Chapter Text
The abyss was never meant for their kind. Every mermaid knew the ancient warnings told by the elders: the deep trenches were a graveyard for spirits, a place where the crushing void swallowed both magic and spark. But curiosity had always burned brighter in Orion's spark than caution had grabbed him, pulling him past the safety of the sunlit shoals.
How long had he been wandering this abyssal kelp forest? Down here, time was just a current that went nowhere. The endless dark would have been a lonely place, but Orion kept a soft, cyan light spell continuously glowing in his palms just to navigate the towering, iron-thick stalks. Even though his immortal frame wouldn't simply shut down from the depths, his spark ached for the surface. It was a heavy longing for the crisp taste of air and the vast, open sky.
He was drifting through the silence when a deep, rhythmic vibration disturbed the water. It was a violent struggle that sent shockwaves through the dense forest, throwing off Orion’s steady swims.
The mermaid swam cautiously toward the disturbance, raising his glowing hands to pierce the gloom.
The cyan light washed over a massive silhouette tangled in the thicket.
Orion's vents hitched in surprise. It was another mermaid. A breathtakingly enormous one, easily twice Orion’s size, with armor that gleamed like polished platinum.
Small, glowing white pearls were slipping steadily from the stranger's lower abdomen, drifting silently away into the black water. The poor mermaid must be so in distress they began to weep pearls out of their bodies, although it was odd for pearls to emerge down there.
"Hold still," Orion called out, his melodic voice swallowed instantly by the heavy pressure. "You are only pulling the vines tighter."
The massive mermaid froze. Two crimson optics snapped through the darkness, locking onto Orion. He hovered in the water, his heavy tail fin giving a slow, powerful side-to-side sweep to hold his position against the snare.
"I am not asking for an audience," the stranger rumbled, a furious growls. "Go away, little fish, before I tear this whole kelp down alongside you!"
"If you thrash any harder, you will tear your own fins," Orion said softly. He swam closer, undeterred by the hostility. "My name is Orion by the way. Allow me to help you."
The stranger let out a bubbling scoff. "You? You are half my size. What are you going to do, chew through the—"
Orion pushed his hands forward, flaring his magic. The cyan light bloomed brilliantly, warming the freezing current. In a single, seamless motion, the iron-tough kelp withered and uncoiled, dropping the massive frame free into the open water.
The stranger righted himself, shaking off the dead leaves. He stared at Orion’s glowing hands in utter bewilderment, as if he had never seen magic before. He drifted closer, displacing a massive amount of water that pushed heavily against Orion’s chest.
"What in the depths was that?" the stranger demanded, his crimson optics wide. He looked Orion up and down, clearly baffled. "And why do you swim like that, are you ill?"
"I am just weary," Orion admitted, letting the light spell dim slightly. "I ventured too deep, and I have been trying to find the current back to Atlantis. I need to reach the surface again."
The stranger tilted his massive helm. "The surface?" he repeated, sounding genuinely perplexed. "Why would you want to go up there? The pressure change would crush your optics."
"Because I need it," Orion said, his own confusion mounting at the other mermaid's absolute ignorance of the world above.
The massive stranger stared at him for a long, silent moment. Without warning, he leaned forward. His sharp dentae caught the delicate edge of Orion's fin, delivering a firm, quick nip.
Orion gasped, jolting backward in the water, his servos flying to his fin. "What was that for?!"
"My gesture of gratitude," the stranger grunted, though he looked deeply offended that Orion had pulled away. He tasted his glossa, a faint flicker of puzzlement crossing his sharp features. "You helped me escape this forest snare, even if your processor is clearly malfunctioning... Anyway, I shall reciprocate myself, my name is Megatronus. "
"I am not malfunctioning, Megatrous," Orion huffed, his rhythmic tail beats steadying his posture once more. "I just need to find the way back up to Atlantis."
Megatronus let out a heavy sigh. "You are not going to survive a swim to the surface right now. The dark is full of things much hungrier than me, and you are exhausted. You need shelter, I will show you one."
"Where?"
"My den," Megatronus stated, gesturing with a sweep of his arm into the black expanse. "It is close. You can rest there, gather your strength, and then you can try to find your 'Atlantis.' Come on."
