Disclaimer: I do not own the Fate franchise it belongs to Kinoko Nasu and Type-Moon.

Transposition

Chapter 18

What little light there was in the tunnel glinted off metal and fluids of various kinds, a red spear flickering in a complex pattern as it cut through a set of wildly-flailing tentacles. And then, pressing the initiative, Lancer severed the entire set of tentacles from the rest of the monster's body, and in an upward stroke split it into two.

The monster fell, letting out a pitiful cry as it died. Undaunted, Lancer advanced, his spear flourished overhead as he let out an Irish war cry and trampled the monster's remains under his feet. Others more like it littered the tunnel behind, and more of them waited up ahead.

A monster spat a glowing green sphere at Lancer, only to explode harmlessly against the Servant as runes daubed by Lancer on his torso briefly glowed before dulling. It didn't even faze Lancer a bit, leaping forward and using his spear to anchor himself to the ground. A kick threw the monster back, and then Lancer pulled his spear in and up, shearing the monster's head off.

More monsters charged in, from the front and back, vaguely reptilian in appearance if scuttling on six, insect-like legs. Arms ended in wicked, scythe-like things, bone or chitin or whatever they were made from cutting at the air as they rushed Lancer.

The tunnel was wide thankfully, no doubt to allow modern maintenance vehicles – albeit small ones – passage when needed. In this case, it allowed Lancer to utilize his spear to a greater extent than would expected in such a confined space.

Snarling in frustration and battle fury, Lancer took the initiative, skewering three monsters before ripping his spear free. Drawing it back, he slammed the butt against the ground and using it to anchor himself flipped through the air to land atop a monster behind him, and crushing it into the ground.

The spear arced around Lancer as he carved up the closest monsters, and then advanced after having secured his back. Roaring his war cry, Lancer charged, skewering two monsters in front and pierced their ranks. Ripping his spear free, Lancer cut down another monster behind him before dodging one then two blows from the second.

Metal flashed and the monster flinched back as Lancer cut a gash across its face, and then it stilled and gurgled before dying as Lancer flourished his spear and stabbed the monster from below its head. Pulling his lance free of the corpse, Lancer looked around in the darkness, and then after a moment held out a finger.

Unearthly light glowed as he wrote a series of runes in the air, the symbols flashing once as he finished and then curving back, began to orbit a small sphere of light. Angry snarls could be heard from further down the tunnel, and with a gesture Lancer threw his light in its direction.

Shadows flared, lengthened, and vanished as the light sped down the corridor, and then angry snarls turned to ferocious howls as the light entered a gallery of some sort and sped up, casting the gallery below in wan light. Crouching down slightly, Lancer sped forward in a blur, and then leaping through the gallery entrance took long strides into the chamber before jumping up, toward the gently-sloping ceiling, and grabbing hold of a pipe looked down and around the chamber.

It was a junction of some sort, a cluster of pipes running down one side of the wall from the center of the dome-like ceiling, and passing through a large, rectangular block vanished into the ground. More pipes ran horizontally at knee-height on the other side of the room, and through several smaller metal boxes before vanishing into the wall.

What really caught Lancer's attention were all the sacs of twisted flesh across the room, recessed into the stone construction. Vague shapes could be seen inside, and Lancer could see the remains of other sacs, stinking and festering in the enclosed space as the fleshy matter they were made from rotted away.

The sacs were largely on the floor, while others were recessed into the walls. Others hung down from the ceiling on twisted, rope-like strands of flesh, squirming unpleasantly. "This is a nest." Lancer thought in disgust. "A nest of abominations, that is."

One sac was quite close to Lancer, and it squirmed and jiggled unpleasantly. Feeling his stomach turn, Lancer cut it open with a swing.

Pale fluid spilled out, along with looked like a Human fetus…if Humans had no noses and simply had slits for nostrils, along with limbs ending in tentacles. Its eyes were pure black, with no eyelids or visible irises.

