A/N: Hey everyone, Skye Blade here again with a very different approach to the Attack on Titan universe. This one is more akin to a crossover of AoT and Knights of Sidonia. This is just a little one-shot of the AU I imagined, featuring Erwin Smith as the only canon character named. Also, this was something I wrote to practice combat scenes where the combat is done through a machine, rather than a persons body. Please critique it. I've been trying to get a good writing setup for combat via machines, and I still feel like this setup doesn't quite work very well.

Anyway, that's enough of an Author's Note. Please enjoy!

Project: Titan Mech

It's been an ongoing war for as long as history can remember. Everyone is raised knowing it, everyone lives in it, and everyone dies in it. It's not a war that can be lost, because there is no surrendering to these monsters. Not for humanity. Losing means extinction. Sergeant Erwin Smith knew what defeat meant, and his death would mean little if he lost it in a skirmish… most of the soldiers who had died knew that, too.

A warning siren blared in the hangar bay, a scramble alert. Erwin was already in his machine, the X-3 Raptor. A machine that stood just a little taller than one story in Combat Mode. Bipedal in design with the ability to shift between Combat and Travel modes. Combat mode featured an extremely agile bipedal robot with arms to suit that of a human, but instead of a torso, attaches to a cockpit similar to a snakes head. Its agility came from its booster pack, which allowed it to fly, and quickly maneuver in and out of cover. Travel mode, while ugly, is highly effective. The cockpit tilts up and pulls the limbs to a rigid position so I looks like a warhead, and using small, aerodynamic surfaces on the arms and legs to allow for some maneuverability. The modes can be traveled between almost instantly, allowing high maneuverability, and speed.

The weapon of choice for this machine: The R-6 "Boomer", a Vulcan cannon that has a slowed rate of fire, and fires a round nicknamed "Titan Gibber" for its explosive properties.

Erwin closed his Raptors cockpit, and attached his Neural helmet, and proceeded to "Dive" into the machine. When the processes completed, he was in control of the machine as if it were his own body. Everything checked out, and he mobilized towards the catapult. "Erwin here, ready for launch."

"Granted."

It was good to see the officers that were cozily tucked in HQ were as informative as ever. "I need details, Ashley. What is my squad up against?"

"Multiple contacts, looks like a wandering group. They've spotted us and engaged our perimeter automated defenses."

Erwin rolled his eyes, "I wouldn't be scrambling if that weren't the case. What class hostiles are we up against?"

"Group size is fifteen titans. Twelve are ten meters in size, three are fifteen in size."

Erwin translated the officers words into their technical terms, more for his own sake than the other personnel. "Twelve Class-B's, and three Class-A's. Any Unique Variants?"

"None reported, though be on the lookout."

Erwin transformed his X-3 into travel mode as the catapult doors opened up. It was odd, under normal circumstances he would've been out the door as soon as he was granted permission… though he brushed it aside. It wasn't his job to ponder their base's maintenance. He flicked his visor down, "Will do. Omega one, launching!"

Erwin was catapulted out of the hangar, his fire team following in rapid succession. The computer linked them together, showing each X-3 and their respective pilots in a 2D representation on his HUD. Erwin opened the communication channel, and spoke what little battle plan he had, "Standard defense. Keep the titans from breaching the perimeter, and getting to our town. I don't need to explain what will happen if they do."

His team all confirmed, and as they approached the perimeter, the whole team swapped to Combat mode. Their altitude steadily dropped like bricks in freefall, and smashed into the devastated earth. The onboard computer, Battle Broadcaster, (nicknamed Bitchin' Betty, or just Betty) spoke, "Contacts within visual range. Beginning combat mode." Erwin wasted no time, and started on the hostile titans. The automated defenses had managed to take down four of the Class-B's, but were heavily damaged, or out of ammo. Erwin targeted the nearest Class-B, and the large, mutated mess of mimicked flesh started lumbering towards him. His R-6 revved up as the Aim Assist produced a firing solution. Erwin pulled the joysticks trigger, and fired. The large booming from the shells would have been deafening, had he been outside the Raptor. The R-6 overheated, and began cooling, but not after it expended forty shells from his ammo storage (designed to appear like a box mounted on the shoulder.)

Probably about half of his initial attack hit the target, though at his range, none of them did enough damage to halt, or even slow the titan. If anything, he just pissed it off. The titan sped up, the wounds he caused already sealing up. The titan was hunched, and moving at a slight jog now. The monstrosity got closer, and made the mistake of getting within optimal firing distance. "Weapon cooldown complete." Betty informed him. The R-6 revved up, and expelled another 40 shell barrage.

Almost all of his shells hit target, and most of them pierced deeply into the titans body, to the point where it lifted its left leg to take another step, calve didn't move with the thigh, and the titan toppled over. Though it wasn't quite dead. Crippled, but it would get up in thirty seconds if he didn't finish the job. Erwin activated his booster pack and dashed to point blank range, the titan swiped at him once trying to buy itself time. A futile effort as Erwin was at point blank range. "Weapon cooldown complete."

The shells caked his machine in titan blood, and the full barrage split the titan straight to its lower back, and it died, unable to regenerate fast enough. Over a dozen pieces of it scattered in an area of five meters, hitting the ground like large rocks.

Erwin dashed away from the corpse, checking for his fire team. Each of them had managed to take down their own class-B's, leaving them with four more, and the additional Class-A's. However, they faced the real challenge of combating the monsters. They took four down quickly because of they had surprise on their side. The remaining seven knew where they were, and to make it worse, the three Class-A's were already moving in. "Team, spread out and pick a target! Do not let the Class-A's get close!"

