100 Prompt Challenge - Astelle

Prompt: Request from S4cy, a loosely based Little Mermaid AU. (Loosely based because I don't know shit about Little Mermaid, I'm writing this based off some tik toks, reels, AI Notes/recommendations, and Wikipedia)

—

Beneath the shimmering waves of the Azure Deep, hidden beyond the jagged reefs and the vast trenches, lay the Seabed Temple—a kingdom of coral spires and bioluminescent gardens, ruled by King Nozel Silva. The temple's people, proud and wary, harbored a deep hatred for the land-dwellers who, they believed, had taken their beloved former ruler, Queen Acier.

Among them was Princess Noelle Silva, a mermaid of unmatched grace and power. Her flowing silver hair trailed behind her like moonlight on water, and her armored fins gleamed with a radiance befitting her royal bloodline. Yet despite her lineage, she was never seen as her mother's equal—always too weak, too uncertain, too different.

Most of all, she was curious about the surface.

"Noelle, you are forbidden from going near the sky," Nozel's voice was as sharp as the trident he carried. "You know what happened to our mother."

"But—"

"No 'but's. A future queen must think of her people, not chase after foolish dreams."

Noelle clenched her fists, her heart heavy with longing. She had never even seen a human before, only heard the warnings. "They are cruel," Nozel had told her. "They are conquerors, who take what they want and leave ruin behind."

Yet, something inside her ached to see the world above.

And so, she did what any rebellious princess would do.

That night, under the veil of a rising moon, she slipped past the guards and swam upward, past the kelp forests, past the jagged ridges that marked the boundary of the Seabed Temple's domain, and toward the surface.

As she broke through the waves, the air felt strange—thin and weightless compared to the heavy embrace of the ocean. But the sky—the sky!—was endless. Black as ink, yet littered with diamond-like stars that seemed to pulse in time with her racing heart.

And then she saw him.

A ship loomed above, its dark sails carrying the crest of the Spade Kingdom—the world's most powerful empire, the one that had conquered every land, every sea. Standing at the helm, laughing without restraint, was a boy.

He had hair as wild as the wind and green eyes as bright as the sun. He was shorter than the others but stood taller than any of them in presence alone.

Noelle didn't know why, but she couldn't look away.

—

Asta felt the eyes before he saw them.

He had been standing at the edge of the deck, letting the salty wind rush past him, when he noticed the glimmer of silver beneath the waves. At first, he thought it was a trick of the moonlight, but then he saw her.

A girl with the most beautiful eyes he had ever seen.

He blinked. Was he imagining this? A mermaid?

"Oi, Prince Asta! You're spacing out again," called Finral, his trusted navigator. "Don't tell me you believe in those mermaid stories?"

Asta grinned, leaning on the railing. "And what if I do?"

"Hah! Then you'd be the first Spade Prince to believe in fairytales."

Asta ignored him. He had grown up in the Spade royal palace, an orphan raised by the ruthless King Dante, but unlike his so-called family, he had never cared for bloodlines or power. He wanted freedom—freedom from expectations, from politics, from wars.

And right now, that freedom looked a lot like a pair of curious, violet eyes watching him from the sea.

He took a step forward, about to speak—

When a massive storm struck.

—

The ship lurched violently. Noelle gasped as waves crashed against the hull, threatening to tear it apart. She didn't understand—there had been no signs of a storm moments ago!

Lightning split the sky.

Sailors shouted in panic.

And then—Asta fell.

Noelle's heart stopped as she saw him plunge into the water. The other humans didn't even see it happen in the chaos. He was sinking fast.

Without thinking, she dived after him.

The moment her arms wrapped around his unconscious body, she felt an unfamiliar warmth against her skin. He was so warm. It was strange. It was intoxicating.

And it was dangerous.

She carried him to shore, laying him gently on the wet sand. For the first time, she truly saw him up close.

His features were sharp but kind, his body strong yet unguarded in sleep. He wasn't like she imagined a human would be. He wasn't cruel, wasn't some terrifying monster.

He was just… a boy.

A boy she wanted to know more about.

