In Her Misted Solitude, Round Birb Waits Napping
The HMS Cathuria, a pale white passenger ship of the Arisian navy, cruised smoothly southwards.
On the bridge, Princess Twilight Sparkle drew her heavy jacket tighter against the frigid air and resisted the urge to shiver. She'd been expecting the chill, of course, but this far from the equator, hundreds of miles beyond Mount Aris and approaching the very edge of standard Equestrian maps, no amount of thick clothing could protect a pony entirely. Not even an alicorn. Granted, she had all manner of spells that could banish the cold without difficulty. She could raise the entire ship to a comfortable warmth if she had to, but no - that wouldn't do. Her strength was better saved for more vital things.
To her left, a grim-faced hippogriff mariner turned one eye to the princess. He kept his attention on the ocean ahead, talons firmly on the ship's wheel, and spoke in a hushed voice. "Mists on the horizon. We'll take her no farther - help's too far if we run into trouble."
Twilight nodded, affording the hippogriff an optimistic smile that wasn't returned. "This'll do, Captain. I won't be long."
"Hmph. Something's not right with the waters. We'll turn around and drop anchor a few miles back north."
Twilight nodded, turning to vacate the Cathuria's bridge. Already the captain was shouting orders to turn the vessel around, which were echoed in turn by his officers and translated into action. Hippogriffs were generally friendlier in Twilight's experience, but these were professional sailors - a superstitious lot at the best of times, and not without reason. She had treated them with politeness and courtesy, trusting in their expertise at sea, and they had done likewise in return.
Stepping out onto the frostbitten boards of the ship's open deck, Twilight looked out to the horizon and faintly lit her horn. Flat, glassy water stretched in every direction; open ocean as far as the eye could see, and further still beyond. Mount Aris lay a week of sailing behind them - the spire at its tip had vanished from sight sometime on the second day. Now hundreds of miles lay between the Cathuria and anything that might be called civilization. The bright summer afternoon illuminated a fat lot of nothing. Out here, even the hippogriffs' potent ability to turn into seaponies was rendered moot. A darker but no less barren expanse than the open air stretched out below - uncharted depths in which only a madmare would dare try to dive.
Twilight braced her legs as the deck began to tilt, the hippogriffs skilfully maneuvering their ship into a smooth starboard turn. Her horn caught a faint whiff of magic on the air - too weak to affect anything by itself, but a useful confirmation that they were in the right place. She made a mental note to commend the captain later. By necessity he had been told very little of why his ship had been ordered out so far, but his instincts and experience had picked up on the change in the air immediately. True to the captain's word, she could see a dusting of mist faintly creeping over the horizon - a sign to turn back.
Twilight offered polite goodbyes to the nearest sailors and leapt from the ship's deck, spreading her wings wide and taking to the air in direction of the distant mistbank. The icy ocean offered little lift and, winter clothes weighing her down, the princess braced for a long flight.
The second leg of her journey - several hours of continuous flying - was hard going, but Twilight had become familiar with this routine and had prepared herself well. It taxed her body, certainly, but fell well within the abilities of a full-fledged alicorn. What lay before her was of much greater interest than aching muscles or chilly lungs.
The wall of mist, no longer a faint suggestion on the horizon, was thick and dense, vast in size, and spread lazily outwards in every visible direction from the clouds to the far peripherals of vision. A strip of solid land emerged from its base, hinting at the existence of a peninsula shrouded beneath, frosty and barren of even the hardiest life. Twilight lit her horn once again; this was the part she had needed to save her strength for.
In the princess' vision, the mist came alive with colour and motion. No mere spectacle of meteorology, the mist itself shone and coiled, glittering before her eyes, potent and raw. A billion shades of deep blue, lazily shifting and churning into and around themselves. The mist was not merely a lazy miasma of frigid air, but an untamed froth of power and potential - a vast nebula of magic held together only loosely by the law of attraction.
The hippogriffs, even in their ignorance, had been wise to turn their ship around.
Before her hooves had even touched the frozen earth at the edge of the mist, Twilight was fortifying herself with protective spells. Oblate Veil of Evocation Resistance came first, of course. An interlaced cast followed - Protecta Obscura, Ward of Enduring Reason and Energy Deflection - to protect her mind and body from arcane influences. With a flick of her horn the entire array of protective magic was wrapped in an Obstruction Charm, and then a Shield of Mystic Harmonization just to be certain. An unprotected creature would quickly fall under the magic's sway, and be subject to rapid and profound changes.
