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Undertale: The Fallen Reploid

Summary:

(A cross-post of an Undertale Crossover on DeviantART of mine that I'm re-working into a fanfic)

While out on a mission in the Ebott Exclusion Zone to deal with a rogue Mechanloid, Axl finds himself curious about a legend surrounding the place and decides to stay behind to explore after convincing Alia that he'll be careful.

Things go wrong and soon Axl finds himself lost in a world of Monsters and with a strange newfound power. With no way to contact HQ or teleport out, Axl must journey through the Underground on foot. Along the way, meeting new friends and foes while also learning that listening to his trigger finger isn't the only option to solve a dispute.

Will he become the savior that Monsterkind and a group of outcasted Reploids speak of in an ancient prophecy or will he perish like the human children that came before him?

Chapter 1: Prologue/Solo Mission: Mt Ebott

Chapter Text

Long ago, two races ruled over Earth

 

HUMANS and MONSTERS

 

One day, war broke out between the two races.

 

After a long battle, HUMANS would come out victorious.

 

They sealed the monsters underground with a magic spell

 

Centuries would pass and technology would advance to the point that it would give rise to a new race called REPLOIDS.

 

While the two races on the surface would live in relative peace. Rogue Reploids known as MAVERICKS would soon rise up.

 

Countless conflicts and disasters to the surface would follow.

 

Monsterkind would remain relatively unaware and safe from these events.

 

In time, the memory of the Human Monster War would fade into nothing but legends and tall tales passed down from parents to children as a warning.

 

Yet that didn't deter a curious few children who would dare venture up Mount Ebott and never be heard from again.

 

Seven children would vanish in total before the area around the mountain would be made into an Exclusion Zone, including that of a long since abandoned city on the outskirts of the mountain and a dump that had been established within the nearby mountain range where the remains of many former Mavericks would be left to rot.

 

Few, save for high ranking Hunters and certain mechanloids working in the dump would be permitted within the area.

 

Well... that is unless stated otherwise....

 


Mount Ebott

 

21XX

 

"I'm picking up possible Maverick readings near the Mount Ebott region. Our surveillance systems have indicated that it appears to be some sort of Mechanaloid on route southbound towards checkpoint S4.

 

Any and all B Rank or above Hunters that are able please report to the Command Center for further instructions."

 

Alia terminated her announcement with a single button press as she turned around to look up at the Commander who had been silently sitting in his seat, watching the map on the large monitors with his usual stoic expression.

 

Signas let out a frustrated sigh as he took his look away from the predicted trajectory that the Maverick was likely to take. Thankfully the threat had been rather low as no major Human or Reploid civilizations stood nearby, having been long abandoned since the Eurasia Crisis meaning that at most the roving mechanical menace posed a threat to the slowly recovering local flora and fauna at the very least for the time being.

 

Yet that situation could easily change should the Maverick Hunters leave it unchecked.

 

The few high ranks who had been available had already made their way into the room just as their Commander rose to his feet, ready to give out the briefing.

 

"As you may have heard over the intercom, we have picked up reports of a fairly large Mechanloid within the Ebott Exclusion Zone. This area is strictly off limits following several reported cases of missing children dating as far back as the last century save for those with special permission, which is why you have all been called here." Signas made a gesture towards Aila who pulled up a still image taken from one of the several camera feeds planted around the perimeter.

 

The image was a of a large draconic Mechanloid frozen in mid-flight amidst a barren unleveled landscape. It was a standard disposal unit built to work in these sorts of environments.

 

"We need B rank and above Hunters for this mission who can handle both the unbalanced terrain as well as knowledge in handling aerial targets. If you fit those criteria then please raise your hand. We will continue with your briefing once this meeting is adjourned."

 

Instead the room was met with silence as the high ranks began to converse quietly amongst themselves as no one in the room fit those qualifications.

 

"I don't think that's any of us. A majority of us here are from the Sea or Enforcer's Unit."

 

"The guys they're looking for are those from the Disaster Unit. They are the ones with all those fancy tools."

 

"Yeah dude, but they all got deployed. Remember the typhoon?"

 

"Us from the Air Unit could handle it. Then again, that would be a lot of manpower for just a single Mechanloid."

 

”I’m helping Douglas test out a new Rider Chaser so I can’t go anyways.”