The sun was beginning to rise. She knew she had to leave before anyone saw her, but before she could retreat, his eyes fluttered open.

"…Wha—?" Asta groaned, blinking against the sunlight. And then his gaze locked onto hers.

Noelle froze.

A moment stretched between them—endless, weightless.

"Who… are you?" Asta whispered, voice hoarse.

Panic seized her. She couldn't let him know, couldn't risk everything she had. She turned, diving back into the waves, her heart hammering in her chest.

She didn't hear Asta sit up, didn't see the awed smile spread across his face.

But she did hear his voice—soft, breathless, wondering.

"I'll find you."

—

Deep in the shadows of the Seabed Temple, a sinister smile curled on Vanica's lips.

"So the little princess has finally tasted forbidden love."

The rogue Dark Mage of the Deep, the woman who had once stood by Acier's side before betraying her, watched with cruel amusement. Noelle was just like her mother—foolish, trusting.

But unlike Acier, Noelle was still useful.

"If she wants to be with him so badly…" Vanica murmured, trailing a finger along the cursed runes on her arm, "then let's see how far she'll go."

And with a whispered spell, the ocean trembled.

—

Noelle couldn't stop thinking about him.

Even days after the storm, she found herself lingering near the surface, hidden behind rocks, watching the human ships come and go. She knew it was reckless. She knew it was dangerous. But she couldn't forget his voice, the way he had looked at her—not with fear, not with disgust, but with wonder.

Somewhere deep in her heart, she longed to see that look again.

And then, one night, Vanica found her.

—

The rogue dark mage lounged atop a coral throne, one leg thrown over the other as she twirled a strand of her dark hair. Around them, the waters were thick with curses, twisting and writhing like living things. Noelle had never ventured this far into the abyss before, and everything inside her screamed that she should run.

But she didn't.

Because Vanica had whispered something to her—something impossible.

"You want to be with that human, don't you?" Vanica's grin was sharp as a blade. "I can help with that."

Noelle's heart pounded. "You—how do you know about—"

Vanica laughed. "Please. You think your little escapades go unnoticed? I've been watching you for a long time, princess. You're just like your mother." Her expression darkened. "Naïve. But lucky for you, I'm feeling generous today."

Noelle gritted her teeth. "Why would you help me?"

Vanica leaned in, resting her chin on her hand. "Let's just say I have my own reasons for wanting you out of the way."

Noelle stiffened. This was wrong. Every part of her told her not to trust this woman. And yet—

Asta's voice echoed in her mind. Who are you?

Vanica smirked, seeing the hesitation in Noelle's eyes. "I can make you human," she said, voice dripping with temptation. "You'll be able to walk on land, be with your prince, live out your little fairy tale dream."

Noelle's breath caught.

Human.

She could stand by his side. She wouldn't have to hide.

But at what cost?

"…What's the price?" she asked warily.

Vanica grinned. "Smart girl. But don't worry, I'm not asking for much. Just a little…" She reached out, tapping a finger to Noelle's throat.

"…Silence."

Noelle's blood ran cold.

"If you accept my deal," Vanica continued, "you'll lose your voice. You won't be able to speak, to tell him the truth, to explain who you are. And if—" her eyes glowed red with amusement, "—he doesn't fall in love with you by the next full moon, you'll return to the sea, and I'll take something even more precious."

Noelle swallowed hard.

"And what," she asked, barely above a whisper, "is that?"

Vanica grinned wider.

"Your soul."

—

Noelle knew it was reckless. Knew it was foolish.

But the moment she signed the deal with a drop of her blood, she felt the curse take hold. A searing pain shot through her throat, and she gasped, but no sound came out.

She tried again. Nothing.

Her voice was gone.

And then the transformation began.

Her fins shimmered, dissolving into legs, foreign and unsteady. The ocean itself seemed to reject her, pulling away as if she no longer belonged. A heavy force dragged her down, suffocating, crushing—

And then—

She broke through the surface.

The first breath of air burned her lungs.

The first step on the sand made her legs tremble, weak and unfamiliar.

And the first pair of hands that caught her before she could collapse belonged to Asta.

"Noelle?!"