It mewled piteously as it fell, striking the ground in a wet slap. The sights and sounds made Lancer regret what he'd done, if only because it made his stomach take another turn for the worse. "I don't know whether or not to hate Kirei for making me do this." Lancer thought in disgust. "On one hand, this place – and others like it – needs to be stamped out and burned, which I'm more than happy to do. On the other hand, this place is disgusting."

Lancer blinked as angry, territorial snarls echoed from below, and he looked down. There were four of them, ape-like things covered all over with overlapping scales, with no visible eyes but with fanged mouths. They clustered around the remains of the…thing, that he'd cut out of a nearby sac.

Almost as if…

…ah, I see. Not happy I killed one of them eh? Don't care; I'll kill each and every one of these things that I come across.

Smirking to himself, Lancer glanced at the sacs hanging down from the ceiling, and sprang from his side of the wall to the other. As he leaped through the air, his spear flashed, cutting through the…ropes, that held the sacs to the ceiling.

They plummeted, smashing against the ground and spilling sticky fluid while the creatures inside thrashed and convulsed before dying. The creatures – some sort of nest guardian probably – snarled and roared in anger, running up against the walls and struggling to get to Lancer.

Lancer just smirked, and gestured at the guardians. They pawed and struggled to climb against the wall, and then to Lancer's surprise one of them ran to the other side of the room, and used the pipes running up to the ceiling to clamber up to Lancer's level.

Smart, aren't you?

The guardian roared a challenge at Lancer as they both tensed, and then leapt through the air at each other. Ichor fountained as Lancer stabbed the guardian through the mouth, his spear running through its body nearly lengthwise before emerging dripping from its back.

The two of them slammed against the ground, the guardian dead and its pack mates closing in. Snarling in his turn, Lancer abandoned his spear and dove back as one of the guardians brought down its fists with a roar and crushed its pack mate's corpse.

Flipping back a couple of times, Lancer hissed in displeasure at temporarily losing his weapon, but then a shadow loomed down from behind. With a roar, another guardian attempted to attack from the rear, only for Lancer to dance to one side and then in close.

A fist buried itself into the guardian's belly, scales breaking as Lancer's fist sank into the soft flesh beneath. A split second later and Lancer's free hand shot up, more scales breaking as Lancer crushed a grip beneath the guardian's chin.

Roaring, Lancer hurled the guardian at one of its pack mates, and knocking both of them away. And then, leaping forward he jumped off their bodies and over and past the last guardian to land next to the fallen guardian's mangled corpse.

"Oh no…this is fucking disgusting…I'm washing this when I get back, and to hell with the priest's comments." Lancer thought in disgust as he felt the slime and ichor coating his weapon.

He didn't have much more time to think on that though, as the closest guardian was charging in. Flicking as much slime as he could off his spear, Lancer backed off initially, spinning and flourishing his spear before dancing in. Two strokes carved through the guardian's legs, and Lancer danced back as it toppled forward.

Another flourish, and then Lancer stabbed the guardian in the head.

Pulling the spear back, Lancer glanced sideways twice and then dove forward, rolling to turn in a crouch. The remaining guardians had tried to flank him, but Lancer's dodge had caused them to pounce at each other instead, the two guardians slamming into each other loud and hard, and causing them to fall, dazed and shaken against the ground.

…and offered Lancer an opportunity.

Red metal flashed and a guardian screamed as a foot was rendered useless. Quick footwork avoided a counterattack by the other guardian, with Lancer's counter cutting a gash across its chest. As it staggered forward, Lancer dodged to the side, and dancing past cut its right leg open before arriving behind the guardian.

Red metal flashed again as Lancer stabbed the guardian from the back, the spear punching through to emerge dripping from the guardian's chest. Lancer pulled it back, and swung, shearing the back of its neck open.

Howling in agony, the guardian collapsed, Lancer stepping past even as he quickly stabbed the guardian in the head, and putting it out of its misery.

The last guardian struggled to back away from Lancer, whining piteously, and Lancer came to a halt. He cracked his neck, and sighed.