 

"Don't look at me, I work in the Medical Unit. Lifesaver would kill me for this, metaphorically speaking . He’s been watching my squadron closely after Siren tried to play hero.

 

Plus the only three I can think of are Wyvern, Zero, and..."

 

Eventually the sea of whispers was broken as a Reploid amongst the crowd raised their hand as the Commander called on them.

 

"Both Zero and Wildfire Wyvern are unavailable at this time Commander. He's out handling a riot at a nearby shipyard and Wyvern's still undergoing repairs after her last mission ended in a bust. None of us who are free are really built to handle that sort of stuff." The B Rank explained much to the dismay of the Command Staff as Signas merely facepalmed, grumbling to himself about it being one of those days before the Reploid continued, having come up with an idea.

 

"But what about that newbie who helped with the Red Alert Crisis? Sure he's still a Low Rank but couldn't he handle this mission with those unique abilities he has?"

 

Chatter from the other Hunters would soon follow as they agreed with their colleague's suggestion. If it was anyone who could handle this mission then it was that newbie whom had been making rounds about the place on what he had done for the overworked Hunters that eventually X would cave in and allow him to officially join, abet assigning him one of the lower ranks.

 

Amidist the talking, Signas had remained quiet as he pondered on the suggestion. Sure had Axl proven himself to be more than capable for this sort of mission. But it had only been recently that he had been allowed to join the Maverick Hunters and as his current Rank showed, he wouldn't be permitted anywhere near there unless given permission which the Commander was well within the power of doing.

 

Despite that, there was one other that Signas knew he was going to have to take this up with regardless of whoever they send out. And that was going to be in a headache in its own right.

 

Eventually the chatter died down as the Commander went to speak.

 

"You make a good point there but I will have to take it up with X as well before I make my choice. He was the one who ordered to have the Zone put up in the first place and with Axl being a low rank he will require special permission to undergo this mission. I will inform you all of our decision once it is made, but for now, you are all dismissed."

 

With those orders, the crowd soon filed out back towards their stations leaving both Alia and Signas alone. Signas simply stood there with his eyes closed as Alia looked up towards her boss with a knowing look that this was not going to be easy.

 


It had taken quite a bit of work, but eventually X gave in and gave Signas his word that Axl would be allowed to tackle the mission under one specific condition...

 

That Axl was to go nowhere near the Mountain itself and that he would not remain there not a second later after the mission was complete.

 

Alia would be keeping a close eye on the shapeshifting young Reploid as he finally arrived just outside the gate as he was given the go-ahead to proceed.

 

The route to where the Mechanloid's location was one packed with steep cliffs which weren't much of an issue for Axl thanks to his hover ability. A few rogue junk and not-quite destroyed Mechanloids had also been out and about but those were quickly dispatched with a well placed shot.

 

Eventually Axl made his way to a cliff face not far from where Alia had traced the target's signal to.

 

He didn't have much time to stand around and admire the scenery as not but seconds after his arrival, an alert for an approaching target would ring out from his communicator as the target made itself known.

 

The large yellow plated body of a large dragon-like beast reared its head up from below the cliff. Locking eyes with the one sent to dispose of it, the Mechanloid's excavator shaped maw opened with a loud roar as it reared up, ready to do battle.

 

Axl was quick to dodge as the machine swung its bladed tail towards him, in which the Hunter responded with a shot to the head. Yet the bullets would only bounce off its armor plating.

 

"Damn, how am I supposed to hit this guy? It's entire body is covered in this stuff." Axl grumbled to himself as he dodged another attack. This Mechanaloid was no doubt built to handle stuff like this judging from the rough terrain. But even with that it was bout to have some sort of weakness.

 

And Axl would find his answer soon just as the creature opened its jaws, getting ready to bite at him as he fired a well timed shot into it.

 

The Mechanaloid reared back as if it had taken damage as Axl grinned to himself. He had just found this thing's weakness.

 

He would gourd it into trying to bite him a few more times until it had sustained enough damage. Eventually the Mechanaloid would lose its grip on the cliff face. It would try to take off but its CPU was far too badly damaged to process that as it eventually tumbled downwards, disappearing down into the valley below along with several boulders that it had knocked loose. The beast would be crushed beneath the rubble, buried in a rocky grave.

 

And with that another possible crisis had been averted as the rogue Mechanaloid was no more as Axl took a moment to pause and admire his accomplishment.

 

"That takes care of that. Another mission down!"