Disclaimer: I only wish I owned the rights to Edward, Roy Mustang, and Fullmetal Alchemist Brotherhood. If I did, it would have been yaoi. Yeah, definitely yaoi.

Plot Synopsis: The world doesn't end with a transmutation, it ends with a Flame. AU, RoyxEd. Canon divergence, Episode 53, Flame of Vengeance.

Author's Note: I was blown away the first time I saw Brotherhood. It completely made up for my disappointment with what was basically the last half (and the movie) of the original anime. This is based on Brotherhood - which made me respect Mustang's character a hellova lot more! - but I'll be borrowing from the manga and FMA as needed (remember, AU). It's my first venture into the FMA world - and unbeta'd - so please, be kind=).

The Fires Within

Chapter 1

The tunnel stretched out before them, long and dark as it arched and curved towards the very heart of Central. Their footsteps tapped out an uneven staccato as they walked, their voices hushed with something that greatly resembled fear. Most of them knew what awaited them; he, Scar and Mei had already found their way into the Homunculi lair once. Jerso and Zampano had only their descriptions of Father and his power to go by, but even they could sense the evil that seemed to permeate this dark place. It was a heavy feeling that suffused the air, leaving their stomachs tied in knots and their hearts beating faster in the chests. Intangible, but undeniable all the same.

Edward Elric did his best to ignore the unsettling sensation as he looked over his shoulder for the umpteenth. He could hear the occasional boom of Colonel Mustang's flame alchemy, always followed by cries of pain and screams of frustration, and he felt a fleeting sense of pity for Envy. The homunculus had no idea what kind of hell he'd unleashed on himself when he had confessed to killing Brigadier-General Hughes, but Edward was willing to bet that he was getting a clue now. The Flame Alchemist wasn't a man to be taken lightly, and with Envy's superiority complex in high gear, it sounded like he was learning his lesson the hard way.

But Edward had to admit that he was worried. In all the years that he'd known Mustang, he had never seen him like that. The Colonel might be a smug, smirking, manipulative bastard of a commanding officer, but he was not a cruel man. And behind closed doors, he'd shown himself to be surprisingly. . .gentle, almost kind to those he cared for. It was those times, when they were alone and the rest of the world fell away, that Edward loved Roy Mustang the most.

Yet, the darkness he'd seen in Mustang's eyes when he'd looked at Envy had been downright. . .scary. There had been no empathy in those exotic black orbs, none of the compassion that Edward was so used to seeing. Oh, the arrogance was there – it was always there – but the almost sadistic kind of glee buried in their dark depths had him second-guessing his decision to continue on. Yes, Father and the other Homunculi had to be stopped, but if they lost Roy – if he lost Roy – Edward would never forgive himself.

They came to another bundle of pipes, this one larger than the others, and he listened almost absently to the others as they began to climb over it. Rancid chi, fear, and Father. Nothing he didn't already know. He stopped and half-turned, twisting to look down the corridor behind him. The noise had stopped, and that had him more worried than Envy's screams had. He had no way of knowing if Mustang was still alive, or if Envy had somehow managed to overcome him.

What the fuck would he do if Roy died?

His hands curled into fists as he stared blindly at the ground, and he knew that he couldn't go on without knowing. "Scar, I need to talk to you."

The Ishvalan man paused in his ascent of the pipes, slanting an unreadable glance back his way. "It's about the Flame Alchemist, isn't it?"

Edward made a small, involuntary sound – of denial, of fear, of confirmation, he didn't know which – as he raised his head, and something in Scar's scarlet eyes softened. God, was he that easy to read?

"It wasn't that long ago that I was a monster. I understand the burning desire for revenge all too well." The other man paused, his unusual eyes taking on an inward cast, and Edward wondered just what he was seeing. "The way he's headed, he'll destroy himself in the flames of hatred, and it's doubtful that he will ever recover."

