Chapter 1, First Day on the Job (setup, no sex)

Important Characters:
Gudao and Gudako: https://fategrandorder.fandom.com/wiki/Master
Mash: https://fategrandorder.fandom.com/wiki/Mashu_Kyrielight
Olga Marie: https://fategrandorder.fandom.com/wiki/Olga_Marie_Animusphere
Carmilla: https://fategrandorder.fandom.com/wiki/Carmilla

…

The red haired girl, Gudako, slowly roused from her deep slumber. She groaned as she sat up, her entire body a mess of aches and bruises. Looking over she saw the form of her dark haired twin brother, Gudao, his bare chest rising and falling gently as he slept. She reached out, lightly tracing a line across his decently muscled chest, just as bruised and battered as she was. She examined the Command Spells etched into the back of her hand, noticing that the pattern was whole again, and recalled the incredible series of events that had landed the pair where they were today.

It had started only yesterday, the first day of their new job as mages at Chaldea. They started off on the wrong foot, completely exhausted after having spent too much time indulging in each other the night before, and collapsed in the hall after a extensive physical assessment. They were awoken by the licks of a small animal and the gentle words of a girl. She introduced herself as Mash Kyrielight. She made cheerful small talk as she walked the pair to their introductory briefing, for some reason calling both of the twins 'Senpai' even though this was their first day.

The directors words droned on and on and the twins both fell asleep again in the middle of the briefing. They were woken up this time by painful slaps from the irate director and were subsequently kicked out of the presentation. Now without anything in particular to do, the pair decided to go check out their new accommodations, perhaps break in the new bed.

The pair had been lightly dozing, sweaty bodies entangled on the bed, when they were awoken by a deafening sound that shook the room. Red emergency lighting flickered on, dimly illuminating their surroundings. A blaring klaxon sounded over the intercom, occasionally interrupted by an evacuation order and a warning of an explosion and ongoing fires in the command room. The pair had always been the morbidly curious sort and were quick to rush into danger, so after hurriedly dressing they sprinted off to the command room.

The command room was a horror show. There were corpses and parts of corpses strewn around the wreckage of the room. Blazing fires and the dull red emergency lights were the only source of illumination, dimly lighting up the blood soaked room in shades of red. Between deafening blares of the siren it was almost eerily silent, the low crackling of flames the only sound apart from the ringing in their ears.

They heard a wretched cough. Running toward it they found the wounded form of Mash, a large pipe pieced through her abdomen. The pair rushed to her side, Gudao holding her head in his lap, holding one of her hands in his, Gudako putting both her hands around the pipe, attempting to stem the flow of blood. They were both drawn to the dying girl, wanting to feel her lifeblood, her pulse, as they ebbed. They did their best to comfort her, not putting their own desire ahead of her needs, but she was beyond their help.

"Sen…pai, please run." Mash croaked out, eyes flitting between both siblings.

It was then that something in the control room seemed to change, the bulkhead doors slamming shut, strange machinery spinning up. The previous announcement stopped, a new one starting.

Coffin Vitals: Masters baseline not reached.
Rayshift requirement not met.
Searching for qualifying Masters… Found.
Candidates No. 47, No. 48 reset as Masters.
Unsummon Program, start. Spiritron Conversion, start.
Rayshift starting in 3, 2, 1.
All procedures clear.
First Order, commencing operation.

…

For the third time since arriving at Chaldea, the pair was being awoken, for the second time it was by the licks of the odd animal. 'Fou', they remembered Mash calling it. They heard clashing sounds nearby. Looking up they saw Mash, no longer wounded and wearing strange form fitting armor. She was holding a giant slab in the shape of a cross, a hunk of metal no human should have been able to lift, let alone swing. But swing she did, the mass crashing through a red skeleton that had been attacking her. She immediately picked it back up, spun around and sent it crashing through a second skeleton. The dust settled and all was still. It seemed that, for the moment, they were safe.

