The night was moonless.
The sky hung low over the grounds of Hogwarts, heavy with clouds, shrouding the castle in a muffled quiet. It was just past midnight when Percy, Harry, Hermione, and Ron slipped out of the common room, beneath the cover of an invisibility cloak borrowed. Well, technically stolen again, from Harry's trunk.
They moved like shadows down the sloping path to the Black Lake. Their boots were silent in the wet grass, their breaths quick with anticipation and fear. Percy felt it pulsing beneath his ribs: the magic. Not nervousness, not adrenaline, but that strange, electric force that seemed to know something was coming.
The shoreline was deserted. The lake, black as ink, rippled softly.
"Alright," Harry said, pulling off the cloak. "We're clear."
Percy stepped forward, wand already drawn. "Everyone ready?"
Ron swallowed audibly. "Define ready."
"Not about to turn back," Hermione translated, her voice brisk but tight.
Percy nodded. "Stay close to me once we're in the water. The Glacien Vade spell is meant to extend to others… I think. Just don't drift too far."
He closed his eyes. Focused.
The magic came easier now.
"Glacien Vade."
There was no flash of light. Instead, a hum began in Percy's bones and spread outward. The air around them shimmered like heat off stone, and the water ahead grew still. Then, one by one, they stepped forward, and the lake parted.
Not completely, there was no dramatic tunnel, but water peeled back in a dome around them, pressing away in a flickering, translucent barrier. They could breathe. They could see. The world below the surface unfolded in green and silver hues.
Hermione's eyes were wide with wonder. "It's like… we're walking through a dream."
"More like a nightmare," Ron muttered, eyeing a school of glowing, sharp-finned fish that darted past.
They moved slowly, carefully, along the lakebed. Rocks and old chains from the boats lay scattered among waving weeds. A grindylow skittered out of sight behind a rock. Above them, the surface glistened like a mirror ceiling, bending the light of Hogwarts behind them.
Then the ground dropped away.
Percy stopped at the edge of a steep descent into a trench, a fissure in the earth that seemed to go on forever. And there, embedded in the rocky wall of the ravine, was a door.
Not just any door.
It shimmered like silver glass, ancient runes glowing faintly across its surface. Carvings of sea creatures curled around the edges: serpents, dolphins, hippocampi, all entwined with symbols Percy didn't recognize, but somehow understood.
"This is it," he whispered.
Hermione pulled out a waterproofed scroll from her satchel. "These runes, some are Atlantean. I think… this part says, "He who bears the mark may enter."
"Mark?" Harry asked.
Percy didn't answer. He reached out.
The moment his fingers touched the surface of the door, the runes blazed to life. The magic in his chest surged outward like a heartbeat, resonating with the door.
With a soft grinding noise, it swung inward.
Revealing darkness.
Beyond the threshold was a tunnel, carved from the same silvery stone, sloping downward into the deep. Lightless. Breathless. Waiting.
Ron hesitated. "This is a terrible idea."
"Yeah," Percy agreed. "But we've come this far."
They stepped through.
The air changed immediately. Colder. Stiller. The walls of the tunnel pulsed faintly, like veins carrying a memory of magic. The further they walked, the more Percy felt the pull, like gravity, but inside his soul.
Then they entered the first chamber.
It was vast. A domed hall with no visible ceiling, only darkness above. Columns of coral and pearl rose on every side. In the center of the floor lay a basin, shallow and wide, filled with swirling black liquid that reflected none of the light from their wands.
Hermione bent beside it. "This… isn't water."
Percy stepped closer, and the basin stirred.
A voice, ancient, feminine, and echoing from everywhere and nowhere, rose from the depths:
"Heir of sea and sky… the tide returns."
The room trembled.
Symbols flared on the walls. The basin's black liquid began to rise, shaping itself into something alive.
A figure emerged. Human in form, but made of shimmering ink and water. Its eyes opened, pure white, glowing. It looked directly at Percy.
And smiled.