It had happened before.
Maintaining several spells at once would take some focus, but it was nothing she couldn't handle. Twilight strode confidently forward, trusting in the powers she'd honed over a lifetime of intense practice and study to protect her from unwanted effects. The wall of mist parted before her, as if reluctantly allowing the alicorn a small concession of personal space, and before long it surrounded her entirely, so dense that it became near-opaque. She held no fear of getting lost - really, her destination wouldn't be far no matter which direction she chose to go. Straight ahead was as good a choice as any. Despite the frigid environment, the interior of the mist itself was almost comfortably warm.
For a few minutes, the only sound was Twilight's hooves on the stony ground. Then, out from the cloudy air there loomed a shape: a seapony, or at least a statue of one, twice life size and rendered in an unusual, faintly shimmering metal. On its head, an intricate crown. On its face, a playful smile baring a fearsome array of pointed teeth. And along its body, the unmistakable and markedly exaggerated bulge of pregnancy. The entire thing glowed with the same strange magic as the mist that cloaked the region, tightly concentrated like a singular star amongst a clouded galaxy. She altered her course a little and gave the statue a wide berth; even so well shielded against magical effects, there was no point in pushing her luck.
As Twilight trotted onwards, further progress was complicated by more of the same. The area was littered with such statues, though they varied by size, detail and even state of completion. From tripping hazard statuettes barely the size of an apple, to effigies that loomed from the mist like grand gothic manors. From tasteful depictions of the subject in repose, her child-bearing state only lightly implied, to absurd near-spheres whose seapony features looked to have been tacked on as an afterthought. From intricate, finely crafted works that suggested painstaking hours of fine effort, to vague, haphazard abstractions that looked to have been abandoned half-forged or subjected to some postmodern whim. A few of the statues depicted their subject as a hippogriff, though each and every one represented the precise same mare - the same features, the same intricate crown, the same lethal-looking teeth. It was as if Twilight had stumbled into the yard of a lunatic artisan, whose every waking hour had been dedicated to iterating the same highly specific project, over and over and over again for a number of decades.
The statues, even potent with magic as they were, didn't bother the princess overmuch. They were simple reservoirs for raw mana, unusual only in number and scale. The magic itself - its true nature and ultimate origin - that, on the other hoof, was a mystery that made Twilight itch with curiosity. A curiosity she suppressed, and not for the first time, with some difficulty.
Twilight sensed that she was getting close to her destination; the persistent thrum of magic in the air grew more intense the further she got from the shore. Even so, the final leg of her long walk was slow going. Between the poor visibility and the frustrating tendency for the statues to block her path entirely as if arranged to do so (grinning prankishly at all times), the princess often found herself needing to take lengthy detours. Sometimes minutes were wasted retracing her steps. Time, though not immediately pressing, was a concern here - even fortified as they were her magical defenses would only hold up for so long, and falling under the effects of the raw, uncontrolled power that saturated this place would be problematic in the extreme.
Twilight shook her head. She could have sworn that one of the statues grinned extra widely as she passed by. With a steadying breath, she forged onwards.
At last, with a faint smile of relief, Twilight reached the center of the proverbial storm. A shape loomed out of the deep mist, the first landmark she'd come across that wasn't a statue. It was tremendous in size, a stony-looking edifice that curved down towards her from the near distance and tapered to a broad point. Had it not been for the thing's unnaturally uniform shape and smoothness it might have been mistaken for the lip of a rocky outcrop. Indeed, deep shadows rising high into the mist beyond suggested that she'd reached the foot of a mountain range.
Twilight, setting her hooves and steadying her thoughts, knew better. She stood before the very tip of a single gargantuan claw.
Bigger than last time, intuition informed her.
Setting her hooves, Twilight raised her horn and lit it up. Channeling the simplest of all possible spells, the slow build of her own magic caused it to steadily brighten until it shone like a lighthouse beacon in the haze, shades of purple glinting and refracting as they penetrated the enchanted space with colour. Somewhere in the distance there was a faint, indistinct sound. Then a distant rumbling, steadily growing as the presence of her enchanted light stirred something - something immense - from beyond the wall of sleep.
The mist began to shift, drifting lazily away from Princess Twilight as if caught on an invisible wind. Slowly at first, reluctantly even, it thinned and crept away, expanding the princess' field of vision. She looked up, bracing herself.