"Senpai!, you're awake, I'm so glad." Mash said, relieved expression on her face, as she picked up the cross and ran up to the pair.

The pair just laid in the dirt mouth agape, staring at the burning world around them. It was an entirely different burning world than the one they had been in moments before. This one was outside, and a strange dark ring that seemed to bend the light around it took up a large part of the sky. Before they could even begin to gather their bearings they were startled by the appearance of a blue hologram in front of them.

"I finally got through! Hello? This is Chaldea Command Room. Do you read me?" it said.

The hologram was a Dr. Roman, chief of Chaldea's medical team. He barely had enough time to give Mash coordinates to what he called a 'leyline' before the image cut out. Mash prodded the stunned siblings, encouraging them to move.

As they walked Mash began to explain what she could. She started with the information the twins were supposed to have gotten at the briefing. Chaldea was a secret organization founded with the goal of 'preserving the reign of the Human Order, above all else.' To that end they had developed many projects. The most significant of which was the Global Enviornment Model 'CHALDEAS', a perfect replica of the planetary body of Earth, stretching both into the past and future. However, detailed observation of time and space were impossible with CHALDEAS alone. A second project, the Near-Future Observation Lens 'SHEABA' allowed for detailed observation of CHALDEAS. Up until recently CHALDEAS had confirmed the continuation of human civilization for at least a hundred years into the future, but recently it had started to predict the extinction of humanity less than a year off. In using CHALDEAS to try to find a probable cause they had found a dead zone that could not be observed in the Japanese City of Fuyuki in the year 2004. They named this dead zone 'Singulary F' and as their best lead Chaldea prepared to investigate. Chaldea recruited 48 mages as 'Master Candidates' to investigate the singularity. They were to be sent into the singularly by means of a technology called 'Rayshifting', where their spirit is projected back through time into the era in question. This is where something had gone awry, resulting in the carnage in the control room the twins had seen. The automated system had recognized the twins as the only remaining Master Candidates and had tried again with them as Masters. This time it seemed to have worked correctly, the burning landscape the three walked through now was Fuyuki, year 2004. Singularity F.

The twins asked Mash if she was also a Master Candidate, to which she shook her head no. She began to explain what exactly a Master Candidate is and why Chaldea needed them in particular. What sets apart a Master Candidate from an ordinary mage is the aptitude to summon 'Servants', spirits of ancient heroes, and bind them to their control as familiars. Mash explained that she herself had been part of a Chaldea experiment that attempted to fuse a Heroic Spirit and a human in what they called a Demi-Servant. A Servant had bonded with her, but had laid dormant, leaving her a mostly ordinary human girl. The project had been deemed unsuccessful and was discontinued. When the trio had rayshifed and the system recognized them as Masters the Heroic Spirit inside Mash awakened, granting her the power of a Servant and forming a contract between her and the twins. She explained that Servants were divided into classes, and that her class was called 'Shielder', that unbelievable slab of metal she held apparently her shield. As a Demi-Servant she had strength, speed, and durability well beyond that of an ordinary human, or even any mage. Mash did not know the name of the Servant she had fused with, and she didn't know the extent of the abilities she had at her disposal, of particular note her 'Noble Phantasm'. Noble Phantasms, she explained, were Servants single greatest tool, usually the most notable part of their legends. They could be weapons with the power to destroy armies single-handedly, to summon powerful monsters, or any manner of other powerful effects well beyond a mage's wildest ambition. Without hers Mash would be in a severely compromised position should they have to fight against another Servant.

Lastly she explained Commands Spells, the red symbols that had etched themselves into the back's of the twins hands. Command Spells are formed when a contract is made between a Master and a Servant. The three Command Spells are extremely powerful magic, they can be used to bolster a Servant's power, to give there attack more strength or give them a second wind. Perhaps even more importantly though was their ability to compel a Servant, to enforce an order that they were for some reason unwilling to carry out. Normally a Master would only have the three Command Spells they got when a contract was formed, and if they ran out they could be put in a difficult situation had they given their Servant cause for ire, but Mash was reasonably certain she remembered Chaldea having the facilities to regenerate lost Command Spells. She urged caution, saying they shouldn't waste them needlessly, but also saying they shouldn't hesitate to use them should their use be required.