As thought to emphasize his words, flames flared up at the end of the hallway, filling the corridor with smoke and the sickening stench of burning flesh. Edward whirled around, his golden eyes widening as the sound of Envy's screams came to him again, because this time it was different. There was no arrogance in those horrific sounds, none of the overconfidence that was the homunculus' trademark. Instead, there was only one long howl utter and complete physical agony.

"Goddamn it, he's going to kill him!" Edward swung away and took off at a run. "I've got to stop him! Tell the others I'll catch up!"

He didn't hear the other man's grunt of displeasure, but he heard the footfalls that fell beside him clearly enough. "You don't have to come with me," he snapped, already breathless from the pace he'd set. It wasn't that he was out of shape – he was only sixteen, for crying out loud! – and Roy had told him that he was nearly at the peak of his physical prowess. No, he was scared shitless that his boyfriend was about to do something stupid and fuck the rest of his life up!

Scar merely grunted again and kept pace with him, and Edward rolled his eyes. The other man seemed able to talk to Al and even Winry easily enough. What was it about him that made the Ishvalan either clam up, or choose his words so carefully that Ed wanted to crack his head open just to get a straight answer?

"You believe in him," Edward was startled by the unexpected question, "in your Flame Alchemist?"

"Fuck yeah, I do!" he answered emphatically. "Mustang's going to lead this hellhole of a country to better things, Scar. He's going to be the best Fuhrer Amestris has ever had."

He felt more than saw the Ishvalan's gaze touch on him as they ran. "Then, let us hope that we reach him in time, Fullmetal Alchemist."

Edward scowled at the formality. He didn't know why Scar refused to call any of them by their given names, but it pissed him off to no end. He wasn't just a State Alchemist, damn it! He was a living, breathing person, one who was trying to save his country from a corrupt and literally inhuman government. That should fucking count for something, shouldn't it?

They rounded a corner and were nearly incarnated as a wall of fire came billowing towards them. Edward's feet skidded out from under him as he hit the ground, throwing his arms over his face to protect himself. Once the flames had receded, he looked over to see Scar slowly lowering his own arms. The cuffs of his jacket had been singed, and he was wearing a troubled expression as he gazed down the corridor, but he still had his eyebrows, so Edward figured he was good.

He didn't bother to check himself for wounds. Half his limbs were automail, and if he'd burned the other half he'd fucking know it. Right now, all he wanted to do was get to Mustang before he did something that would haunt him for the rest of his fucking life. He was carrying around enough shit from Ishval as it was. He didn't any more "sins" to weigh him down, not when he had the future of an entire country to carry on his shoulders.

But, God, the stench! Edward brought his arm up and covered his nose with his jacket sleeve, reminding himself to not to breathe through his nose. It helped – a little – but it didn't do anything for the goddamned sounds. All he could hear were the snaps from Roy's ignition gloves, echoing and rebounding as they bounced off the stone walls, making the explosive nature of his lover's special brand of alchemy seem all the more devastating. Roy was using his flames to their full, terrifying potential, as those horrifyingly real screams of anguish coming from Envy could attest.

And then, it all just stopped. The explosions, the screams, everything. All that was left was a silence so complete that it turned Edward's blood cold with its implications. He closed his eyes and offered up a prayer – to God, to The Gate, to whatever uncaring deity that might be bored enough to listen – and forced himself to keep walking. For the first time since he was eleven years old, he was genuinely afraid. He didn't know what was waiting for him around the next corner, and he knew that his future – his life – depended on what he was about to see. If Roy was dead. . .

He shuddered violently and banished the thought as quickly as it had formed. Roy Mustang was a tough bastard. He'd survived Ishval, he'd survive this too. They would defeat Father and the Homunculi, and Mustang would fix their broken country.

And Edward would be with him every step of the way.

He felt a weight on his shoulder and jumped, surprised to see that they were nearly at the end of the tunnel. He looked up to see Scar gazing at him with more emotion than he'd ever seen the man display. It was pity – or something close to it – stamped into his craggy features, and Edward's gut coiled warningly in response.

"Your Flame Alchemist, Fullmetal."

