Disclaimer: I do not own Homestuck, Andrew Hussie does. I do not own Fullmetal Alchemist either. I would've thought that the website name would have told you as much, but apparently not, if you're reading this disclaimer.
Introduction: You are about to read a Fullmetal Alchemist/Homestuck Crossover. This takes place sometime after the Elric brothers find out the true nature of the Philosopher's stone, and after the end of Homestuck: Act 5. The estimate length of this crossover will be 4-5 chapters. Possibly more, but I don't think so. Rated T for language and graphic descriptions of violence.
Amendment 1 (6/21/12): This actually would be a sort of FMA AU where after the collapse of laboratory Five, Ed and Al don't decide to visit Izumi, and decide that the lab was a dead end. Hughes still discovered about the nation-wide transmutation circle, but due to circumstances I won't elaborate on right now, Envy's attempt to kill him met with failure.
John shut the door to the reactor core of the Prospitian Battleship. Three years of no maintenance had left the ship's main power source heavily degraded, not to mention the core's containment system. Davesprite had suggested that they bring up the Battleship to fully operational status, in preparation to fight Jack Noir. After a quick crash course on reactor repair by one of the surviving Prospitian mechanics, John was able to affect a quick-fix to the reactor's containment systems, ensuring a safe, steady supply of power to the ship's weapon systems.
Tightening the last deadbolt on the door, John cringed as pain racked his body again for the seventh time. He had been assured that such a limited exposure time to the ship's power source would not impart any lasting effects on him, and even if he did manage to receive a lethal dosage of the stuff, he'd just come back to life. Dying from maintenance was neither just nor heroic; it was just lame.
John scaled the ladder out into the main maintenance corridor, and after taking a few more turns, stepped out onto the gilded deck. The elegant craft sailed at light-speed through a myriad of green, blue, white, and other unidentifiable colors. As John made his way to the ship's bridge tower, the gun emplacement around him emerged from their housing beneath the deck, humming as they spun up their systems.
"Gah!" Jade nearly jumped when John entered the room, "Oh, John, it's just you."
"Of course it's me," John snickered, "Who else were you expecting?"
"Davesprite maybe," Jade rubbed the back of her neck, "I guess I'm just a little nervous. It was so easy talking about how we were gonna fight Jack a year ago, when today seemed so far off. Now that we actually have to go fight, I'm a bit high-strung."
John and Jade turned to stare out the bridge windows, at the giant, four-paneled window looming large in their field of vision. The screens around the bridge's viewport lit up, displaying that the ship was now at full-operational capacity. Dials spun and buttons lit up, all seemingly in anticipation of the oncoming fight.
"All the non-combatant personnel are secured planet-side Captain Harley!" John mockingly saluted.
Jade giggled in reply, "Alright then, Officer Egbert, to battle stations!"
Then the window turned off.
The window through which they could see the new session, their only escape, was turned off. They were now hurtling towards a dead hunk of metal and glass at light-speed.
John gasped as Jade yelled, "What happened?"
"I don't know!" John screamed, "It's just… black!"
Jade quickly checked the countdown clock which they rigged up almost three years ago, it's minute number down to one digit, and the seconds were flying past. "John, put the ship into reverse!" Jade commanded as she summoned her space powers, attempting to slow down the ship, but without access to the power of the Green Sun, which was what fueled the initial push.
John quickly flicked switches and pulled levers, and the Prospitian ship directed all its thrust towards the fourth wall, engines screaming in protest and futility. John stared dejectedly at the steadily nearing wall.
"Jade," he muttered, "I don't think we're going to make it."
"No! Work, Damn it!" Jade spat, green lightning arcing off of her body and the ship itself as she attempted to bring the ship to a standstill. John lifted his arms as well, and soon, hurricane-force winds were assisting in the ship's deceleration. It still wasn't enough.
The jade glare within the bridge intensified, and a scream was wrenched from Jade as she drew upon her own life to fuel her God powers. The only thought in her mind was to escape.