"You mean your house?" Orion doubted.
"Yes." Megatronus looked at him with deadpan optics.
Orion hesitated. The stranger’s rough manners were abrasive, but the immense weight of the abyss had been pressing on Orion for far too long. The offer of temporary safety in the unforgiving void, especially with another of his kind, was simply too vital to refuse.
"Alright," Orion finally nodded, falling into the wake of the other. "Lead the way.”
The journey to the den was a silent one, measured only by the heavy, sweeping displacement of water from Megatronus’s massive tail. Orion followed in his wake, relying on the mermaid's sheer size to part the crushing dark of the kelp forest.
"We are here," Megatronus rumbled, his voice vibrating through the thick water.
He pushed aside a dense curtain of kelpie vines, revealing a hollowed-out cavern in the side of a deep-sea trench.
Orion drifted inside, his vents hitching. He was surprised to find out the entire cavern floor was blanketed in millions of glowing, perfectly round white pearls. They bathed the dark stone in a soft, ethereal light, swirling like galaxies trapped beneath the sea. The sheer beauty of it made Orion’s spark ache.
"Stars," Orion breathed, his voice a melodic hum of pure awe. "You have a million stars in your home."
"They are not stars," Megatronus said. The rough hostility was gone from his voice, replaced by a deep, crushing sorrow. He drifted over the glowing bed. "And their light is fading."
Orion swam closer, lowering himself to inspect the nearest cluster. He was so mesmerized by the delicate glow that he almost didn't register what the pearls were resting against in the center of the cavern.
It was a mountain of dark, jagged metal.
Orion’s optics adjusted.
Barnacles clung to the rusted joints, but the shape was unmistakable.
It was a mech.
A violent, primal instinct seized Orion’s spark, it was a terror older than Atlantis itself. Every mermaid knew the horror stories. Mechs were the unhinged predators that hunted their kind, draining their vital fluids to keep mechs' own frames from rusting away.
The mermaid scrambled backward, his tail thrashing frantically as he pressed his back hard against the rough cavern wall.
"Orion?" Megatronus turned, his crimson optics narrowing. "What are you doing?"
"Mech!" Orion gasped, pointing a trembling servo at the corpse. He looked frantically at the cavern entrance, expecting shadows to detach themselves from the kelp. "There is a mech here! We have to leave. If there is a corpse, a hunting party could be nearby—"
"Are you out of your processor?" Megatronus interrupted, his heavy voice echoing in the enclosed space. He swam smoothly toward the rusted chassis, resting a massive hand on its helm. "No one is hunting you. This thing has been dead for vorns. Mechs haven't been seen in the ocean for longer than I have been alive."
Orion froze, his panic faltering just a fraction. "They... they haven't?"
"No," Megatronus growled bitterly, sweeping his hand over the millions of glowing pearls. "And because they are gone, my eggs are dying. They will never hatch."
Orion stared at the glowing pearls, the difference in the other mermaid's biology was completely jarring. But before he could ask, Megatronus was looking at him. Really looking at him.
The confusion in the mermaid's crimson optics began to melt away, replaced by a dark, hungry calculation. He drifted closer, his slick body moving with terrifying, silent grace. Before Orion could dart away, Megatronus towered over him, his massive bulk completely blocking the exit and trapping Orion against the cavern wall.
"You don't swim right," Megatronus murmured, leaning down. "You have sparkling scales, can do miracles, and you said you need to go to the surface?"
"Megatronus..." Orion whispered, a new, suffocating fear gripping his spark.
Megatronus leaned in, his sharp dentae flashing in the dim light. A heavy, slick servo pinned Orion’s shoulder to the rock. With terrifying deliberation, Megatronus dragged his glossa over the delicate edge of Orion’s fin, tasting the energon signature pulsing just beneath the plating.
The not-so-mermaid pulled back. His optics burned a blinding, predatory red.
"You look like a siren," Megatronus rumbled, his voice dropping into a desperate, guttural purr. "But you taste like a mech."
The sheer biological need in Megatronus' voice was the only warning Orion got.
“You are not my people!” Orion shrieked.
Megatronus lunged, his frame slamming forward to crush Orion against the stone. But panic flared immediately. Orion’s servos erupted, sending a blinding, concussive shockwave straight into the siren's chest.
