinity and barely a few seconds, the exit opened once more, and Edward felt himself collide painfully against the ground below.

Damned Truth. Couldn't he at least have given them a proper landing?

Ed shook his head, his blurred vision quickly clearing. Now was not the time for such thoughts. Gently, he moved his limbs, and it was only with a small amount of dismay that he realised both his right arm and left leg had returned to their automail forms.

Heh. Nice of Truth to repair those for him.

More importantly, though –

"Al?" he asked, quickly glancing around. "Are you here?"

His answer came just a few seconds later, when a second Gate opened, and sent a massive suit of armour hurtling down toward the ground.

"Al!" he shouted, running up toward his brother. "Are you alright?"

"Ed?" Al's voice came from his body of metal, as he slowly began pushing himself up. "Is that you?"

"Yeah," he said, relieved that at least Al seemed to be back to how he had previously been, even if he didn't have that armour with him. "Did you see it too?"

"Alkahestry?" Al asked, and Ed nodded. "Yeah," Al continued. "Mei told me about it before, but I never really understood just what she meant. Now, though…"

His voice trailed off, and Ed could understand why. Even now, knowing the fundamental basis of alkahestry that had just been shown to him, its ideas that paradoxically contradicted and complemented Amestrian alchemy still seemed absurd.

"You've still got everything intact?" Ed asked after a moment of silence, as he briefly gave his own body a quick once over. Limbs were still in place, and as far as he could tell he wasn't missing any of his internal organs.

"As much as can be expected," Al confirmed. "If anything, the pull on my soul from my original body within the gate seems to have weakened."

"Truth sure is uncharacteristically nice today, huh?" Ed commented dryly. "Giving us all this information with so little a toll – and then that thing he did with that creepy mantra that he spoke…"

"You felt that too?" Al whirled to face him from where he'd been loosening the joints in his armour. "It felt… it was warm, but with a sense of power and energy…"

"Yeah." Ed frowned. It couldn't be a coincidence that it was what he had felt when he had envisioned his life as energy for transmutation. And those words Truth had said… "This is just conjecture, but I think Truth transmuted our souls."

"What?"

"Think about it," Ed insisted. "Philosopher's Stones utilise souls to power transmutations. Back when Kimblee attacked me in Briggs, I transmuted my life force to make use of bio-alchemy to stop the bleeding. Truth said that he released our souls as well."

Experimentally, he entered the same state of mind he'd been in back when he had desperately tried to use whatever means he had at his disposal to fight on. He had seen himself as a living Philosopher's Stone, as yet another body of energy within the All that was the World. He drew upon that sensation, and –

"Brother!"

Al's sudden outburst divided his attention, and the warm heat that had quickly been building up faded.

"What is it, Al?" he asked, quickly glancing around. If there was a threat around…

"You were glowing!"

What?

Wait… it couldn't be a coincidence…

"Let me try that again," he said slowly, in as calm a manner as he could to ease Al's frantic panic. "Don't worry. I think I know what Truth did to us."

Again, he focused upon the same sensation…

"You did it again!" Al exclaimed, sounding amazed. "What are you doing, brother?"

Once could be written off as a coincidence. Reliability on repeated experimentation was support for his theory.

"I'm not entirely sure, but I think Truth somehow unlocked a way for us to transmute the energy of our souls more easily," Ed postulated, phrasing his words carefully. "If all alchemy relies on pathways and matrices, then what he did had to be the equivalent of drawing the Line to complete the transmission array."

Yes. That had to be it. Back in Briggs, it had taken every fibre of his being and every ounce of willpower he could muster just to accelerate his own healing, but now calling upon whatever this force was came with much greater ease.

"How do you do that?"

Al's armoured helmet didn't quite exactly allow for facial expression, but he could picture his brother gaping widely. Ed smirked for a moment at the mental image, before telling Al just what he had done.

"Picture your life as energy," he began saying. "The same as a Philosopher's Stone. Think of yourself as nothing more than a Stone made up of a single soul. Use that energy, and –"

Abruptly, the surface of Al's armour began to glow with a soft white light.

Okay. Now he understood just why Al had been so taken aback before.

"That's it, Al," he said. "You've got it!"

For a few moments, Al didn't speak, and Ed got the distinct impression that he was deep in thought.

