Dark water envelops me as I tumble head over heels in a crashing swirl of water. Salty liquid fills my nose, and I barely manage to stop myself from coughing out all of my air supply. Finally, I manage to slow my frantic spinning, and the brine burns my eyes as I begin to look around. I can't see either of my companions, and my frantic telepathic shouts don't reach them - but they're Servants, so they should be fine, right? Worst case I can summon them with Command Spells, if I can just reach the surface - but what direction is up!? As the tumultuous ocean I've been dumped into tosses me to and fro, I desperately search for anything I can use to get my bearings-!
There. I squint as green light sears my irises. The sun, colored by the seawater between myself and the surface. Closing my eyes tight, I swim frantically towards the surface, in spite of the roiling current tossing me about.
My muscles hurt - stiff shoulders cramping up as I paddle forward, legs aching as I kick. And slowly, painfully, until I just can't take it anymore, my lungs burn as though someone had dropped hot coals in them. I'm going to die. I'm seriously gonna die. I'm probably drowning, I'm definitely drowning, because I'm drowning-!
My eyes shoot open as I shake off a bubbling sense of darkness in my gut. The light is close now, dazzling my eyes, and for just a second, hope rises in my gut. And then my eyes adjust to the light, and any hope I had of survival is snatched away.
It's not the sun. It's not the sun at all.
It's a monster. A formless mass of teeth and scales and eyes and feathers and tentacles and arms and legs and fins and wings, all bubbling and ever changing around one distinct centerpoint - a glowing green emblem, with a geometry vaguely reminiscent of a cross, or perhaps a sword. Carved upon an unchanging set of gray scales, far too uniform to match the rest of the creature.
That was what had deceived me. That light, acting like the lure of an anglerfish, had drawn me in, and now…
A few of its eyes train their sight upon me, though it doesn't last long, with each of those eyes popping like a soap bubble or splitting open into another mouth or turning inside-out to unfurl a flower-like radial cluster of tentacles. But it sees me. I know it sees me, and I can see it, and it can see me, and I can feel my brain boiling in my skull as this strange creature's image crawls into my eyes and pours hot coals into the space behind them.
I scream. I scream in terror, pain, and joy as I turn away and start to frantically paddle away from it. How horrifying. How horrifying. What fun. What fun. I can't breathe. I don't need to breathe. I just need to run, and run, and hide, and seek, and play, and die.
The beast squirms and roars and wails and giggles, and the noise makes my bones ache as my body tries to shake itself apart. And then, finally, mercifully, a half-dozen harpoons made of bone skewer my body, tear me to pieces, and drag my back into the gnashing mouths of the alien sea monster.
I see.
I understand.
The world was always thus.
The nautilus spirals endlessly outward. The universe spins and folds. The stars open their eyes.
Ph'nglui, Ph'nglui… The dead god dreams…
The Sunken Spiral Castle rises.
***
I scream and gurgle as salt water fills my lungs. My muscles spasm, and my limbs twist uncomfortably in the churning tide of this hellish ocean.
What was that? What was that? What was that what was that what was that?
I died. I'm sure I died.
With strange aeons, even death may die…
No, shut up. I shake my head, crushing that squirming spiral before it can take root in my brain again, ignoring the dull pain behind my eyes.
I had to have died, there's no other possibility- but in that case...
Why now? Why have I returned to now of all times!? I'm going to drown! Oi, Satella, what are you playing at here?
I'm going to drown. I'm going to drown. I already expended my air supply screaming, so it can't be helped. I don't even know which way is up. But I can see that light, and I know - drowning has to be better than experiencing that again.
So I swim, in the opposite direction of the monster, until the dark shapes crawling at the edge of my vision claim me entirely, and everything goes dark.
***
-And suddenly, I can breathe again. I'm alive. I'm still alive.
"Fou! Fou, kyu!"
Something licks my cheek, and the darkness slowly recedes.
I wake up to the feeling of scratchy cloth on my skin, the groaning of wood under stress, and the sound of waves. As my eyes slowly open, the flame-lit wooden room I find myself in rocks violently back and forth.
A boat. I'm on a boat. Groaning, I slowly sit up, my stomach churning. To my side, Fou prances happily as I rise.
"Oh, Senpai! You're awake! Thank goodness…" Says a familiar voice from my bedside.
"Y-yo, Mash-tan." I half groan through my pounding headache and churning stomach. "You managed to save me, huh?"