The blast didn't wound him, but it knocked the massive frame off balance just enough.
With a frantic, desperate twist of his agile body, Orion slipped right through Megatronus’s crushing grip. He shot upward, darting out of the kelp curtain and throwing himself blindly into the pitch-black abyss.
Behind him, a furious, deafening roar tore through the water.
Megatronus was after him.
Orion shot through the black water like a bolt of lightning, his spark hammering against his chassis.
The mermaid twisted and weaved desperately between the towering stalks, his cyan magic flaring in short, frantic bursts to light his path and throw off his pursuer. Every sweep of his tail burned, but fear gave him speed he didn’t know he possessed. The pressure of the deep pressed in from all sides, cold and crushing, but he couldn’t stop. Not now.
A massive shadow surged past him on the left, displacing enough water to send Orion tumbling. He corrected with a sharp twist, only for Megatronus to appear again, this time from above, his powerful tail cutting through the dark like a blade.
The siren’s crimson optics burned through the gloom, locked onto him with terrifying focus.
“You cannot outrun me, little fish!” Megatronus bellowed, voice booming through the water. “Not in my depths!”
Orion darted downward into a narrow trench, scraping his plating against jagged rock. Megatronus was too large to follow directly, but the siren simply smashed through the obstacle with brutal strength, sending debris and shattered stone exploding behind him.
The siren's getting closer. And Megatronus nearly caught him, twice.
A massive servos grazing Orion’s tail fin, claws scraping across his back plating. Each near-miss sent terrified jolts through Orion’s frame. The larger mech was relentless, a force of nature that was completely different from the spiritual mermaids. A unit that meant to hunt. To subdue.
As the glowing kelp began to thin. An open water loomed ahead, offering no shelter for the little mermaid to hide.
Megatronus exploded out of the kelp behind him with terrifying speed. Orion tried to dive again, but a servo clamped around his waist, yanking him backward with crushing force.
Before he could summon another magic spell, Megatronus’s powerful tail coiled around his own in a brutal, unyielding tangle, locking their lower bodies together and rendering Orion’s frantic tail strokes useless.
“No—!” Orion gasped, thrashing wildly.
A sharp, barbed stinger spine emerged from the underside of Megatronus’s tail, jabbing into the plating around Orion's tail. Hot venom flooded the puncture. It was a potent one since the siren's toxin was meant to weaken and arouse their prey.
Orion’s optics widened as the sensation spread through his circuits. The venom burned sweetly, forcing his interface panel to click open. His spike pressurized hard and fast against his will, springing out throbbing and flushed.
“Ahhah!!! What are you going to do with me!” The mermaid wails.
Megatronus let out a deep, broken purr, the sound vibrating through both their frames as he rubbed his heavy chassis desperately against Orion’s back.
Sharp dentae sank into the sensitive edge of the mermaid’s fin, biting down just hard enough to send sparks of pain and unwanted heat racing through his circuits. The bite pinned his helm in place as Megatronus pulled him flush against his massive chassis.
The siren was shaking. It wasn't gentle, and it wasn’t mean to be kind. This was the sound of centuries of lust finally getting fulfilled.
Megatronus rubbed his plating harder against Orion’s, grinding slowly, hungrily, as if he couldn’t stop touching even while holding him captive. Every inch of contact seemed to feed something desperate inside the huge siren.
“Finally…” Megatronus growled against his fin. His free servo roamed greedily, claws scraping lightly down Orion’s sides, tracing seams and pressing into sensitive plating. “Finally what I needed!… Oh... my clutch… they will thrive now!”
Orion whimpered, frame jerking inside the iron hold. Despite the fear, his spike still pressurized against his will as Megatronus’s servo slid lower, fingering Orion's valve with rough, demanding strokes.
Megatronus let out another deep, broken purr, rubbing his face against the bite mark he’d left. His abdominal pocket shifted, and a thick, slick ovipositor slowly emerged, already dripping with pearly eggs. Then, his servo wrapped firmly around Orion’s newly exposed spike, stroking it with slow, possessive hunger. He angled the flushed, leaking head and pressed it flush against the slick, twitching entrance of his own massive length of ovipositor, forcing them together in messy, obscene kisses.