"This must be how Homunculi get their resilience and strength," Al finally voiced his thoughts aloud, regarding Ed carefully. "They possess biological bodies, but are powered by Philosopher's Stones. If they can draw upon the Stones' power to regenerate themselves upon death…"

"…it wouldn't be too far-fetched to think that they use their power to gain their superhuman strength," Ed finished.

Certainly, there was no way that the sheer speed and destructive power King Bradley displayed could have been naturally obtained. Even Gluttony or Sloth couldn't have had the strength they possessed simply relying on their mass and biological makeup alone. He couldn't quite draw upon whatever this power was instinctively during a battle just yet, but knowing that he had the option available was comforting.

But if that was the case, if this was indeed soul transmutation, just what did Equivalent Exchange mean here?

How much was the energy of his soul worth?

"Is this what Truth meant?" he asked Al, trying to make some sense of his own thoughts. "If this really is the soul that we're talking about… could this 'Remnant' place have some form of bio-alchemy of their own that would let us get our bodies back?"

"It's possible, but –"

Abruptly, he fell silent, unmoving, and Ed knew just exactly why.

Something was wrong. There was something pricking at his senses, and after the many battles he'd been in, he'd be foolish to ignore that warning.

Carefully, he took more careful stock of his surroundings. They were in the middle of what seemed to be an open road, dense trees lining the path on either side. It seemed to be nearing evening, based on the position of the setting sun.

Then, the more practical side of him took over. Wooden fences – he didn't have much experience transmuting that for combat purposes – but large amounts of stone, earth and gravel of the path was freely available to him. Trace amounts of minerals within rocks could allow for limited deconstruction and reconstruction of metals as well, but not quite as much as he would have liked.

Then, without warning, they pounced out from the shadows of the trees.

His instincts cried a warning, and he tumbled aside. He felt the tips of something sharp ripping through his precious red cloak, thankfully avoiding any harm to himself.

"Brother!" Al cried out, and the tell-tale sounds of clapping and metal being reshaped told him that his brother had fashioned a weapon out from the traces of metal in the ground below.

Ed deftly somersaulted through the air, riding on the momentum of his lucky dodge to land safely some distance away. Now that he had some time to register just what had happened, he could see just what had attacked him.

what the hell?

"A homunculus?" he asked incredulously, closing the transmutation circuit as he brought his hands together. With practised eased, he reshaped the chrome, iron, and carbon on the tip of his automail arm, altering its structure into the wrist-blade he favoured.

The creature glared at them both warily, now that its alpha strike had failed. And a creature it was, for there was scarcely any other word to describe it.

Its physical form looked almost like a wolf, only larger than any that Ed had seen before. Its face was covered with a bone-white mask – or was that actual bone? – but it was its body that Ed recognised.

That inky black substance was one he'd seen many times over; first the black tendrils that came out from the Gate during his doomed attempt at human transmutation, then when he'd encountered the Homunculi, and most recently just minutes ago when Truth had dragged them both out through the Gate.

But this…

This was no homunculus.

"No," Al confirmed. "It's something… it's something else. It feels different. It…"

"It doesn't have a soul," Ed said, completing the thought that he knew Al was thinking.

He was no warrior from Xing or master of alkahestry, who could instinctually read the Dragon's Pulse and feel this mystical chi that he'd heard Ling, Fu, Lan Fan and Mei speak about, but even an amateur like himself occasionally felt the overwhelming presence of a homunculus. Now, shown the fundamentals of alkahestry by Truth, despite never before having practised this exotic form of alchemy he still knew that the being before him was entirely soulless.

And, being soulless, it didn't make even the slightest bit of sense.

How could a being without a soul move? How could it live?

And was it wrong to have to kill it? Could it even be killed?

He didn't have much more time for further thought, because it came lunging at him once more. At that point, instinct took over, and with another circulation of power and a slam of his palm upon the dirt below, columns of earth began to form from craters in the ground. They slammed into the soulless creature with great force, launching it away from them both to land some distance away with a resounding thud.

"Brother!"

"Right!"

They were both moving, each knowing just what the other was thinking. Their Teacher had drilled this into them, hard. Mustang's later tutelage (as much as he hated acknowledging the fact that the damned colonel taught him anything) only highlighted the importance of seizing the advantage during a battle.