"Eh? Oh, no, that wasn't me, it was-" She scratches her cheek nervously, but interrupts herself. "Oh! Senpai, you need to bring Mordred here with a Command Spell! Right away! Prelati-kun said it takes some time for Servants to drown, but-!"
"S-she's still down in that hell!?" Shit, shit, shit! My first command spell flares to life. "Mordred, teleport into this room!"
In a flash of golden light, the knight appears next to us, coughing and sputtering, with her sword still gripped tightly in both hands. "So you guys... found a way to- gk! -reach the surface, huh? Thanks…kh! ...for the save…"
"'Finding a way to reach the surface' - it's a bit more complicated than that." Says a new face as he enters the room. He's a young boy, with white hair and fancy-looking clothes. I've never met him before, but nonetheless… there's something familiar about him. "Thanks to the unique properties of this ocean-"
My stomach swirls even more than the waves outside. "Uh, can we… delay the explanation a few minutes…? Or rather...c-can someone get me a bucket? ...I'm gonna puke." I say while heroically restraining my seasickness.
***
I soon find myself above deck, where an endless expanse of stars shines down on the vessel, providing ample light to see my way around.
The ship is one of those old three-masted things you see in pirate movies. The outer hull is painted black, with a red bottom peeking above the crashing waves every now and then. Of course, there's a very clear reason why I can see the outside of the ship so easily.
"Ugh… why did it... have to be the ocean? Seasickness... has always been a weakness of mine... you know?" I groan in-between dry heaves as I hang my head over the side of the boat. "Ghk… Can we go back to Chaldea… and choose a different singularity…? This one… is no good…"
"Haha! It's good you've still got the spirit to joke around, considering the situation!" The kid from before laughs and pats me on the back. "Here, I'll lend you a hand."
Suddenly, the rocking of the ship stops. All motion ceases, as if I'm standing on dry land. Slowly, the high-speed turbine in my stomach grinds to a halt, and finally I can breathe easily again. "...What?"
"It's a minor illusion, to fool your body into behaving the way it would on land." He says with a smirk and a self-satisfied nod. "I'm not much of a mage, but things like this are well within my wheelhouse, you see."
"...Why didn't you do that earlier? I've been at this for almost an hour, dammit!" I groan.
"Well, it's not like my illusions last forever. It's usually best to let people overcome their weaknesses on their own - because once this wears off, you'll go right back to how you were. Trying to drift through life by lying to yourself is pretty dangerous, right?" He explains, voice full of sincerity. I wonder if he's one of those childish-looking mentor types?
"...Who are you, anyway?"
He smiles and gives a small bow. "Caster class. Francois Prelati, a humble alchemist and cleric, at your service."
"Another Caster, huh…?" I mutter. I was kind of hoping it would be someone useful in a fight… not some priest I've never heard of.
"Prelati, huh…?" There's a sudden burst of movement, and suddenly the boy has been knocked to the ground, with Mordred's sword pointed at his throat. "Too bad for you, the throne gives us information on obscure bastards like you!"
"Wait, wait, Mordred, what's-!?" I start.
"Ahaha… well this was to be expected…" Prelati chuckles with a nervous smile, hands raised. "But, to be clear… I'm not looking to be your enemy, you know? If I wanted to deceive you, I'd have introduced myself as Paraclesus or something."
"Tch. Your intentions have nothing to do with it, bastard!" Mordred yells, and her eyes flick to me. "Master, this guy is the lackey of Gilles de Rais - in fact, by most accounts he's the reason that man went mad in the first place."
Gilles de Rais. We'd been provided info on him during the briefing, since he was alive at this time - a former friend of Jeanne d'Arc, who supposedly went mad later in life, and was convicted of murdering around 140 children in occult rituals. In that case, then…
I nod, and Mordred pushes her sword against Prelati's throat, drawing a trickle of blood. "Any last words, child-killer?"
"Wait, wait, wait! I'm innocent! I'm innocent! I didn't kill anyone!" He screams, waving his hands back and forth. "Gilles and I were exonerated posthumously in 1992! Or, well, Gilles was… I got left out because I wasn't important enough. But anyway! We didn't kill anyone! We were falsely accused, for political gain! Our confessions were extracted through torture, and they didn't find a piece of material evidence! None of that would hold up in a modern court!"
"...Shit, he's not wrong." Mordred mutters, pulling her sword back. "But still, if we want to be safe-!"