The sensitive tip of Orion’s spike rubbed directly against the hot, pulsing opening. Smearing his own leaking transfluid across it in sticky strands of ooze far thicker than sea water itself.
“Megatronus, please… Don't do this…” Orion whimpered as the sensation was way too overwhelming.
And every slow stroke made his spikehead kiss deeper, it was the slick heat of Megatronus’s ovipositor entrance sucking and fluttering against his own spike’s entrance.
That was when the first 'pearl' began to move.
Orion could feel it. The thick, rounded bulge travels slowly up from the shaft of Megatronus’ ovipositor.
The firm little lump on Megatronus’ ovipositor nudged insistently against the underside of Orion's spike, pressing and sliding along the sensitive line before it climbed up reaching the tip. When the egg finally pushed out, it kissed directly against Orion’s spikehead, round and smooth and glistening as his spikehead immediately coated the egg in his leaking transfluid.
Megatronus stroked him harder, milked him out of his transfluid. And it didn't stop here. Not long after, another egg followed.
Then another.
And another.
Each one sent a visceral shiver through Orion. He could feel each egg traveling through the thick ovipositor, the way they stretched the entrance before nudging firmly against his spike , forcing the head of his spike to rub and kiss each emerging egg in turn.
It was too much.
Orion’s moans grew louder, helpless, his frame shuddering violently in the tight tail entanglement. The constant biting on his fin, the heavy rubbing of Megatronus’s chassis against his back, and the relentless egg-by-egg stimulation pushed him past his limit.
His spike throbbed violently in Megatronus’s grip, and with a sharp, desperate cry, Orion overloaded, cumming a thick, cloud of transfluid directly onto the freshly laid clutch, thoroughly inseminating the eggs in a shimmering, cloudy haze.
For one breathless moment, Megatronus purred in pure, possessive triumph. Before suddenly Orion’s servos flared with desperate cyan light.
The last act of his defience.
A violent surge of water exploded outward. The powerful current blast slammed into Megatronus’s chassis, breaking the tail entanglement and sending the freshly fertilized eggs scattering in every direction.
Dozens of glowing pearls drifting helplessly into the dark abyss. Some were immediately snatched up by opportunistic scavengers lurking in the trenches and other were crushed by the strong water. Megatronus roared in fury, the sound so deep and deafening as it shook the surrounding water like thunder. The ancient siren’s optics blazed with rage and heartbreak as he watched hundreds of his hopes vanish into the voids.
“You—!” he snarled, voice raw with betrayal.
Orion didn’t wait. The moment the entanglement loosened, he twisted free with a frantic burst of speed, shooting upward toward the crushing pressure of the shallow water. Spark hammered wildly in his chassis, every circuit screaming with exhaustion and fear.
Behind him, Megatronus gave chase once more. He smashed through kelp and rock alike, roaring Orion’s name like a curse and a prayer, the sound chasing him through the freezing water. The abyss seemed endless. But far above, a faint shimmer of lighter water beckoned.
Orion pushed harder, and the water grew lighter, but no less treacherous.
Frozen corals and towering icebergs created a deadly maze in the shallows. Orion weaved desperately between them, his exhausted frame scraping against jagged ice more than once. Behind him, Megatronus followed relentlessly.
“ORION!!!”
Orion ignored him, spark burning with hope when he spotted a faint glow above. With the last reserves of his strength, he surged upward and leaped through the opening.
It was a small hole in the thin ice layer covering the world.
Cold air slammed into his gills like a physical blow. He crashed onto the hard ice with a painful thud, coughing violently as his body struggled with the sudden change. For a moment, he simply lay there, vents heaving and optics wide with disbelief.
He had made it.
But the danger hadn’t stopped yet.
A heavy splash erupted after him. Megatronus broke the surface as well, only to let out a strangled roar of agony. The pressure difference crushed down on the abyss-born siren. Energon wept from his optics and sensors as his massive frame slammed onto the ice, cracking it beneath his weight. He thrashed once, twice, before desperately flopping back into the water through the same hole.
But he did not leave. That wasn’t enough to deter him away.
From just below the surface tension, Megatronus’s glowing crimson optics watched him, pleading and furious at him at the same time.