"You are not ready," it said. "But you are chosen."
The floor cracked beneath their feet. Water exploded upward.
And everything went black.
Percy woke to silence.
It wasn't the kind of silence one found in the Hogwarts Library or late at night in the common room. This was a deep, absolute quiet, so thick it felt like sound itself had been banished. His head throbbed with dull pressure. The air was dense, humid, and tinged with salt.
He blinked slowly. The light above him shimmered through rippling water, casting moving shadows over the ceiling of smooth stone.
Where was he?
He sat up.
He wasn't underwater, not anymore. At least, not directly. He was lying on a flat stone platform, surrounded by shallow pools that reflected the strange, bluish glow of the room. The walls were curved, like a shell, and lined with faintly glowing symbols. The magic here was old. Older than Hogwarts, older than even the Founders. It pulsed beneath his skin like a second heartbeat.
To his right, Hermione stirred.
She groaned softly, rubbing her temples. "Wha… what happened?"
"I don't know," Percy said, standing. His clothes were damp but breathable, the spell still clinging to his skin. "We must've been knocked unconscious. That… thing in the basin. It triggered something."
Hermione pushed herself upright, eyes scanning the room in a mix of wonder and wariness. "Where are Ron and Harry?"
Percy turned slowly, eyes darting. The room was large, shaped like a half-dome, and carved into a single piece of rock. Two stone archways led out in opposite directions. No Ron. No Harry.
"They were right next to us," he muttered. "They couldn't have gone far."
As if on cue, a faint, echoing clang rang out from the left archway, metal hitting stone.
Hermione leapt to her feet. "That could be them."
Together, they hurried through the passage.
The corridor narrowed and sloped slightly downward. The floor had a thin film of water across it, no deeper than an inch, which rippled with every step. Strange markings lined the walls, and once or twice Percy swore he saw one of them shift when he passed.
At last, the corridor opened into a round chamber, different from the first.
Here, a stone altar sat in the center, and around it, large statues of sea creatures, krakens, hippocampi, leviathans, stood in silent watch. And there, leaning against the altar and groaning, was Ron.
"Ron!" Hermione cried, rushing to his side.
He blinked up blearily. "Oh, good, it's you. I was afraid I'd be stuck in a cave full of squid monsters."
Percy looked around. "Where's Harry?"
Ron frowned. "He was here when I woke up. Then… I heard a voice. He went through that passage—" He pointed to a darker hallway on the far side. "He said he thought someone was calling him."
Percy's stomach turned.
Hermione bit her lip. "Do you think—?"
"Yes," Percy said grimly. "This place isn't just ruins. It's alive. And it wants something from us."
Before anyone could respond, the ground beneath their feet rumbled. A low vibration traveled through the stone—something was moving, something large. And close.
Then they heard Harry.
Not his voice, but a scream.
Cut off.
The three of them bolted down the hall where Ron had last seen him. The air grew colder as they ran, and the markings on the wall glowed brighter with every step.
After what felt like a mile, they burst into another chamber.
It was a shrine. Massive, circular, and hollow. In its center, floating above a pedestal of obsidian, was Harry.
Suspended.
Wrapped in tendrils of shadowy water, twisting around his limbs like vines. His eyes were closed. Around the pedestal, four massive carvings loomed. One for each of the cardinal seas: Atlantic, Pacific, Arctic, Indian. The magic was ancient, and angry.
"Harry!" Hermione shouted.
Percy stepped forward, wand raised, but a blast of water surged out and threw him back. He slammed into the wall, breath knocked from his lungs.
"Percy!" Ron rushed to help, but Percy waved him off, coughing.
"No," Percy gasped, eyes fixed on the pulsing shrine. "This is it. This is what it's guarding. Or… protecting."
Hermione's eyes widened as the runes overhead shifted and aligned, glowing in patterns that matched the markings on Percy's forearm.
"The shrine is reacting to you," she whispered. "Percy, I think you're the only one who can stop it."