Marinia was always quite a sight.
As the mists receded, gradually but with mounting speed, a second giant claw emerged into view - then a third, and then a full taloned hand, avian and primordial, absurdly large. The princess would barely have registered as an insect had she dared to climb into its palm. Beyond, a proportionately vast forelimb seemed to stretch into the middle distance, clad in long, angular feathers of deep midnight blue. Then a beaked, sleeping face, nestled between the nearer limb and a newly-visible second in a state of comfortable repose. An eye, like a great cathedral window rendered in sapphire, slowly eased partway open, and as the entire vast being shifted slowly into wakefulness the fog retreated ever faster, spilling away and dissipating. Twilight stood before a slumbering hippogriff - the same one depicted in myriad statues - who pulverized the clouds high above through the mere act of raising her head to stretch her long neck and cast off sleep. A deep, reverberating yawn shook the very ground, and revealed that the statues' pointed teeth were no artistic exaggeration.
Indeed, even the most detailed icons Twilight had just passed by were a pale imitation of the real thing. A hippogriff, yes - but in this case the word was merely insufficient. Aside from her gargantuan scale, such that she had come to use almost the entirety of this antarctic peninsula as a sleeping spot, smaller details stood out in the flesh. The bony spines that emerged here and there from her feathers, the hadalic depth of her eyes, the ornate silvery crown - an edifice all its own of winding, pointed metal - that glistened like frosted silver and seemed to emerge smoothly from her brow rather than resting upon it. A thick, curly and poorly kept mane of dark amethyst spilled from her scalp, flooding down her shoulders to settle loosely on the ground a dizzying distance below. Everything about her, down to the most mundane details, was subtly uncanny in ways Twilight struggled to categorize.
This was no true hippogriff. Not entirely. Not any more.
There was, of course, one detail that the statues had not failed to capture. The mist swept back, quickly now, upwards and around, thinning out, to display the absolute enormity of her midsection. Marinia lay unashamedly on her side, but no pose could have concealed the vast and fecund shape of her belly, which rose into the air from its settled position and all but generated its own localized horizon line. Even a hippogriff of normal size - with legs like stilts compared to those of a pony - would have struggled to stand in such a state, as much brood-filled womb as anything else. In this case, the brute reality of scale transformed an implausibly oversized pregnancy into an outright geological feature, garbed in its own rolling forest of fine feathers. Somewhere, Twilight knew, hundreds or perhaps thousands of meters distant, were great wings, long hooved legs, a tail, and - logically - quite the impressive set of hindquarters. But with such an obstruction there was no hope of her seeing them at this angle; not without another few hours' travel.
Where the mist had glittered with loosely coherent power and the statues had glowed like muted stars, through Twilight's magic detection every part of Marinia's body shone so brightly that attempting to hold a face to face conversation would be like staring directly into the sun.
The princess averted her eyes, dismissing the spell. She looked back - and up (very, very up) - and saw that Marinia was looking down at her with the subdued smile of someone who had woken to a mild but pleasant surprise. When the hippogriff spoke, she did so in a voice just as deep, just as distant, but thankfully not quite as cold as the ocean floor. "Princess Twilight Sparkle," she said, visibly holding back a second yawn. "Good morning."
This was, perhaps, the very strangest friendship Twilight had forged since her coronation.
In truth, Twilight understood very little about Marinia. The slim knowledge that she'd scraped together from observation, research and the occasional conversation offered more questions than concrete answers. Records on Mount Aris confirmed that she had once been an ordinary hippogriff prior to the Storm King's invasion, but most had been lost in the exodus to Seaquestria and what little remained was piecemeal and obscure. Since then she had disappeared, then come into contact with something potently magical, sufficient to dramatically transform her - but when, how and for what purpose?
Princess Skystar had met her first, a few years after the hippogriffs returned to Aris. At something of a loss for what to do with her strange new acquaintance, she had contacted Princess Twilight. And thus Twilight had taken the muddled role of friend, confidant and - occasionally - tutor in the ethical handling of magic. Few others knew that she existed, or where either of the princesses occasionally went when it came time to cryptically 'visit someone'.