“Little fish… This isn’t a safe place for you to wander around. Come along, return to the water with me, I shall provide you better.”
But Orion didn’t reply. He lay on the cold ice for a long moment, vents still heaving as he tried to adjust to the thin, biting air. Slowly, he pushed himself up on trembling arms, fins flaring weakly against the frozen surface.
The world around him was a vast, desolate wasteland of ice. A thin crystalline layer stretched endlessly in every direction, broken only by jagged icebergs and frozen formations.
In the distance, something caught his optics. A familiar spire protruded from the ice, partially visible. Orion’s spark clenched with painful recognition.
He dragged himself closer, optics wide with dawning horror.
It was the roof of the Great Archive tower. Apparently, the entire city… had risen. What was once a thriving underwater kingdom was now entombed in ice, transformed into a frozen continent.
How long had he been lost in the abyss? Cycles? Vorns? His immortal frame had endured, but time had not waited for him.
“No…” he whispered hoarsely, voice cracking in the freezing wind. He called out louder, voice echoing across the empty ice.
“Alpha Trion…??!”
“Ratchet…??!!”
“Elita…?!!!”
“Jazz…!!!”
No answer came. Only the howling wind replied.
His family, his friends, his entire people — gone. Whether they had fled, been hunted, or simply faded with time, he might never know.
Now, he was all alone in a dead world. He stood on the frozen ice for what felt like an eternity, the cold seeping deep into his plating. His calls had faded into the wind, unanswered. The weight of loss pressed down on him heavier than the abyss ever had. Exhaustion, grief, and the lingering burn of venom made his frame tremble.
Slowly, almost against his will, he dragged himself back toward the small hole in the ice where he had emerged. He stopped at the edge, staring down into the dark water. Megatronus was still there, just below the surface, staring back at him with unsettling patience.
Then, a low, haunting melody began to rise from the depths.
The siren’s song.
It was sorrowful and alluring, wrapping around Orion’s spark like gentle currents. The notes carried centuries of loneliness, of waiting, and hopes. They tugged at his grief, his exhaustion, and the strange pull he felt toward the siren despite everything that had happened.
But, Orion didn’t dive back in.
He simply lowered himself onto the ice beside the hole, curling his tail close to his body. The cold bit into him, but he barely felt it anymore and the song continued, soft and lulling, promising rest and peace.
Then his optics grew heavier and the world tilted gently.
With a quiet sigh, Orion let the siren’s song wash over him completely. He slowly lowered his helm onto the frozen surface and fell into a deep, dreamless sleep.
As the time moved forward, the shocking reality of his past life had faded, and Orion eventually surrendered to the rhythm of his new existence.
Orion lay half-dozing in the soft kelp nest, curled comfortably on his side. The heavy fullness in his forge chamber was familiar now.
After successfully carrying and hatching three previous clutches, he had come to accept this new life with quiet, warm resignation. After all, Megatronus was here. He was no longer alone in this frozen, empty world. And strangely… he had begun to look forward to these moments.
Megatronus spooned him from behind, one thick arm wrapped protectively around his waist, servo rubbing slow, soothing circles over the swollen curve of his belly. The deep, steady purring against his back made Orion’s spark flutter with affection.
“They’re coming again,” The mermaid whispered, voice husky with anticipation. “Our fourth clutch…”
Megatronus nuzzled the back of his helm, dentae grazing lightly. “That’s my good mate. Let them out. I’m right here with you.”
Orion reached down between his thighs, slipping his valve open with practiced ease. The first fry wriggled down from his chamber, nudging and stretching the tight ring of his valve before pushing out with a rush of fluid. Each subsequent one rubbed and wiggled against his external node, sending sparks of pleasure through him.
With a low moan, Orion pressed back against Megatronus, silently asking for more help. The siren understood immediately, gently pressing down on Orion’s swollen belly. The added pressure quickened the release and more fry slipped free in a steady stream, each one writhing and escaping his valve in a rush of overwhelming pleasure.
Orion overloaded with a soft, blissful cry, valve clenching as the last of the fry escaped. His transfluid mixed with the release, helping the newborn fry dart excitedly into the water and hide among the prepared kelp nest.