Wrist-blade and transmuted spear pierced cleanly through the creature from either side. Just as quickly, both brothers leapt back, weapons held defensively, prepared for it to regenerate as homunculi did. It may not be a homunculus, being entirely soulless, but given that it seemed to be made of the same inky substance –

To their surprise, the creature only stirred for a brief moment, before disappearinginto black motes of nothingness.

"What the –" Ed gasped, his automail arm twitching at the unexpected development. "What is this?"

"It's like what happens after we cut off the parts of a homunculus from its body…"

Sure enough, within a few moments, there was no longer any sign of the creature, not even the true forms that Envy and Pride had reverted to once their Stones had been destroyed.

Just what the hell was that?

A low growl came out from the trees, followed quickly by another, and then another.

As one, both brothers clapped their hands, shaping the following transmutation before their minds registered the incoming attack.

Two walls of stone cut the incoming creatures off from where they came from either side of the road. Without wasting any time, Ed began processing the situation.

Four more of those creatures. Not extremely regenerative, but possessing a superhuman durability. Roughly a kilogram worth of various metals, a decent amount of silicon from sand, a load of inorganic matter and minerals, a sizable chunk of carbon, some water trapped within the soil –

Yeah, he could make do with those.

"I'm starting to understand why the toll he made us pay was so low," he commented dryly. "Damned Truth didn't mention soulless homunculi being the norm around here!"

With another application of alchemy, a spear of earth pierced into what would have been the flesh of a regular creature. It wasn't dead – could a soulless creature die? – but at least it seemed to be slowed down by wounds as any living being would be.

"Now's really not the time, brother!" Al chided, cleanly transmuting a wall of earth to fend off one of the creatures that tried to circle around to attack them.

"Heh." Ed allowed a final brief chuckle, before focusing his attention back on the four creatures attacking them. "Fine, then."

As far as he could tell, they were living, but not. They were even less of living beings than the failed products of human transmutations, since those at least had souls.

These monsters?

These he could fight without hesitation.

"Come at me, then!" he taunted, pirouetting to dodge the closing jaws of one of his assailants.

Another quick formulation of his desired structure, and a series of cannons composed of sand that launched projectiles of rock was formed, firing their payloads at the creatures. One fell, disappearing into nothingness, and two more were injured.

Compared to homunculi, these were child's play.

Within moments, the only evidence of a fight having taken place were the pillars of earth rising from the ground, the hands of metal and stone that reached and grabbed at the creatures, and shattered projectiles that had been broken from impacting against their foes. Another few transmutations, and not even that remained, beyond the slightly unnatural borders within the dirt that marked the use of alchemy.

"They're not homunculi, that's for sure," Ed said, reverting his automail arm to its original form and hiding it under the long sleeves of his cloak.

"Yeah," Al agreed, but still seemed troubled, and Ed couldn't blame him. Aside from the fact that they broke every known law of alchemy – where did their mass go when they disappeared, for one? – there was the matter of whether or not they were living creatures. "Brother…"

"I know," he assured Al. "I don't like it either, but until we find out more about this world and whatever the hell those things were, we've got to treat them as enemies. These aren't like the chimeras or even homunculi that we're used to."

He'd become close friends with Greed over their travels – he was still furious and grieving at how Greed had sacrificed himself so they could take down Father – but these creatures lacked any form of personality or individuality, furthering their hypothesis that they had no soul.

"Right," Al affirmed, but didn't sound his usual spirited self. "Let's just – let's just try and find somewhere we can get some answers."

"Yeah. Plus, I'm willing to bet that these things tie in somehow with the method Truth hinted to us about how we can get our bodies back."

Knowing how that damned bastard worked, Ed was under no illusion that these were probably not the only enemies they'd be facing. Dusk would soon be falling, and he really didn't want to be caught off-guard again by anymore of these things.

"Let's hurry," Ed said, beckoning over to his brother. "Hopefully, that'll be the last we see of –"

A burst of thunder split through the air, followed quickly by several more. In the distance, the distinctive sight of towering flames appeared out of nothingness. Clouds swirled overhead, even though just moments before the skies as far as the eye could see had been entirely clear.

"…me and my big mouth," he groaned, then exchanged nods with Al. "Let's hurry!"

As they sprinted toward where the fighting was – for what else could it be? – he privately hoped that all this wasn't the norm for this world.

-o-o-o-