"Sorry," he said, surprisingly sympathetic. "But I have to do this."

No, it's not sympathy. It's pity.

Poor bastards, but we can't leave these…things, on their own. Even I know that much.

With a shouted war cry, Lancer jumped up, flipped through the air and landed onto the guardian's back, sinking into a crouch as he buried his spear through its head to emerge dripping from below the chin. The guardian stiffened and then stilled, slumping to the ground in death.

For a couple of moments, Lancer stayed silent and still, and then with a sigh, rose and pulled his spear free. He glanced around him a few times, and narrowed his nose in distaste.

The heat of battle had driven it from his mind, but now that the battle was done, the disgust of where he was returned. Worse, many of the sacs were squirming in agitation, the monsters inside seemingly provoked by the death of the guardians.

Right, let's get this done and get out of here. I still have to tell that damn priest about this, and I hope he's got a plan on how to deal with this.

There's probably more nests like this somewhere out there, and we have to get them all.

But, with that said, finding and stamping them out one by one is going to be a pain.

Lancer scowled at the thought, and at the knowledge this would only result in more jokes about his name. "Damn that priest and his 'friend'." Lancer thought in disgust as he wrote more runes in the air.

Flames ignited with a whoosh and spread quickly, alarms elsewhere beginning to scream as fire consumed the guardians' bodies, the sacs, and the remains of the monsters. Lancer walked away unconcerned, knowing the flames he'd set would die once they'd done what they were supposed to do, that is consume the monsters' bodies and ensure no real trace of them would be left.

And he'd left quite a bit of bodies lying around on the way here.

I might have to start more fires that just this.

Steel rang and a woman's shout pierced the night, followed by the sound of steel clattering irregularly against stone.

Rider fell, tumbling down the stairs to a lower landing. She recovered in but a moment, rolling back and up to her feet, crouched and with her sword held protectively before her.

And across her torso, the steel plate of her armor was marred by a single gash that carved through the metal. Any deeper and it would have cut through the rough cloth underneath and then the flesh below.

"I'm impressed." Assassin remarked from above with a respectful expression on his face. "You blocked two out of three strikes. But…"

Assassin trailed off, his eyes narrowing as they focused on the gash through Rider's torso armor. "The third should have connected." He said. "No, it did connect. It's just that you were standing close to the edge of this landing, and when the force of the other strikes was transferred to your body, it threw you back, and kept the third strike from striking true."

"Nothing wrong with being lucky." Rider remarked before narrowing her eyes behind her mask. "Tsubame Gaeshi…"

Rider trailed off and laughed. "Don't worry, I'm not mocking you." She said afterwards. "I'm mocking myself, you see."

"Oh?"

"If anyone had told me about Tsubame Gaeshi before I experienced it for myself, I'd have laughed at the notion that nothing but pure skill could be a Noble Phantasm in itself." Rider said with a shrug. "After all, Noble Phantasms are the embodiment of our legends, usually taking the form of our swords, armor, or sometimes even magic spells."

Rider paused and grinned. "Even though I knew what I know now after you revealed your identity," she said. "That it reaches into the realms of True Magic, that 'Multi-Dimension Refraction Phenomenon' or something that allows you to strike three times from three directions all at the same time…"

Rider paused and laughed. "Yes," she said with a nod. "In hindsight I can see how just skill with the sword can become a Noble Phantasm in itself."

Assassin smiled and briefly closing his eyes, lowered his face. "Rest assured, I take no offense." He said. "And I am honored that you acknowledge my skill. But if I am honest, I simply wanted to catch the sparrow."

Rider stayed silent as Assassin paused, looking up into the night sky. "It's just that the sparrow can sense the changes in the wind, and change its path instantly." He said. "To catch up, all its routes have to be cut off…at the same time…"

Assassin trailed off, the two Servants staying silent for several moments before Assassin sighed. "I had cursed myself you know," he said. "Being summoned into this filthy world, but…"

Assassin paused to turn back to Rider. "To be able to use my secret technique against a worthy opponent," he said. "It makes it all this worthwhile, even if none other were as worthy as you."