After the last fry had safely hidden in the kelp nest, Orion turned his helm just enough to seek Megatronus’s mouth. The deep, loving kiss that followed made his spark glow with quiet happiness.
“We need to refill the chamber,” Megatronus murmured against his lips, voice low and hungry.
“Yes…” Orion breathed, pressing back against him. “Please.”
Their glossa comeback to tangled slowly, sensually. Orion’s servo slid down between their bodies, wrapping around the thick base of Megatronus’ emerging ovipositor and stroking it with long, affectionate motions. As the kiss grew heated, breathless. Megatronus pulled back just enough to murmur against Orion’s lips.
“Shift for me, love.”
Orion obeyed, adjusting his body on his side.
The siren aligned the thick head of his long ovipositor against the slick entrance, he didn't hesitate on tangling their tails together tightly, locking them in place to keep Orion steady.
Megatronus pinned them together against the soft kelp nest under them before he began to thrust.
The long, thick ovipositor pushed slowly into Orion’s still-sensitive valve, stretching him open with a delicious moan. Orion trembled at the sheer length trying to breach deeper into his forge chamber. Even though Megatronus couldn’t bury the entire impressive length, the portion that entered was already overwhelming.
The siren’s thrusts gradually became faster and deeper. The bubbling, rhythmic sounds of their joining filling the den. Orion’s moans also grew louder, valve clenching desperately around the invading shaft.
“Megatronus—!” The mermaid cried out as pleasure spiked sharply. His overload hit hard, valve pulsing and sucking greedily at the tip of the ovipositor.
With a low snarl, Megatronus gave one sharp, powerful thrust. The head of his ovipositor finally breached the small opening of Orion’s forge chamber and Orion trembled hard in Megatronus’s hold, vents cycling rapidly as he tried to adjust to the overwhelming fullness. Megatronus stayed still for a moment, buried as deep as the long ovipositor would allow, simply holding him close and purring softly against his fin to soothe him.
“Nyeh— M–Megatron—!!!”
Then the first egg began to move.
Orion felt the rounded bulge traveling down the shaft of Megatronus’s ovipositor. It pressed against the stretched entrance of his valve, nudging insistently against his swollen node before slowly pushing inside.
Orion shivered violently, his valve beginning to pulse rhythmically around the thick intrusion and Megatronus growled low in pleasure at the tight, welcoming squeeze. The sensation of the valve clenching around his ovipositor seemed to stimulate Megatronus’s tank.
The siren growled deeply, hips snapping forward as more eggs began to follow in quick succession.
Orion overloaded again and again, each powerful wave making his valve clench and flutter greedily around the thick shaft. His moans were muffled against Megatronus’s mouth as they kissed desperately between breaths.
Megatronus kept one servo firmly wrapped around Orion’s spike, stroking it through every overload, while using his thumb to carefully seal the tip, forcing every pulse of transfluid to travel back into Orion’s valve instead of escaping into the water.
Orion overloaded hard. The feeling of his own warm transfluid being pushed back deep inside alongside the eggs made Orion shudder with overwhelming pleasure.
A long while afterward, both panting softly. Megatronus released his servos from Orion and wrapped his arms around his chassis instead, holding him close in a protective embrace. He pressed gentle, lingering kisses to Orion’s fin, his bite mark, and finally his lips.
“Such compliant,” Megatronus murmured between kisses, voice warm with affection. “My beautiful little fish.”
Orion smiled tiredly, nuzzling back into the kiss. After a moment of comfortable silence, he spoke softly.
“Megatronus… next time we go hunting near the surface ruins, can I bring back that jeweled crest I found in the remains of the Archive? It’s so pretty.”
Megatronus let out a low, disapproval rumble. “Another useless trinket!? You keep bringing those shiny scraps into our den. They have no value for us..”
Orion pouted playfully, still nestled against his chest. “Mermaids treasure beautiful things the same way sirens treasure their dens. It’s important to us.”
Megatronus huffed, clearly suspecting Orion was making the whole tradition up on the spot, but his optics softened with fondness. He kissed Orion again, slow and sweet.
“…Very well. We’ll bring your shiny rock back to our home. And maybe we should make the den bigger if you’re going to keep hoarding them.”
Orion’s spark glowed with quiet happiness as he curled closer, content in his mate’s arms.