The trio continued their hike in the direction of the leyline, Mash easily smashing through a few more skeletons on the way. On the way they encountered Chaldea's director, Olga Marie, Mash saving her by smashing through a skeleton that had cornered her. She hadn't seemed particularly grateful to have been rescued, and complained loudly while they walked.

When they reached the leyline Olga Marie and Mash busied themselves, linking Mash's shield, hoping to use the focus of the leyline and Mash's deep well of Servant mana to cut through the noise and contact Chaldea. It worked, the blue hologram of Dr. Roman popping back into view. The next several minuets were filled with heated conversation. The pair of Masters just stood back as Olga Marie shouted and Dr. Roman did his best to pacify her while still explaining the situation.

The explosion had taken most of Chaldea's functionality offline and gravely wounded, perhaps fatally the remaining 46 Master candidates. Olga Marie had Dr. Roman put them in suspended animation, until a time when Chaldea had the time and resources to deal with them properly. Dr. Roman was prioritizing the repair of the rayshift equipment to bring them back, but until then they had no choice but to investigate the singularity.

The decision was made to attempt to summon another Servant. Mash was a primarily defensive Servant, and while her Servant body was strong enough to easily fight everything they had encountered so far, they could be in trouble were they to encounter another Servant. Chaldea had only successfully performed a summoning three times out of many attempts over many years, and only the Servant now possessing Mash and one other were still around, but Dr. Roman was optimistic in their chances now that they had two full fledged Masters. Mash's shield tethered to the leyline served as their catalyst. The two Masters stood at the two arms of the cross and chanted a incantation provided to them by Dr. Roman.

Magic circles appeared from the shield as they chanted, golden rings spinning and sparks flying as they gradually gained speed. A tall form began to take shape in the blinding light, and with a small bang the light shot outward, leaving behind a human form. The Servant was a beautiful woman, with skin paler than any the twins had ever seen. Her outfit did little to conceal her beauty, criss-crossing leather connecting what amounted to little more than a fetishistic set of black leather bra and panties. She wore a long red skirt that didn't meet in front, her long pale legs clad in dark thigh high stockings and tall heels. She had a pair of tall horns pointing straight up on her head and she wore a short mask concealing much of her face. She carried a scepter and behind her stood the looming form of an iron maiden bound in chains.

The woman casually surveyed her slack jawed Masters before opening her mouth to speak. "Ah. I guess this must be fate. Please call me Carmilla. I am an Assassin-class Servant."

The group began to explore the town, Carmilla and her Masters talking as they walked, familiarizing themselves with each other. Her true identity was that of Elizibeth Bathory, a 16th century noblewomen from Hungary. In life she had tortured, mutilated, and murdered hundreds of girls in the prime of their young lives, bathing in their blood in the pursuit of youth. As her legend was repeated throughout the centuries it had become embellished with tales of vamprism, and this had manifested in the alias of Carmilla, as well as several of her abilities as a Servant. As they talked she only gave brief curt responses to her male Master, while giving her female Master her full attention as she readily recounted the lurid details of her crimes, the look in her eyes sending a shiver up the girl's spine.

The group fought several battles as they explored, handily defeating each encounter, Mash handling the defense, Carmilla relishing in the offense. They encountered a shadow Servant, a Servant who had lost their sense of self and who attacked ceaselessly as long as they could still move. With this loss of self their attacks lost much of their strength, their experience and techniques forgotten, and they proved little challenge for the combined might of Mash and Carmilla.

They briefly encountered a dying still lucid Servant. He spent his last moments telling them his story before passing, his Servant body dissolving into gold dust that blew away on the wind. He had been one of seven Servants summoned for a battle for possession of a Holy Grail, said to grant any wish. A Saber class Servant had won the battle, and the city had been reduced to its current state. He had barely survived the final battle, crawling away to die on his own terms. Apart from him and the Saber, the few Servants that had survived to the end had been reduced to shadow Servants.