Whenever she left the ocean for any prolonged length of time, in her preferred seapony form or otherwise, excess mana would spill from Marinia's body, largely in the form of mist. The magic suffusing her, though clearly very inclined to prompt spontaenous fertility and growth on incredible scales, was unclear in origin and stubbornly defied study. Then there was the question of children. This certainly wasn't Marinia's first pregnancy, though at least in Twilight's memory it was a strong contender for her largest. Where in Equestria could such vast creatures live in any great number? And what of their father - was there even one to begin with, or were Marinia's pregnancies simply a recurring symptom of the power contained within her?
The closest point of reference Twilight could think of was an occasional quirk of talented young unicorns. With magic developing faster than their bodies could keep up, and without the practice or discipline to properly channel it, they could sometimes release powerful spells entirely by accident. She'd suffered several periods of similar instability in her own foalhood, mostly kept in check by Princess Celestia's wise tutelage. But a young unicorn's magic would only surge sporadically, and in ways that were effectively random. Marinia, on the other hoof, was obviously no unicorn, certainly no child, and as best Twilight could tell, had settled into a continuous, almost stable state of magical overload for at least the past few months.
So it's like, some kind of supercharged... eldritch puberty? she had wondered. Not that she'd ever suggest such a thing out loud.
For her part, Marinia would always flatly refuse to talk about herself - her past, her everyday habits, her relation to other beings in the ocean, the source of her magic, her family and the question of whether she even had one. Twilight might have been a scholarly mare, driven by intense curiosity and an earnest lust for knowledge more often than was practical, but Marinia was reclusive and almost obsessively introverted. The years had taught the princess to occasionally take 'no' for an answer - especially from someone that made Dragon Lord Torch look only somewhat large. When Marinia did open up she would ask after recent news and the health of the few people that knew her, or discuss abstract philosophical or conceptual subjects with no apparent motive.
Compromising, Twilight had made it her mission to befriend this unusual being. Understanding, she well knew, is a thing that can be earned through trust - and as she'd learned from the strange case of Starlight Glimmer, it's always better to have the friendship of immensely powerful, potentially dangerous creatures than not. Thus, she had made a habit of visiting Marinia on the rare occasions that she ventured out from the depths of the ocean.
Today, however, was no casual social call. Today was special.
"What brings you out here?" Marinia asked, idly stretching her claws and settling her incredible weight with practiced gentleness.
"Well," Twilight began, "I found out that-"
"Wait." Marinia cut her off in a frustrated tone. "Oh no. Did something happen again?"
Twilight smiled. "No, no unexpected encounters this time."
Marinia sighed gently, visibly relaxing. "Good, good. How is- what was her name again?"
"Silverstream," Twilight answered.
"Mmm." Marinia mumbled, allowed herself to be distracted for a moment. The ornate metal headpiece upon her brow glowed faintly in shimmering blue-black, one of the multitude of statues floating out of the mist in a sheath of telekinesis. Twilight watched, biting her lip to keep herself from asking the obvious question. The statue was a crude, barely recognizable as a seapony at all let alone a specific one.
The vast hippogriff studied the statue closely for a moment, her magic flaring momentarily, feeding into it, forcing the metal to swell and flow and reshape like liquid glass. It eventually settled on a closer approximation of Marinia's current appearance: lounging, half-awake, immense. The statues had been something the pair of them came up with together - a way for Marinia to harmlessly vent and store some of her excess magic. To the princess' trained eye, the powers on display were immense - far more so than their owner could wield with any level of grace, and even casual practice in their use would ultimately be helpful. Setting the statue back down somewhere behind her, Marinia smiled and re-railed the conversation. "...I'm sorry. And how is Silverstream now?"
"She's getting on well all things considered," Twilight said. "The foals arrived healthy, and it's taken a few months but I've managed to gradually ease off most of everyone's excess, um, size with regular dispels."
"Most of it?"
"She... might still struggle with doorways for a bit." Not that Silverstream or Gallus seem to mind that particular inconvenience, Twilight thought.
Marinia smiled faintly. "...that's good. I still have no idea how that one little idol wound up so far astray. It's like they have minds of their own sometimes - but don't worry, I've been keeping them all very close."
Twilight was a moment away from pointing out that it was technically impossible for inanimate mana reservoirs to act on their own volition, but reconsidered; lecturing Marinia on the finer points of magic wasn't on the agenda for today. She settled for rolling her eyes. "Aaaanyway," Twilight mumbled, turning back to Marinia's pointedly polite smile high above, "I actually came to give you something."
"Oh?" Marinia asked, craning her neck to watch the princess more closely. "And what would that be?"