He jerked his silver head to the left, and Edward followed the motion with trepidation. There he was, standing in the middle of the fire-blackened corridor, his silken ebony hair fluttering in the breeze that his own alchemy had created. He was still wearing that expression, the one which had disturbed Edward from the very beginning. It had been enough to send him scrambling back here to save the man he loved from himself, and it was enough to keep him rooted to the spot now that he'd finally reached him.

Roy had one boot pressed threateningly on what was left of Envy, and even as Edward watched he began to press down, intent on destroying the diminutive lizard-like creature that was Envy's true form. The homunculus was begging for his life, but there was no mercy in Roy's eyes, and very little humanity. Edward knew that he stood on the cusp of a very unstable precipice, and all it would take was one tiny push, and it would be all over.

A movement behind Mustang caught Edward's attention, a flash of fair hair and russet eyes, and he realized that Hawkeye had beaten him here. She lay sprawled on the ground just beyond him, blood pouring from a gash in her left shoulder, her eyes wide as she just stared at Mustang. There was something close to horror in those expressive eyes, and that was when Edward realized that not even she, who'd been closer to Mustang than anyone else before him, had ever seen this side of him before.

It was a personal epiphany. Edward had always assumed – jealously – that she and Mustang were lovers. Hell, everyone had, especially since Roy's response when asked was always a very ambiguous, "I refuse to dignify such a base rumor with a response,". Edward had always taken it as an evasion, one that had caused alot of problems between them. Roy had accused him of not trusting him, and in return, Edward had accused him of being a duplicitous bastard.

But now, he finally saw the truth, and he was ashamed. Riza Hawkeye had never been intimate with Roy Mustang. She'd hadn't held him in the dead of night, when the atrocities he'd committed in the name of his government left him steeped in guilt and covered in imaginary blood. She didn't know the shame that Roy held deep in his heart, she'd never seen the despair that had made this rage possible. She cared about Mustang – probably even loved him – but she sure as hell didn't know him if she hadn't been expecting something like this.

"So, this is your true form, then." Those deep onyx eyes with their catlike tilt at the corners narrowed ever so slightly on Envy, and his smooth voice trembled with the force of his fury. "You're. . .ugly."

Edward flinched at that. Mustang, ever the master manipulator, playing on what was probably the only insecurity that the shape-shifting homunculus had. Envy wore the human forms the way Mustang wore his uniform, with pride and unmatched arrogance. Edward had never really given it much thought, but he could see that Mustang had, and that he was using his whip-like intelligence to fuck with his victim's head.

He absolutely hated thinking of Envy as a victim – especially after all the shit he'd pulled – but Roy had reduced the homunculus to a quivering, sniveling mound of unnatural green flesh. Truly pitiful sounds escaped the defeated monster, muffled sobs and terrified whimpers. He was well and truly afraid of what he'd set free, Edward couldn't blame him for his fear. Roy was so close to the edge that even he could feel it, and after the destruction of his human form, Edward didn't doubt that Envy could too.

But Edward knew something that Envy didn't, something that even Lieutenant Hawkeye hadn't quite figured out yet. Roy Mustang wasn't a killer. No matter what they – or even Roy himself - believed, the hate-filled man standing before them was not who Mustang really was. If it were, he would've destroyed himself long before this.

But it was all Edward could do to keep his mouth shut as Mustang continued to taunt the defeated homunculus. He wanted to rush out there and yank the homunculus away from the older man, to smack Mustang upside his attractive head and demand to know what he thought he was doing. But like he'd told Scar, he trusted Roy. He trusted his bastard Colonel more than he ever had anyone else – except, maybe, for Al – and he refused to let himself doubt him. Roy wouldn't let himself become a monster. He would pull himself back from the edge, and he'd do it without help from anyone.

"Envy means jealousy." Mustang paused – ever the showman, creepy though the show was – and it almost seemed like he was enjoying Envy's pathetic display. "That's what your name means, right?"

He pressed his foot down just a little harder, and Edward winced at the high-pitched squeal of fear that rent the smoky air. "I get it."