The Servant had told them where the final battle had taken place, and the group decided to head that way. They hoped that they might find and defeat the Saber Servant, assume control of the Grail and set right this world, or at least find some clue of how to do so. The encountered many enemies as they drew closer, there were some tougher skeletons that didn't look entirely human in nature that Dr. Roman called 'Dragon Tooth Warriors', and there were a few more shadow Servants. The battles became progressively more difficult, but Carmilla and Mash handled each encounter with expert proficiency.

Eventually the group reached the mountain where the final battle for the Grail had taken place. They found a cave in the side of the mountain and followed it to where it let out into an enormous cavern. In the center stood the Saber class Servant, standing tall and proud, hands resting on the pommel of her sword stuck in the ground in front of her, posed as if she had been waiting for them. She seemed particularly interested in Mash, her pale yellow eyes sparing only a brief glance for Carmilla and completely ignoring the rest of the party. She briefly spoke, expressing the desire to 'test the truth of your shield', before she launched herself forward, armor materializing out of thin air to cover the black dress she wore.

Sparks flew as sword clashed off shield. A cacophony of sound erupted as a flurry of swings were blocked faster than human eyes could follow. The twin Masters and Olga Marie could do nothing but gawk as the two Servants fought. Carmilla was content to stand back as well for the time being, evaluating the skill of both friend and foe while also admiring the sight of their lithe youthful bodies.

Suddenly the Saber disengaged, distancing herself and assuming a stance with her blade held high above her head. Vast quantities of mana coalesced into ribbons of darkness that swirled around her sword.

"Everyone get behind me!" Mash yelled. "She's going to unleash her Noble Phantasm!"

As Mash had became more familiar with her shield through the last several hours of battle she had gained the ability to grant her Noble Phantasm a Psuedo True Name and the ability to use it, albeit at a reduced power. As the Saber Servant gathered mana and her companions gathered behind her Mash assumed her own stance and held up her shield, preparing to unleash her Noble Phantasm in turn.

Both Servants began to chant at nearly the same instant.

"Vortigern, Hammer of the Vile King, reverse the rising sun. Swallow the light, Excalibur Morgan!"

"True Name, pseudonym registered. Deploying Noble Phantasm. Lord Chaldeas!"

As she finished her chant the Saber Servant swung her sword down, the accumulated power bearing down toward group in an enormous beam. Mash finished her chant just in time, smashing the base of her shield into the ground in front of the group. Geometric shapes ballooned from the center of the shield, increasing in size until they formed a magic circle at least five meters in diameter. Powerful rings of energy began to radiate out from the center, covering the circle in a thick shield of condensed mana. The beam of energy crashed into the shield, flattening into a giant disc and tearing a giant furrow into the ground. The onslaught did not let up, time seeming to stretch forever as Mash fought with all her strength to hold back the Saber's Noble Phantasm. The edges of the giant shield began to crumble, the giant disc of destruction narrowing into a cone around it as it continued to tear into the ground in all directions. Scorching heat and sharp fragments of stone washed over the group as the shield weakened.

"Masters!, I can't hold for much longer." Mash yelled. "If you use a Command Spell I should be able to hold on a few more seconds!"

Gudako felt a hand on her shoulder, turning to look she saw Carmilla looking at her.

"Master, use one to strength me as well, I'll use my Noble Phantasm to take the enemy out while she's distracted." she said.

The two Masters looked at each other and nodded. They turned their backs to each other, Gudao facing Mash and Gudako facing Carmilla. They held out their right hands emblazoned with the Command Spells, and tightly clasped their left hands together behind their backs. In unison the pair began to chant.

"By the power of my Command Spell, I order you, unleash your Noble Phantasm!"