"Do you really think there aren't?" Rider challenged.

"I do not know." Assassin replied. "With that said, you are Rider, are you not? The three Servant Knights are supposed to be superior to you."

"And yet you're an Assassin," Rider shot back, ignoring the implied jibe at her class. "And thus supposed to be inferior to me."

Assassin just smiled and gave a small nod of acknowledgement. "The point is well made." He conceded.

Rider grinned wider and tensed. "Shall we continue then?" she asked.

Assassin briefly closed his eyes before looking away. "Tempting," he said. "But it would be pointless at this point, wouldn't you say?"

"What?"

"Your Master's attack on the temple has failed." Assassin said. "The survivors have fled. There's no point in continuing this battle. But,"

Assassin paused, turning back to Rider and narrowing his eyes. "If you wish to continue," he said. "Then come. As I told you before, my responsibility is to keep enemies from passing through the gate behind us. Come then, and let us finish this battle."

Rider stood silent and still, and after a moment, Assassin continued. "But," he said. "It's too soon, don't you think, to fight to the death? The war is well underway, but things have yet to truly step up. There's no need to rush, is there?"

Rider stayed as she was a moment longer, and then with a sigh relaxed. "I suppose you have a point." She reluctantly admitted. "Why rush when you can take the time and savor fighting worthy opponents over the course of the war?"

Assassin smiled, only for Rider to point her sword at him. "Just remember," she said. "You owe me a battle. Until you can you pay your debt, don't you dare get yourself killed by someone else."

Assassin nodded. "I look forward to it then." He said, before half-turning away with a nod. Rider nodded back, and after a few moment staring at each other Rider vanished into astral form. Assassin smiled wider before turning back to the temple gates, and climbing up likewise vanished into astral form after a few steps.

"The operation failed."

Shinji glanced sideways, towards where Rin was sitting behind her desk. The chair was turned to face the window so he couldn't see her face, but from the sound of things, she didn't seem concerned in any way at all.

You could even say it sounds as though she expected this to happen.

Why?

And if so, why launch this operation regardless?

Shinji narrowed his eyes. "Going through the motions to satisfy the worm's demands to drive Caster from the mountain? Or…" Shinji thought before speaking up. "What do you plan to do after this?"

Rin didn't reply at once, instead getting up to walk closer to the windows, and looking out into the night. "I had hoped for a success." She said. "Maybe not Caster being defeated, but at least driven from the temple. But, I also knew the temple was her stronghold, and thus a battlefield that would favor her."

"So, you hoped for success, but expected failure, is that it?"

"As you say,"

Shinji briefly looked away in thought, before sighing and getting up. "And?" he prompted.

"The operation did fail," Rin said, turning to face Shinji. "But it's no big loss either. Rider safely retreated, and the Children that were killed – including the Alpha of all things – can be easily replaced. And…"

"And?"

"Lessons and vital information were obtained during the battle." Rin said, stepping around her desk to sit closer to Shinji. "For one thing, we now have field data to develop a resistance or even immunity to the bounded field around Mount Enzo. The way the battle with Caster progressed also provided useful information on optimal paths for future evolutions of the Children. And now we also know who the last Master is: Caster herself."

Shinji looked surprised. "Is that even possible?" he asked.

"Given she summoned Assassin," Rin said. "It clearly is."

"True," Shinji admitted. "And the Assassin? Anything about him?"

Rin burst out laughing at that, but calmed after several moments. "Sorry," she said. "I couldn't resist. He seems to be an archetypal samurai, all 'swords are all that is needed between worthy opponents' or something of that sort, and actually introduced himself by his true name."

"That's not necessarily a bad thing, you know." Shinji said reprovingly.

Rin gave him a slight glare but relented in a moment. "True," she said. "While it's very…fantastic, were people more…honorable or…virtuous, and genuinely so at that, the world would probably be a better place. But sadly, it's not."