Twilight closed her eyes, concentrating her magic. Teleportation was something she'd mastered some time ago, but teleporting something other than herself - at a distance, and at scale - took an investment of focus and exertion. Several seconds of spellweaving later, through magic so strong that only an alicorn could safely wield it, a sharp pop heralded the appearance of... a pink cupcake.
This was no ordinary cupcake, of course. This was a work of art - from the subtle sheen of its thick, buttery pastel frosting and the fine, perfectly uniform vanilla base, to the warm, inviting aroma that immediately spilled out into the air - hovering there in Twilight's magic it looked and smelled like the very incarnation of delectable treats. It was also the size of a warehouse.
Twilight smiled brightly, a bead of sweat running down her face as she worked to keep the mountain of confectionary madness aloft. "Happy birthday!"
Marinia blinked, her beak hanging open slightly. For a few seconds, the enormous hippogriff was at a loss for words, deeply surprised. Eventually she raised a colossal claw to her breast, leaning forward thoughtfully. "It's... is it? How did you find that out?"
Twilight smiled nervously, not sure whether the hippogriff might be offended or touched by the breach of her usual secrecy. "Well..."
Pinkie Pie had marched - not bounced, marched - into Canterlot Castle's throne room like a mare on a mission, heralded by a blast of very dramatic paper streamers.
"Twilight," she had cried, "I need fifty thousand tons of wheat flour! I'll take Canterlot's entire stock! It's an XK-class red alert all hooves on deck party emergency! Baking requirements at unsafe levels!"
Pinkie hadn't been this fixated on anything party-related since Silverstream's 21-Confetti Cannon Salute Super Short Notice Foal Shower. Twilight, caught mid-sentence in a discussion with Spike, had turned to her pink friend with a look of restrained, patient confusion. "Pinkie, I-"
"I've cleared my social calendar - I have to cook! The hour draws close! Iä! Iä! Cupcakes ftaghn, Twilight!"
Twilight and Spike had shared a look, then responded simultaneously. "Huh?"
"There was no stopping her," Twilight explained, "but given the size she was aiming at, there weren't many people it could be for. I checked in with Princess Skystar, and by chance she'd come across census records from before - well, before the Storm King attacked Mount Aris. Your name was there, and sure enough so was your birthday." She paused, smiling nervously. "...I don't think Pinkie even knows you exist. She has a sense for things like this."
There was a long, pregnant silence (not quite as pregnant as Marinia; few things could claim that honor). The massive hippogriff was visibly conflicted, her face a battlefield of emotion. Just as Twilight began to suspect she'd crossed a line, the expression looming above settled at last on 'deeply touched,' with the faintest hints of a blush.
Marinia sighed gently. "I haven't spared much thought of those days for a long time, Twilight. There are things better forgotten, and the young princess should be careful what secrets she looks for. But... thank you. It's very thoughtful."
Twilight's response was drowned out by a deep, distant rumble that could only be a certain very large stomach voicing agreement. Marinia was definitely blushing now.
"You're welcome," Twilight said after the noise faded, passing the oversized cupcake from her telekinesis into Marinia's with no small feeling of relief. "Pinkie's rarely wrong - though to be honest I don't even know what you usually eat."
Marinia smiled widely - the same jagged, playful grin worn by her multitude of statues, only accentuated by the fact that her actual teeth were far larger and quite evidently real. "Maybe one day you'll see." She levitated the cupcake closer to her face, pondering it for a moment. "I'm not sure what I've done to deserve generosity like this - and it's been years since I've eaten anything with sugar, but it does smell very nice..."
Twilight politely averted her eyes, unwilling to find out whether her gift was small enough to go down in just one bite. Elsewhere in the world, at that very moment, a certain pink pony observed a moment of silence as her greatest creation met its grisly fate.
The princess took a moment to take stock. She double-checked her magical defenses and found them to be in good order; more taxed than expected, but steady enough to hold a conversation and then get back to the shore at a brisk pace. With the mist largely gone, she'd be able to fly back. The barren, frosty wasteland the hippogriff had chosen as her sleeping spot was now revealed almost in full - studded in every direction with the multitude of statues that Twilight had passed by, and thousands more besides. It was impossible to shake the feeling that all of them had turned subtly in place, watching her with a myriad copies of that same cheshire grin. Since when had there been so many? Were the nearest ones... closer? Arranged to block the path she'd taken? Surely not.