Just before the prow of the ship kissed the window, a tear was opened in the fabric between dimensions, and the Battleship, carrying two ecto-siblings, as well as the remnants from a failed session were sucked into the rift, which closed in an instant, leaving behind nothing to suggest that anybody had been there, save for the rapidly fading breeze.
Edward Elric, Fullmetal Alchemist, dog of the Amestrian military, was relaxing in Central, a sandwich in his left hand. He was sitting lazily on a bench in one of the many squares spread throughout the city itself. The eldest Elric brother was staring blankly at the sky, his mind superimposing alchemical equations and formulas over the slowly moving clouds, when a far off glint caught his eye.
Ed shielded his eyes from the sun with his right hand, trying to get a better look at the anomaly high in the sky. It was a dot at first, but then began to get bigger. It was gold, and resembled one of those naval combat vehicles that he had heard about from far-off lands. Green lightning was arcing off of it and it was surrounded by a maelstrom of wind that was dragging the very clouds with it. Not to mention that it appeared to be streaking towards Ed at phenomenal speeds.
Several thoughts raced through the Fullmetal Alchemist's head as the oncoming craft grew closer. What the hell was that thing? Was is some kind of weapon from a neighboring country? That wouldn't make sense though, would it? This thing was coming from the goddamn SKY. That lightning, it couldn't be natural, after all, who heard of green lightning? Then again, who ever heard of red lightning, but Philosopher's stones gave off red alchemical reactions. Was that thing somehow using a type of alchemy that gave off green lightning?
This is certainly worth investigating, Edward thought, then grimly added, if I don't die first. After a moment's thought, Edward concluded that there was no way to stop the hurtling projectile. The force of impact would probably wipe Central off the face of the map. Nothing he could transmute would negate the tremendous kinetic force of the craft. Even if he violated Equivalent Exchange, and had to give up more to that goddamned Truth, he doubted that would be enough. Then again, he might not need to, because… was that thing actually slowing down?
Indeed it was, as Edward and several hundred horrified Amestrians looked on. The wind was gradually reducing the speed of the golden Battleship. Ed could make out countless, car-sized nozzles jutting out from opened panels all over the front of the ship's hull. They spat blue fire, the exhaust fumes being blown back and streaking across the pristine golden hull, leaving burn marks in wavy patterns. An ear-shattering boom rumbled throughout Central as the Battleship dropped below the speed of sound. All the glass in Central shattered, and the noise was heard out in the Amestrian countryside.
"There's no way that thing could have decelerated that fast," Edward breathed, "Unless it has a hidden propulsion system. Or just maybe," he grinned, "it has a way of bypassing Equivalent Exchange." The Fullmetal Alchemist was convinced that there was some sort of Philosopher's stone onboard that craft, or at the very least, an Alchemic amplifier. Or just maybe it was an entirely new way to pay for Equivalent Exchange. Either way, this was very much his business.
The Battleship came to an almost sudden stop just a meter off the ground. The nozzles on the hull spewed blue flame across the pavement, melting the thankfully empty plaza into molten slag. Ed transmuted a platform, which raised him up to roof level, and he vaulted off of it onto an empty roof just as the platform destabilized from the ship's exhaust. Gale force winds whipped throughout Central, tearing off ceiling tiles and anything not bolted down or sufficiently heavy enough. The Fullmetal Alchemist beheld the golden ship as its nose began to climb, and the entire craft leveled out. It maneuvered to a short distance away, and settled itself down on top of several houses, whose occupants quickly and wisely evacuated before they could be crushed like bugs.
As it moved, Ed finished off his sandwich, deconstructed the wrapper, and transmuted various roof-to-roof bridges as he made his way to the ship's landing site. Just from a glance, he could tell that the ship was made with a militaristic purpose in mind. Albeit a military with heavy emphasis on aesthetics, but there was no mistaking those weapon emplacements, even though he did not recognize the weapons themselves.
Street side, soldiers were already making their way towards the foreign object. Edward just hoped he could make it before Mustang. There was no way Colonel Bastard didn't notice this. However, along with the Fullmetal Alchemist, every Amestrian soldier and official was converging on the craft.