A spell from each of their hands glowed bright red before fading, leaving behind only a faint smudge. Mash roared as renewed power flowed through her, the shapes of the magic circle glowing brighter than ever as they reformed. The cone of destruction was once more pushed back as the shield regained its strength.

"Blood, blood, blood…! Eternal beauty, an eternal banquet, it is time for the end of the ugliness of old age───. Phantom Maiden! Fuhahahahaha, ahahahahahahaa! Ahahahaha…!" Carmilla cackled, an almost sensual tone to her voice, ringing clear even through the din of destruction surrounding them.

As she finished her chant the iron maiden she carried disappeared from behind her, leaving only chains lying in the dirt. Almost immediately the onslaught stopped and Mash dropped her shield to the ground, falling to one knee and breathing heavily. The shield fell just in time to see the doors of the iron maiden close around the enemy Servant, sickening sounds of rubbing metal echoing through the now suddenly much quieter crater. Blood began to pool from the base of the maiden, and both Masters felt an exhilarating rush, mostly from the exhilaration of having survived an event of literal earth shattering magnitude, but also from imaging their beautiful opponent having just been skewered dozens of times over.

The iron maiden stood tall in the silence for just a moment before shimmering and disappearing, materializing once more behind Carmilla, the chains rising from the ground to once more snake their ways around the instrument.

The enemy Servant was left standing there, seemingly unhurt for a moment before collapsing to one knee, only prevented from collapsing completely by leaning on her sword. Her armor had been shattered and fell from her body in great chunks, dissolving into thin air as it hit the ground. Her dress beneath was tattered to ribbons loosely hanging off her frame, threatening to fall off completely at the slightest provocation. Some did, a creamy pale thigh and the soft swell of one of her breasts coming into view as she drew ragged breaths. She was covered in deep wounds, blood pouring out over her skin and dress, the red contrasting deeply with the white and black. She struggled to raise her head to face her opponents, one piercing yellow eye looking at her conquerors, the other either too caked with blood to open or destroyed entirely by a spike. She fought to draw breath, to give a few parting words to her enemy with her failing body.

"I was going to defend the Holy Grail to the end, but it seems I will always meet the same end if I'm alone. You wield that shield well, perhaps you will even prove worthy of it in the trials to come. Grand Order, the battle to obtain the Holy Grail has only just begun."

With those cryptic words she collapsed face first into the mud with a wet thud, body dissolving into gold dust and blowing away. Where she had been a glowing golden chalice now floated a foot from the ground.

Everyone but Carmilla collapsed to the ground, breathing heavily and just trying to wrap their mind around their victory. Carmilla did her best to remain regally composed, but an astute eye could notice the increase in her breathing and the sweat on her brow.

A slow clapping began to echo throughout the cavern. Looking about for the source the group saw a familiar looking man in green perched on a ledge overlooking the cavern. Olga Marie yelled in excitement, running toward the man while shouting words of relief. She began to falter a little as she recognized something off about the demeanor of the man she knew. The man, Lev Lainur Flauros, was a senior technician at Chaldea. He revealed himself as the orchestrator of the explosion, and expressed surprise that Olga Marie was alive, since she had been the foremost target of the attack. He said that should Olga Marie attempt to return to Chaldea she would die immediately, her physical body there having already been destroyed, her rayshifed spirit in the singularity the result of some odd fluke.

Lev thrust one hand towards the Grail, it flew to his hand from where it had been floating, his hand closing around its stem. The other hand he thrust towards Olga Marie, who similarly went flying to Lev, his hand closing violently around her neck, a pitiful strangled cry escaping. He gestured the Grail and in front of him a circle began to expand. Through the circle was Chaldea's command room, and the burning red sphere of CHALDEAS. Lev thrust his hand holding Olga Marie through the portal, shoving her against the burning ball of fire.