A deep rumble drew her attention back to the birthday girl; Marinia had made short work of her gift, and rolled more fully onto her side to rub her tremendous midsection. For just a moment, the air rippled unnaturally, the vast expanse of lightly feathered womb quivering with internal movement for a matter of seconds until her roving talons soothed it back to stillness.
With a lazy heave of her wings - their sheer span briefly eclipsing her gravid form - Marinia righted herself and smiled down at Twilight once again. The 'impossibly large eldritch being' aesthetic was somewhat marred by the pink frosting splattering her beak.
Marinia paused for a moment to lick up what had missed her mouth; the tongue that danced carefully between her jagged teeth was far too long to be proportionate. "Let your friend know that her efforts are... appreciated," she commented eventually. "By more than just me."
Twilight smiled politely, but her mind was racing.
What in Equestria is she?
What's growing inside her?
Should I ask?
Would that offend?
How is she so calm?
Why am I so nervous?
Questions - thousands of them - danced furiously on the tip of the princess' tongue, bubbling up from her subconscious but not quite audacious enough to actually leave her mouth. Her hooves - no, her whole body, tingled faintly. With a small shiver, she realized that she was sweating, a wave of panic running through her. This wasn't like her. Intrusive thoughts, faint tingling, a feeling of unnatural warmth; these were the exact symptoms Silverstream had described before she became the center of an earthshaking incident.
Had her protective spells failed? No, she'd just double-checked. She went ahead and triple-checked just to be certain and found them all still in place. Had she left herself vulnerable while teleporting the cupcake? No, definitely not. Could the raw magic Marinia radiated be bleeding through her layers of protection by sheer volume and pressure? No - that's not how magic works.
Twilight gulped. Perhaps leaning on her own understanding of how magic works, great as it was, had been a mistake.
"Princess?" Marinia asked, leaning her vast body forward in a show of restrained concern. Her voice was even more distant than usual, muted as if receding somewhere far away.
Twilight swayed, suddenly unsteady on her hooves. In a moment of clarity, she lit her horn. She could purge the influence before it took hold. She could fortify her defensive spells. She could teleport hundreds of miles away. She could-
-she could see it now.
Letting go - giving in, dismissing her magical defenses and letting Marinia's strange influence flow into her. It would be so simple.
Silverstream had described a sort of fuzzy, pleasant tingling slowly filling up her body before changes began. A gradual onset of pleasant feelings that intensified until they became all-consuming. But she'd only been exposed to a single tiny statuette, and only for a short time. How intense, how disgustingly indulgent it would be to bathe in the power of hundreds of them at once, in the presence of their very source!
She'd gasp in shock and sudden pleasure as immediate changes seized her body - the sudden and rapid development of her own foal - her own brood of foals. Her belly would bulge aggressively, round and wide, bursting her winter clothes into rags. She'd stumble to the ground as her center of gravity shifted, only to find that ground further and further away as she gained meters of height by the second, all to barely keep up with the overclocked baby factory at her core.
She'd roll onto her side and see Marinia watching her with glowing approval - with more than that. With each passing second Twilight would draw closer to her without moving, purely by growing into new space. She'd shiver and whine as her teats ballooned impossibly, her belly button inverted with a sharp pop, and thick veins raised here and there to the surface of her sides, merely implying the great pressure within. The kicking and writhing of healthy foals would animate her entire midsection with signs of life abundant, sparking feelings of pleasure and fulfilment beyond her wildest dreams. She'd find herself rivalling the hippogriff in scale within minutes, sprawling across the peninsula as a living icon of alicorn fertility, her growing body tumbling enchanted statues aside like so many discarded toys, crushing out a comfortable new valley in which to recline. She'd find herself scraping the upper sky while casually lying down, and in a moment of impulse she'd reach for Marinia and find only the passionate, hungry welcome of someone desperate for a peer in carnal need.
What secrets would Marinia reveal in furtive whispers as hooves slid though her messy mane, a tongue traced the valleys of her swan-like neck, or an impossibly fecund purple womb ground belligerently against her own midnight blue swell, each motion and mutual sensation seismic in magnitude? How would it feel for the hippogriff's eager, searching claws to trace lines down Twilight's stretched and bulging sides, to squeeze and rub and play and seek ever more sensitive places?
They'd turn the peninsula into their own shared bed, one woefully inadequate for two creatures as colossal as they, and be forced to find ever more creative ways to straddle and embrace one another without risk of tumbling into the sea.