The deep, beautiful silk of Roy's voice was little more than a bestial growl, roughened by hate and resonating with the grief that had been eating at him since Hughes' death, and Edward felt the first traitorous kernel of doubt bloom in his heart. He silently urged the man to snap out of it, to come back to himself before it went too far. If he was wrong about Mustang, it would fall to him to stop him. If he had to fight the man he loved because he couldn't bring himself back from the brink of oblivion. . .

Edward swallowed hard and stepped forward, intent on stopping this travesty of justice before Mustang had a chance to fail, when he the pressure on his left shoulder increase. He craned his head up and to the left, blinking with surprise. He hadn't realized that Scar was still touching him, so immersed was he in his fear for Roy. The other man's hand tightened, he knew that Scar was doing much more than attempting to offer comfort. He was restraining him.

"Let me go. I have to stop him." His voice was raw with emotion, his frantic golden gaze returning to his lover as he began to strain against Scar's hold. "Damn it, Scar, he's losing himself!"

Scar only shook his silver head negatively, his eyes never leaving the ghastly scene before them. Envy, begging for his life, and Roy Mustang, determined to take it. "It is too late, my friend. He will either give in to the beast, or rise above its need for revenge. Only he can make that decision, now."

"Please, don't. . ." Envy's voice was little more than a feeble wobble in the ghastly silence. "No, don't!"

A graceful hand, clad in obscenely pristine white cloth, was splayed menacingly before the defeated homunculus, and Edward felt a jolt of pure terror. Roy wasn't going to come back to himself. He wasn't going to stop. He was going to kill Envy, and murder his soul in the process!

"And jealousy is an ugly thing."

"Noooo!" Envy began to struggle in earnest, screaming and wailing as he thrashed beneath the rubber sole of Roy's boot. "I don't wanna to die!"

Mustang lifted his hand with agonizing slowness, the ignition cloth of his gloves rasping and sparking as he rubbed his thumb and forefingers together. His intention was all too clear, and Edward had only one thought: to get to Roy before he went through with this fucking madness.

"I'm not giving you a choice!" Mustang was beautiful in his rage, both stunningly breathtaking and deceptively righteous in his wrath, and Edward's breath caught in involuntary appreciation. "NOW BURN IN HELL!"

The unmistakable sound of a bullet being chambered stopped Edward dead in his tracks. It echoed as loudly as a gunshot through the narrow space, and he saw that Hawkeye had finally come to her senses. She had her revolver trained on the Mustang's head, her expression one of grim determination, and Edward slumped against Scar in his relief. Hawkeye had always been Mustang's conscience. If there was anyone he would listen to right now, it would be her.

Deep pools of endless black slid to Mustang's left, locking on the woman who'd served him for years than Edward had been alive. They were the only part of his body to move, and Edward had to admit that it was a fucking creepy effect. "And what do you think you're doing?"

Hawkeye's own eyes narrowed at the menace in his own. "That's enough, Colonel," she told him in a stern, no-nonsense voice. "I'll deal with him from here."

Mustang's gaze left hers, focusing on Envy once more. A muscle ticked in his jaw as he spoke. "He's as good as finished," he forced through clenched teeth. "Lower your weapon."

She lifted her chin bravely. "I can't obey that order. Put your hand down!"

The faintest of movements was all it to took, and blue lightning sparked along the length of his hand. "Damn it!" he yelled impotently, incensed by her interference. "I won't ask again!"

He curled his hand, the muscles in his arm and shoulders bunching in preparation to strike. Alchemic energy danced around the white glove with its red-stitched array, power literally crawling over his trembling form, bathing his entire body in blue-tinged light, and then he snapped.

Edward knew then that Scar had been right. It was too late. They had lost him – he had lost him.

It was his last conscious thought before instinct took over. He elbowed Scar in the stomach, shoved him away, and slapped his hands together in the same motion. The resulting clap was sharp as it reverberated through the tunnel, and before it faded he was crouched on the ground, his hands pressed to the blackened stone as his own alchemy surged to life. He directed the energy along the length of the tunnel floor, brilliant streaks of cerulean light racing along the ground towards Mustang and his captive. Flat-edged chunks of weathered stone to grew out of the tunnel floor, row after row overlapping each other like dominoes falling in reverse.