Olga Marie screamed. She screamed in anguish at the crushing betrayal of a trusted aide. She screamed in horror at her family's life's work CHALDEAS, which now displayed a world of burning flames, all traces of life scoured from its surface. But most of all, she screamed in agony, her body splitting apart at a fundamental level as she reentered Chaldea where her body no longer existed, and what had yet to fall apart was burnt in the hellfire of Earth's fate. Her screams faltered and faded as she sunk below the surface of the sphere, one outstretched hand dissolving into nothing before it could follow her under.

Lev lazily tossed the Grail aside where it landed a few meters away from his huddled enemies. The cavern loudly creaked and large chunks of stone rained down from the ceiling as the cavern began to collapse. Lev gloated that he had succeeded in his task, that the age of humanity was over, all of humanity gone. Chaldea had managed to avoid destitution for the moment, but Lev said there was no need to kill them, he had already won and they too would fade with time. He then bade farewell to the last remnants of humanity before turning and disappearing in a flash of light.

Mash rushed to her Masters' side, shielding them from the falling debris as she yelled at Dr. Roman to rayshift them out of the cavern collapsing around them.

…

When the pair came to for the fourth time they were lying on the floor of Chaldea's command room. They were greeted by Mash and Fou, who were both happy to seem them awake and unharmed. Between them lay the Grail, though neither of them remembered grabbing it. They were approached by a beautiful, oddly familiar looking woman who introduced herself as Leonardo Da Vinci, a Caster class Servant and Chaldea's third successfully summoned Servant. Da Vinci together with Dr. Roman began to explain the situation.

In the wake of what had transpired in the Fuyuki singularity, Chaldea's equipment had found seven more singularities, all significantly larger than the one they had just visited. Each of them was a pivotal point in Mankind's history, and they had all been destabilized, throwing a wrench into history and creating the destroyed world that CHALDEAS displayed. There had been attempts to contact the outside world, but there had been no reply, the outside world was already gone. CHALDEAS' magnetosphere and continued analysis of history were the only reason Chaldea still stood. Chaldea's mission had changed from one of scientific curiosity to being the last hope to save all of human history. Armed with two Masters, if they could summon Servants, visit the singularities, and avert the disasters that sent history off course, there was yet hope for the salvation of mankind.

Dr. Roman asked if the pair were ready, if they were prepared to shoulder the hope of all humanity's future.

The twins looked at each other, grabbed each other's hand, and turned to Dr. Roman. They squeezed their hands, taking comfort in each other's presence and responded. "Of course."

Dr. Roman, as Chaldea's new acting director, declared their new mission, Grand Order, formally undertaken.

The two Masters were exhausted after their very long day, but before releasing them to rest Da Vinci brought them to the summoning room and had them summon a half-dozen more Servants. Da Vinci wasn't entirely satisfied, but she could see that the two Masters were at the limit of there mana supply and ability to stay on their feet, so she let them go.

The exhausted pair trudged to their room where they stripped down and rinsed off the worst of the blood and grime that coated them before collapsing into the bed.

…

Gudako had been half in shock the day before, but as she watched her sleeping brother and reflected the magnitude of their situation hit her. They were humanity's last hope, all of human history rested on their shoulders. It was a truly daunting task. The twins would absolutely give it everything they've got, but still, it was quite intimidating. She recalled Olga Marie's screams, the sight of their enemy perforated with holes, feeling Mashes blood pour around her fingers, and a shiver ran up her spine. One hand found its way under the sheet, slowly crawling along her thigh.

It was then that she noticed Carmilla standing in the door frame, watching her. Carmilla smiled at her as she hurriedly pulled up the sheet to cover herself.

"Excuse me Master for disturbing you so early. I was wondering if you would be willing to help me with something." Carmilla said.

"Oh, a, sure." Gudako replied.

The pair just stared at each other for several long seconds, neither moving.

"I'll be out in a minute if you could just wait outside." Gudako said.

"Of course, Master." Carmilla replied, smiling wryly as she turned and left, door closing behind her.

The girl dressed quickly, doing her best to ignore the aches of her body. As she prepared to exit the room she wondered what Carmilla needed her for.