And then she'd silence Marinia's whispered confessions with her muzzle; a torrent of breathless nothings and unspoken requests for more of everything, lips overwhelming the trembling beak heedless of pointed teeth. Eventually she'd lean back, moaning in unbridled lust, shuddering at the raw sensations of their mutual enormity, and whisper-
"-nononono waitwait WAIT!" Twilight cried, her horn erupting in a desperate blast of purple light. Renewing and enhancing her magical protections hastily and with great effort, the princess halted the effects of Marinia's ambient magic through sheer brute force. Aside from persistent feelings of warm tingling and a deep, uncomfortable sense of yearning emptiness, nothing had changed. She was still the slim, normal-sized alicorn she had been when she arrived, shrouded in Marinia's gargantuan shadow. But it felt like treading water against a current - like at any moment her concentration would crack, her composure would shatter, and the transformative powers saturating this place would flood in and claim her.
Marinia clicked her talons sharply, and Twilight felt the unnatural urges and sensations began to recede. The libidinous feelings remained, but the magic hadn't taken hold. Not quite. Not entirely. It clung to her, reluctant to let go, but it felt like a great pressure had been lifted away. How or why was beyond her, but she met the change with no small amount of relief.
Marinia smiled politely at something, though Twilight couldn't be sure what, and murmured, "...thank you, Beau."
Who in Equestria is Beau? Twilight wondered in a haze, focused on the difficult endeavor of forcing her hind legs to stop shaking. Marinia might have been trying to keep that part quiet - but quietness is a tall order when you're the size of a mountain range.
"Looks like our time's up," Marinia said wistfully, looking back down at Twilight. "I should go. It would be a shame to - ahem - inconvenience you any further."
Twilight blinked slowly, still collecting herself. Marinia should go? The princess had expected to leave of her own accord when her magical protection began to weaken, letting the bizarre hippogriff return to her nap. By all appearances she was too pregnant to stand; where would she even-?
Marinia was changing. Twilight gawped, suddenly at a loss for words. At first glance the gargantuan hippogriff seemed to be softening, blurring at the edges, but that wasn't the extent of it. With a start she realized that Marinia's headpiece - her 'horn' for want of a better term - wasn't glowing. This wasn't her doing. This was something else.
It was a strange and disturbing thing to watch; Marinia lay in perfect stillness, eyes closed, apparently indifferent to whatever was happening. It was as if she was radiating a haze of unfelt heat, a desert mirage that blurred her silhouette into a vague suggestion, but at the same time failed to conceal that things were shifting and changing shape. Twilight, staring in confusion, suddenly caught on - Marinia was changing from a hippogriff into a seapony. But she had no pearl shard with which to transform, and this process was no smooth, clean flash of light. It was both fascinating and revolting to see claws becoming fins, wings flattening, extending and becoming translucent, a beak shifting uncomfortably into a muzzle, a mane melding into a long frill, feathers and fur melding into smooth, seamless skin. Marinia's unseen hindlegs soon revealed themselves, now a long and powerful-looking tail that emerged smoothly from her rotund body and curved upwards into the air as she stretched and tested the muscles.
As she returned to solid corporeality, Marinia let out a slow, satisfied breath and gave Twilight a small smile. "That's better."
For a moment, Twilight even forgot that she was still shaking off the intoxicating aftereffects of her near miss. Marinia's seapony form was something she hadn't seen before - that had been a privilege reserved for Princess Skystar. It was quite the sight.
Quite aside from the lingering details - the immense size, the great swell of her heavily pregnant abdomen, the glistening headpiece and the monstrous teeth, there were strangenesses to it all. The proportions were still subtly wrong, but even out of water she held herself with a newfound poise and sense of comfort that hadn't been present as a hippogriff. Every fin and fluke, from the small, flexible ones that took the place of 'hooves' to the tremendous sky-scraping sails that had replaced her wings, bore ridges and gullies in wild, intricate, crisscrossing patterns. It was as if they'd as if they'd been decorated by an engraver or tattooist with incredible psychedelic dreams - and the attention span of a goldfish.
Marinia tested her jaw carefully before speaking. "We'll have to talk again when I'm a little less effervescent. It's better for everyone if you return home in the state you left." She paused for a moment, then gave that toothy, mischievous, 'could bite the average castle in half' smile. "And... sane. That helps."