Edward's only thought was to rescue Envy from the sphere of fire that was consuming him, to get the homunculus away from Mustang before he died. He didn't care if Envy survived the Promised Day or not, he just didn't want Roy to be the one to murder him. Because that's just what it would be. Not justice for Brigadier-General Hughes, not vengeance for a fallen friend, but murder plain and simple, and Roy was better than that.

But instead of Edward's alchemy dislodging Mustang's foot and launching the homunculus into his waiting hands as planned, Mustang himself did something that turned the tables and caused his entire plan to go up in smoke.

Time itself seemed to grind to a halt as Mustang slowly, deliberately, turned to face him. He looked straight at Edward, rage and pain and betrayal distorting his handsome, maddened features, and – oh God, Edward had never been so terrified in his life! Then his infuriated expression changed, cruel lines and sharp plains blending into something softer, more intimate. He extended his arm, his white-clad fingers curling slightly before splaying wide, a loving invitation that sent relief careening through Edward's entire being.

He hadn't lost him!

The knot of terror in his chest unraveled as Edward shifted to his knees, his own lips curving into tremulous smile as reaching out to take his hand. Roy murmured his title, "Fullmetal," just like he always did, the smooth silk of his voice sweeping over Edward like a physical caress, a darkly sensual sound reminiscent of darkened bedrooms and rustling sheets and unrelenting physical pleasure. Edward shivered as the tips of his gloved fingertips met Roy's, gliding almost teasing over the other man's, his trust fueled by his love for the man who had shaped so much of his young life.

And then Mustang began to laugh. Insanity tinged the rich, wholly beloved sound, warping into something dark and twisted and malevolent. Edward recoiled, snatching his hand away and scooting backwards, but it was too late. A thunderclap rent the smoky air, sparks flying from between gloved fingertips, and the world began to burn.

Time snapped back into motion as a ball of alchemic flame shot towards him. In desperation, Edward reacted, hastily clapping his hands and slamming them to the broken ground. Even as he watched his own energy rush towards Mustang's, he wondered if it wouldn't be enough. Would his alchemy be strong enough to overpower Roy's, or would they all be destroyed in the alchemical backlash?

He heard Envy scream, the loud rattling sound tolling the homunculus' death knell. It was echoed by Edward as his power met Mustang's and rebounded. He was thrown to the ground, his entire body seizing as his muscles spasmed, his every sense overloaded as he was engulfed in his own alchemical storm. He couldn't move, he couldn't breathe. All the oxygen had been sucked out of the air, greedily devoured by two very different kinds of alchemy.

Dimly, he heard another snap, but he was beyond caring. His world had been reduced to shades of pain, and it was all he could do keep himself conscious. He knew that in a few moments, it wouldn't matter. He would be dead, and all that would remain was the monster that Roy had made of himself.

He was almost glad he wouldn't live to see it.

A body appeared above him, large and heavily-muscled, its tattooed arms reaching for him as it blocked out the light. Edward licked his lips and tried to speak, his entire body jerking as it fought to draw the breath necessary for speech, but it was so hot and there was no air. He managed to lift his arms, his hands latching onto the other's shoulders – damn it, he should know who those tattoos belonged to! – and clung to them with all of his waning strength.

The man above hunched closer, grasping Edward's wrists as he wrenched his hands away, shoving them back down to the scorched ground. His hair had been completely burned away, and Edward watched with horror as flames licked greedily at his tanned, scarred face. "From one brother to another," the man rasped as his arms began to blow with unearthly light, "take his gift and use it well, Edward Elric."

The light grew stronger in brilliance, glowing so brightly that it eclipsed the sight of the man who was burning alive above him. Edward squeezed his eyes closed as agony suffused his body, his arms burning with a different kind of fire, and then – mercifully – the world went black.