Rin paused, her eyes narrowing at broken promises and sweet lies masking bitter and poisonous intent. "It's definitely not." She said.

Shinji didn't reply at first, instead looking away in melancholy contemplation of Rin's words before another thought occurred to him. "Wait, what about Rider?" he said. "Did she…?"

"No, her identity's uncompromised." Rin said. "Though it nearly was; as you suspect, after Assassin identified himself, Rider – in the spirit of chivalry – almost revealed who she really was. Thankfully for us though, Assassin realized he may have pressured Rider unintentionally, and absolved her of responsibility to return his introduction in kind."

"How noble of him."

Rin's lips twitched with amusement but she didn't say anything more. "Still," Shinji continued. "While it's expected – and surprising – considering who Rider is and what she once was, it could prove problematic in the future."

"No," Rin disagreed. "Her identity getting out is inevitable, one way or another, so I'll leave it to her discretion when and where to reveal it. I'll trust her with that much, and besides, I don't want to push either. She's not happy about the Children, and while neither of us are either, even so…"

Silence fell between the two siblings, thickening the air around them for several moments as they brooded on the path they'd laid out for themselves in the hope of victory. Largely by Rin yes, but Shinji had contributed his fair share, despite his greater misgivings about the whole project.

We're both responsible for what we did to our own, and what they've done for us afterwards.

Shinji took a deep breath, and turned back to Rin. "So," he began. "Going back to Assassin, who is he?"

"Sasaki Kojiro."

Shinji's eyes bulged. "Sasaki Kojiro?" he echoed incredulously. "As in the rival of the legendary Miyamoto Musashi? That Kojiro?"

"The one and only apparently," Rin said with a grin. "And yes, his Noble Phantasm is nothing less than the legendary Tsubame Gaeshi."

Rin paused to chuckle before leaning back with an expression of awe on her face. "Rider showed me." She said. "It was beautiful. A true miracle, there's no question about it. With nothing more than his own skill with the sword and a lifetime of practice, Assassin was able to surpass the limitations of the World and achieved the Multi-Dimension Refraction Phenomenon."

"That's an aspect of the Second Magic."

"Yes, it is." Rin confirmed. "And that's how he did it. That's how he caught the sparrow in mid-flight. He cut his target with three strikes from three different directions all at the same time."

Shinji smiled and nodded in agreement. "Hard to think someone who isn't even a magus in the remotest sense of the word could achieve something so profound as True Magic, or at least an aspect of it." He said.

"True," Rin said with a shrug. "Though, you could say Assassin's single-minded pursuit of his goal isn't too different from ours either."

"Also true." Shinji agreed, the siblings sharing a shrug between them. Afterwards though, Shinji looked slightly concerned. "I wonder though, how Caster was able to summon a Servant."

"I'm not too sure myself either." Rin said. "Though I have my suspicions."

"Oh?"

"Well, for one thing who is the most powerful magus in this city?"

"Point."

"And on another note," Rin said. "Caster is a magus herself. In fact, that's the defining trait of the class. And as magi, they qualify for Masters."

Shinji nodded after a moment's thought. "That's true," he said. "Though, that still leaves the question of where they got command spells from."

"Two possibilities," Rin said. "The first is that Caster was summoned early, before other Servants were, and the Grail granted her command spells among other would-be Masters."

"That's certainly possible." Shinji agreed. "And the other possibility?"

"Caster, being superior to any magus of the modern era, killed her Master as soon as or soon after she was summoned." Rin said coldly, and causing Shinji's eyes to widen in surprise. "And after their death, stole their command spells for her own."

"But, without a Master she…"

"Servants require a Master as a reliable source of prana." Rin interrupted. "But the Caster being magi themselves would know how to find alternative and reliable sources of prana on their own. Prana is after all, the key to all magic. Without it, we can't use our mysteries, and thus finding and getting it is a basic skill for magi."

"I see." Shinji said with narrowed eyes. "If the latter then, Caster is one dangerous enemy."