"Th-thanks," Twilight mumbled, still trying to comprehend what was happening. This was supposed to be a simple birthday visit, but it was starting to feel that the price of admission was having her preconceptions thoroughly scrambled.
And then Marinia was moving. With her forelegs and tail, she heaved her vast form past the princess at a respectable distance, towards the ocean. Even burdened as she was, sheer size meant the trip was a short one. It was like watching an iceberg - a round, midnight blue iceberg without a single sharp edge - slide smoothly across an ocean shelf. Hundreds of meters in a matter of seconds.
"Take care, Princess," Marinia said, glancing over her shoulder. "The gift was lovely. And now that we know it's my birthday, you're not the only one interested in treating me..." And with that she leaned forward and plunged into the water, disappearing with barely a splash. Moments later, the myriad statues were wrapped in blue-black magic and followed her, a great metallic cloud rising, turning, then likewise disappearing into the distant ocean. The last dregs of the mist faded into nothing.
Twilight was left to her own devices on the barren antarctic peninsula, the frosted ground wiped entirely clean of sign that anything had been here to begin with, the early evening sky cloudless and clear.
Exhausted, confused, sweating profusely and still irrationally, frustratingly horny in the magic's minor but stubbornly lingering influence, Twilight stared into the middle distance and said "...what."
The captain of the HMS Cathuria yawned softly, preparing to turn his ship over to the night shift and retire to his quarters. Ever since Princess Twilight had departed on her secretive errand, nothing of note had happened. Aside from the brief sighting of a mistbank on the distant horizon, both sea and sky had been serene and placid for the entire afternoon. They had retreated a few miles as stated, dropped anchor, and settled in for a relaxed, if chilly afternoon as they awaited her return. Some of the crew had taken to fishing; others had sequestered themselves in the mess or on the deck to gossip or play cards or practice their knots, and this eased his earlier nervousness. As for Princess Twilight - the hippogriff mariner spared little curiosity for the purple pony's business. Princess Skystar herself had commissioned his vessel for this errand, and fulfilling his duty to the crown of Aris was satisfaction enough.
With a mug of hot coffee in hand, he stepped out onto the deck and into the deep chill of impending night. The princess wasn't expected to return until the morning; this was a final cursory tour of the ship to ensure that the shift was transferring smoothly.
...so he was quite shocked when Princess Twilight all but fell out of the sky, landing hard in the center of the deck with her wings and hooves spread wide, taking deep, labored breaths on the verge of hyperventilation. Her horn sparked and fizzled lamely, powers on the verge of exhaustion.
Hippogriff sailors turned to stare, some exclaiming, others muttering amongst themselves. The princess' usual grace and poise were nowhere to be seen; she was sweaty, dishevelled, her winter clothes loose and unkempt, her mane wild. For a few seconds, her heavy breathing was the only sound, until the moment of shock wore off and the captain stepped forward.
"Holy carp, Princess! Are you hurt? Do you need help?"
Twilight met his gaze, and for a moment he was taken aback. The bags under her eyes and shrunken pupils suggested that she was brutally tired, but there was also a focus there - a sort of twitchy, primal neediness he'd seen in very few creatures before. Then, after a pause, the stare broke. The princess stood upright, regaining the faintest modicum of dignity. She ruffled her wings and awkwardly folded them, tail twitching on a hair trigger.
"Ngh - no, no, I'm fine," Twilight said, clearly forcing composure upon herself. "Could you send the girthiest willing stallion aboard to my quarters-" She paused, biting her lip self-consciously. "-and give us a few hours of privacy? I have some... feelings to work out."
The captain was too confused to object.
So preoccupied were the hippogriffs by Princess Twilight's bizarrely randy shift in mood, that none of them noticed an immense shadow pass silently through the water beneath the Cathuria. A jagged grin flashed playfully up at them from beneath the dark water, before vanishing once again into the unfathomable depths of the sea.
Author's Note
This story in particular was based on the following picture, by Carnifex. 
Sharp-eyed readers may have encountered Marinia before - she's been around for years, mostly in the form of notes that I never got around to doing anything substantial with. Klamnei and I hashed out the concept together, and while I'd tentatively call her "my" character it's impossible to understate how important his influence, input and ideas have been, particularly in commissioning artwork and coming up with fun scenarios. Finally she makes an appearance in writing, and now that art has a little bit of context behind it!
Go take a look on Derpibooru if you wish, and please give Klam and the relevant artists due praise if you like what you see.