Erwin targeted the next Class-B, which had focused on one of his teammates. The bayonet from his R-6 jutted out, "Bayonet activated, toggling weapon control to pilot." He dashed towards the enemy from behind, and converted the momentum from the dash to a leap. He came down on the Class-B's rear skull. The heavy hitting strike not only pierced into the skull, but also split the head wide open, and fracturing the neck all the way to the start of the spine. Erwin fired one shell to free his weapon, then boosted away, and unloaded a full barrage into the titan as it fell over. The R-6 overheated, and the titan was cleanly cut in two straight down the middle. Unable to regenerate, it went limp.

Erwin landed and saw Omega 3 backing away from a Class-B, and unfortunately, towards a Class-A. "Omega 3, dash towards me, now!"

"Why?" Was his response, though the Class-A didn't give Erwin the chance to answer the soldiers question. There was a swift hand that had picked up the soldier, "Oh god, oh god! Help me!" The Class-A had picked up the Raptor, an despite pumping his a full barrage into the head of the Class-A at near point blank, and destroyed everything above the lower jaw. The titan still proceeded to bring him up to what would've been eye level, tongue flailing about as it tried to swallow. Though the titan had no interest in trying to eat the machine, or pilot. "Kill it! Kill it! For fucks sake, HELP ME!"

"Omega 3, bail out! Eject! Eject!"

Even from his distance he saw the pilot reach for the handle, and pull it. The canopy flew off, and the pilot shot out with his seat. It was a clean eject, but the titan was quicker. The overhead palm that was going to destroy the Raptor and pilot together, instead turned the pilot into a blood stain on its palm, and then crushed the Raptor.

They were now down a pilot, with four more titans to go. All three Class-A's still alive. "Omega one to base, we need reinforcement."

"Omega one, our launch bay is down. There are no reinforcements available at this time."

"Requesting a Titan Buster, then!"

"Request denied. It's only three Class-A's. We will have reinforcements available in two minutes, hold them off until then."

"God damnit!" Erwin looked up at the Class-A which just finished killing one of his pilots. The head already developed its muscle structure, and had discarded the Raptor that it smashed into a flat sheet. The left eye rolled into socket.

"Sarge, we only got the Class-A's left. What's the plan?" Omega two formed in his right as Omega four pulled up to his left.

"Focus fire on the wounded Class-A first! In unison, target the chest, and trail down to the stomach!" Erwin's Raptor targeted the chest, along with his fireteam, "Fire!"

The R-6's revved up in unison, and unleashed a flurry of shells that hit their target. The Class-A stood no chance against their combined firepower, and like the Class-B's, was destroyed beyond regeneration. It slowly fell backwards, shaking the ground. That left two Class-A's. They were almost on top of them, only a few seconds for Erwin to formulate a plan… a risky one at that.

"Omega two and four, you all will take the Class-A I just marked. I'll take the other."

"Sir-"

Erwin cut him off. They didn't have the luxury of debate. "I will hold its attention, and try to kill it. I expect you all to finish your target quickly. Understood?"

"Yes-"

"Good! Move and be quick!" Erwin broke from the team, going for his titan. He activated his dash, and pulled his bayonet. In a risky maneuver, he went between the legs, and jabbed his weapon into the ankles of the titan. The titan let loose a howl of pain. It was a risky attack, but it worked.

Though, not everything can go according to plan.

The Class-A flung it's leg in pain, and Erwin hadn't taken his weapon out. The sudden jolt overpowered his machines booster and pulled him backwards while also ripping the arms off his Raptor. Erwin was fifteen feet off the ground for most of his flight, and crashed fifty meters from the titan.

"Warning, damaged sustained exceeds safe levels. Recommend pilot ejection."

Betty was correct. His Raptor was doomed. Erwin reached for his ejection handle and pulled. Though when he did, nothing happened. "Oh no…"

"Emergency hatch release has failed. Manually open the hatch to continue with ejection procedure."

Erwin didn't even bother to check to see of the Class-A had begun moving towards him yet. He didn't need to see what he already knew. Erwin pushed the canopy open button, but nothing happened. "Warning, multiple computer failures."

"Son of a BITCH!" Erwin screamed. There was no way to bail out. He'd have to climb out manually… and expose himself without any sort of weapon to the monster. It was a lose-lose situation, with one option having a smaller loss to it. However, he decided it would be better to at least try, rather than die. Erwin undid his harnesses as fast as he could, and reached for the manual locks on the canopy. The lock came undone on the left, and the right followed suit. He was free.

He was too late, though. The large Class-A was towering over him, and already reaching down. It's hand encased the cockpit, and Erwin closed his eyes, slumping back in his seat. He was done for. It was a regrettable end, and like he had told himself before, his death was another meaningless loss.

He waited, but ten seconds in, nothing happened. The hand hadn't squeezed, he then heard a loud crash on the outside. That was either one of his pilots, or the Class-A dying. He couldn't tell, and his communcations were dead. Silently, he waited. His hopes being that the Class-A was dead.

The hand was pried free from his cockpit, and above him stood two Raptors. Quickly Erwin pushed open his canopy and stood up, waving towards the pilots. Omega two opened his canopy, and extended a hand for him to climb into. "Good work, you two." He greeted. "I would've been dead for sure."

"No trouble, sir. Josh over there already called in the recovery transport. We are mission complete."

The sound of three rotor helicopters in the distance confirmed what the pilot said. "That it is. Excellent work, you two."