"And now we've challenged her." Rin said before shrugging. "Still, she seems content to let us back off with just a warning, if her actions immediately after the battle are any indication. If nothing else, it gives us time to prepare a new plan on how to deal with her. Grandfather does want her off the mountain after all."

Shinji nodded before stepping closer. "About that," he said. "We could just order Rider to blow the mountaintop off in a single shot."

"Tempting," Rin said. "But too dangerous for anything but as an ultimate last resort. Especially since a number of people live there. How Caster managed to get them to look away from her and such is academic, but the point is if we blow the mountaintop clear, those people would likely end up dead."

Rin leaned forward with narrowed eyes. "If that happened," she said. "At best we'd be prioritized by the other Masters, though they likely would get in each other's way. At worst, well, the Caster of the last war was so aggressive that the Overseer actually suspended the contest and put up a command spell as incentive for the Masters to focus against Caster."

Rin tilted her head. "The former will be a massive pain but it's workable." She said. "The latter is outright impossible to resolve."

Rin clenched her fists, but after a few moments she relaxed, and Shinji decided not to press the matter. "So," he said instead. "For now we should regroup our forces, apply what we've learned, and make new plans?"

Rin glanced back at Shinji after a moment, and then smiled. "Pretty much," she said, also while gesturing Shinji to come closer. He did as asked and with a curious expression on his face, only to be pulled into an embrace even as Rin lay down against her desk, her legs spread beneath Shinji.

"But that's for later." Rin whispered into her brother's ear. "Right now, I could use some stress relief."

Shinji swallowed dryly, his nose filled with Rin's scent, and his body heating up expectantly this close to his sister's body. "H-here?" he croaked.

"Haven't you had fantasies about doing it on my desk?"

Shinji didn't answer, instead setting himself to making said fantasies reality.

"How do you plan to deal with this development?"

"I have yet to make my mind up yet." Caster answered her Master as she returned to her sanctum. "Though, I am inclined to let it go…this time. If Rider's Master decides to let bygones be bygones, then there's no reason to abandon our strategy of the defensive until Berserker is defeated. But should Rider's Master decide to press the issue, then we must of course seize the initiative."

"I see." Souichirou Kuzuki said while stepping out of the darkness. "And what of that monster you captured?"

Caster smiled fondly at her Master. "I'm a magus too." She said. "While I'm not as obsessed with knowledge for its own sake like today's lesser breeds are, I too share their curiosity for arcane secrets."

Caster's expression turned stern. "In this time and age," she began. "Phantasmal Species should no longer exist in this World, and have gone beyond Humanity's reach within the Inner World. And yet those abominations were clearly chimeras, hybrids of mundane animals and one of the Phantasmal Species. But which ones? How? And what was done to them? Those questions among others need answering, and may affect our strategy especially against Rider and her Master."

"I see." Kuzuki said with a nod. "And Tohsaka and Emiya?"

Caster's first response was to deploy her magic sphere, focusing first on Rider's Master though she quickly changed the focus, having no interest in watching a pair of adolescents copulating, and focused on Sakura and Shirou instead. The former was helping an unconscious girl caught in one of Caster's prana-harvesting operations, while the latter was keeping an eye out while Sakura was busy.

"As I said before," she said. "Let the children play. Their interference is trivial, unless they actually decide to seriously challenge us. If they do, then we should put them in their place, Archer and Saber or not. Or indeed,"

Caster paused, smiling a smile as malicious as it was sultry. "It could be an opportunity to obtain better tools than those we already have." She said. "Maybe even replace them as well."

Kuzuki silently looked at his students for several moments, and then nodded slowly. "Very well," he said. "We'll do as you say."

"Yes, Souichirou-sama."

A/N

Medea is the strongest magus in the Fifth Holy Grail War…and Cu Chulainn comes a close second. It never gets really shown off, outside of his self-cremation in Unlimited Blade Works, but he's that good and knowledgeable in magecraft, specifically rune magic. Indeed, along with Berserker and Lancer, the other class Cu Chulainn is suited for is Caster.