Percy staggered forward, raising his hand toward the pedestal. The markings on his skin burned bright.
The chamber lit up.
Magic flared.
The tendrils of water shrieked as if in pain, and then everything went white.
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Interlude~
Hi guys, just forcing this into the middle of the chapter to tell you that i'm back! I just finished some exams and took a break from writing for a short while. But now, I'm back! Yeah! YEAA! YEAAAAAAAA-
Anyways, I will try to update weekly again but that may be a little hard, so expect a absolutely inconsistent update schedule OWO. Also, the next part was originally supposed to be another chapter but I wanted to give y'all more story :P
Welp, back to the story!
End of interlude~
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Harry Potter had faced many strange things in his life. Voldemort's shade in the Forbidden Forest, a basilisk beneath the school, even time travel. But nothing prepared him for the cold embrace of this shrine.
The moment he stepped into the final chamber, something ancient had called to him. Not with words, but with memory. It had wrapped around his mind like fog, pulling him into the darkness before he could shout for the others. Now, he floated, trapped in a vast space where time didn't flow.
The world around him shimmered in deep blues and black shadows, the edges of the room dissolving into endless water. No air, yet he could breathe. No floor, yet he wasn't falling. He was suspended in the center of a mind. Not his own, but something old. Something watching.
Then… the visions began.
A cracking sky, rent (A/N: Rended?)open by lightning that struck not from the heavens, but from the seas below. Ships shattered like toys on a bathtub. He saw towering waves with faces. Faces twisted in rage and sorrow. A city underwater, gold-domed and silent, its people frozen in time like statues of coral and pearl.
Then came the voice.
"You are not the one. Yet you are marked by prophecy."
Harry turned instinctively, but there was no direction here.
"You have walked paths of death and shadow. But others walk alongside you. Sons of old gods and hidden heirs."
The waters rippled with energy. Something moved in the darkness beyond. Immense and slow, the curve of a serpentine body larger than any dragon. The pressure in Harry's skull grew.
"He must choose. The heir of Poseidon. He must awaken what sleeps."
"You cannot stop what is rising. Only delay it."
Then, faster, the visions shifted again.
Percy, standing before the same shrine but older, cloaked in shadows, the trident on his wrist glowing like fire. He was surrounded by enemies. Wizards in dark robes, and monstrous creatures from the depths. Harry saw himself too, at Percy's side. Older, hardened. Changed.
"You are bound together. Fire and water. The Boy Who Lived. The Son of the Sea."
Harry's heart raced.
"What does it mean?" he tried to shout, but no sound came. Only a rush of bubbles. The light overhead dimmed. The pressure built again.
Suddenly, the dark water twisted around him like chains. His scar burned. Not dully like it used to, but with something new. Not like when Voldemort was close.
This was older than Voldemort.
He was being tested.
"If he fails... if he turns away from who he is… the ocean will reclaim the land. And magic itself will drown."
The words sank into him like ice.
Then—
A blinding light tore through the chamber.
The chains shattered.
Harry gasped, real air! His limbs dropped free and he fell forward, landing hard on a stone floor. He coughed and blinked, the cold seeping out of his bones.
"Harry!" Percy's voice. Real. Panicked.
He turned.
Percy stood a few feet away, wand out, glowing with sea-green magic. Behind him, Ron and Hermione looked pale and terrified, but alive.
"You—" Harry tried to speak, but his throat was raw. "You opened it."
Percy nodded. "Whatever it was, it was waiting for us."
Harry slowly got to his feet. "It showed me something. About you. About what's coming."
Percy's expression darkened. "You saw it too, then."
"What is it?" Hermione whispered. "What's rising?"
Before anyone could answer, the shrine behind them groaned, not just from shifting stone, but from a living sound, a call echoing far beyond this room. Something ancient had been stirred.
Not awakened… yet.
But it was close.
Very close.
To Be Continued ~~~
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Where will our intrepid explorers go next? find out in the next epis- I mean chapter of Pjo x HP!