"Don't worry, don't worry! I'm not your enemy! I'm an ally of humanity! I've got friends, and family, and things I like to do! I don't want anything to do with incinerating all of human history!" The boy says with a nervous chuckle. "Here, just to prove it, I'll form a contract with you. If you think I'm a traitor, you can use your command spells to make me kill myself."
"...We do need allies." I mutter.
"So you believe me?" He says, relief flooding his face. "Thank goodness…"
"I'm not sure if I believe you. But if you're actually a monster, I'll figure you out eventually. So for now, consider our temporary contract sealed." I say, and my command seals give a pulse of light in response. "Anyway, can you get on with whatever explanation you were going to give earlier? We're supposed to be in France, right? So what the hell is all this?"
The boy sighs. "Well, to answer the last question first… it looks like we've been trapped in a Reality Marble."
"Not again! Oi, Mash, weren't the Coffins meant to prevent this exact situation!?" I yell. Still, that does explain why we can't reach Chaldea, and probably why my telepathy isn't working…
"Sorry, Senpai. The Coffins prevent interference during rayshift, but it looks like someone was waiting at our landing zone this time…" She sighs.
"It doesn't have much to do with the landing zone, unfortunately." Says Prelati. "I'm pretty sure our culprit used a Holy Grail to boost his range - as far as I can tell, this ocean has swallowed the entirety of France."
"Shit…" I mutter. "With how hard it is to get out of that ocean, every person in France has probably already-"
"Nope!" The Caster interjects. "In fact, it's impossible for living humans to drown in this ocean."
"...What?" What the hell is he talking about? I got lucky, but I almost drowned! Why would other people be any different?
"Well, this place is pretty complicated, so let me explain." He says with a smile, and then holds a finger up. "First - any living being that falls into the water and doesn't have a resistance to the effect will be turned into a sea creature until this space collapses."
"But I'm not a fish right now... wait, actually, I've resisted something similar before, haven't I?" I mutter to myself. The Archbishop of Lust's blood hadn't corrupted me the same way it did her other victims.
Prelati's smile widens. "Second - of those that resist the transmutation, only 'dreamers' can reach the surface. That is, if you fall unconscious, and are capable of dreaming, you'll naturally rise to the top. But since Servants can't dream…"
"Mordred sank… got it. So it was less that you rescued me, and more that I happened to float to the surface, huh?" I reply.
"That's right. And, the third and last important detail of this Reality Marble-!" Prelati exclaims, but then a booming voice interrupts him.
"The caster becomes the king of the sea fiends."
Clunk. Clunk. Clunk. His prosthetic leg thuds against the deck as he approaches us, descending from the wheelhouse. I can't see him clearly at first, since the only light right now is starlight, but soon he comes into view.
The first sight is a faintly smoldering red line, trailing down the side of his face, down his neck, all the way down his torso to his leg. As though someone had cut him in two and then smelted together the severed pieces.
The next few parts of him to become visible are all the same color - long white hair dancing in the air behind him, and a flowing white beard similarly wind tossed, as though his chin is alight with white fire. And below, a gleaming white ivory peg leg that he stands upon with practiced ease.
And finally, the rest of the man becomes visible - the man who can only be the captain of this ship. His bare, well-tanned chest has a level of muscle on par with Cu Chulainn, and despite his obvious age, he doesn't move with even a little bit of stiffness. Eyes closed, he takes a drag of the pipe in his left hand, and exhales calmly - and then, his eyes open, and for a moment I think I see fire pouring out of them.
"Captain! So you were listening after all! I almost died, you know? You could have said something." Prelati says with a sigh.
"Feh. Thou'rt a slimy type, so I had faith that thou wouldst squirm thy way out in some way or another." The captain scoffs.
"S-slimy!?"
"In any case…" He grumbles, eyes moving over each of our small group in turn. "Ye are the so-called Chaldeans, then?"
"...That's us. Where did you…?" Mash says, slightly shocked.
"From that little squid there." He says, nodding toward Prelati. "I neither know, nor care, where he learned of ye from. But ye had best impress me tomorrow, or I'll throw the lot of ye overboard."
""Tomorrow?"" Mash and I both ask.
"Aye. We'll begin our hunt for the bastard once the sun rises." He grins.
"...The 'king of the sea fiends' you mentioned?" says Mordred.
"Hah! Thou'st hit the nail on the head." He laughs coldly, and flame seems to leak from his eyes once more. "Who else could it be, but she? My eternal foe, the last sea monster. Aye, it'll be she for certain."
"My white whale."