Her eyes widened. He remembered her.

But before she could say anything—before she could even try—no voice came out.

Nothing but silence.

—

Asta was stunned.

The girl from the ocean—the same girl he had seen that night, the one who had vanished into the waves—was here, right in front of him.

And she was human.

But something was wrong.

She tried to speak, but no sound came out. Her face twisted in frustration, and Asta immediately understood.

"You… can't talk?" he asked gently.

She nodded, looking away.

Asta frowned, but he quickly shook it off and grinned. "That's okay! You're still amazing!"

Noelle's eyes widened slightly.

"You don't have to talk for me to know you're special," Asta continued. "I mean, you saved my life, didn't you?"

Her heart skipped a beat.

He knew.

"I never got to thank you for that," Asta said, rubbing the back of his head. "So… thank you."

Noelle looked away, heat creeping up her face.

Asta chuckled. "You're kinda cute when you do that."

Her blush deepened, and Asta laughed harder.

She punched him in the arm.

It only made him laugh more.

Noelle huffed. What an idiot.

But she couldn't stop the small, reluctant smile that tugged at her lips.

—

For days, Noelle stayed at Asta's castle in Spade, growing closer to him. He took her around the palace, showed her the gardens, the starlit balcony, the library—all things she had only ever dreamed of.

But her silence made things difficult. She couldn't explain who she was, couldn't tell him about Vanica's curse, couldn't warn him of the dangers lurking in the depths.

And worse—Asta's people were watching her.

Some of the Spade nobles sneered at her, whispering behind their hands.

"A commoner girl?"

"She's pretty, but mute? How unfortunate."

"She isn't even from a proper noble house. Where did she come from?"

Noelle knew how to handle insults—she had heard them all her life. But she hadn't expected Asta to snap the way he did.

"If I hear one more person insult her, I'll throw you out myself!" Asta had roared, shocking the entire court.

Noelle stared at him, wide-eyed.

He defended her.

And he didn't even know who she really was.

Her heart ached.

But time was running out.

The full moon was fast approaching, and Asta still hadn't realized the truth. He cared about her—maybe even liked her—but was it enough?

And in the shadows, Vanica watched, waiting for her moment to strike.

Her lips curled into a cruel smirk.

"Oh, Noelle," she whispered. "You have no idea what's coming next."

—

The full moon hung high in the sky.

Noelle's time was almost up.

She gripped the castle balcony railing, staring out at the endless ocean. The waves crashed below, a rhythmic reminder that she didn't belong here.

Not yet. Not until Asta chose her.

If he didn't love her fully, if he didn't kiss her before the moon reached its peak—

She would lose everything.

Her body. Her soul.

And worst of all—she would lose him.

—

Deep in the ocean, Nozel was furious.

Not because he had to leave his kingdom. Not even because he had to breathe surface air.

But because he had been deceived.

His mother had not been killed by humans.

Acier had died at the hands of a traitor—a so-called mermaid who had never belonged to their kind in the first place.

Vanica.

A human.

A human who had used forbidden magic to disguise herself, to live among them, to manipulate them.

A human who had tricked Nozel into hating his own sister for dreaming of the surface.

Rage surged through his veins.

He turned to his soldiers. "We end this tonight."

And they ascended toward the shore.

—

At the castle, a grand ball was being held.

Asta felt off.

Everything about tonight felt forced—like something was pushing him in a direction he didn't want to go.

Then, in the middle of the ball, the doors burst open.

And there she was.

Vanica.

Only—

She wasn't a mermaid.

As the moonlight hit her skin, the illusion shattered.

Scales melted into pale human flesh. The fins that had once made her appear like one of Noelle's kind burned away, revealing bare legs.

Gasps rang through the ballroom.

Asta's eyes widened. "You're—"

"A fraud?" Vanica grinned. "You could say that."

She laughed, stretching like she had just awoken from a long nap. "Honestly, it was a pain keeping that form up for so long. But Dante was right. It was worth it."

The mention of the name sent a chill down Noelle's spine.

She had heard that name before.

Dante. The King of Spade.

Asta's adoptive father.

She looked at Asta—saw the way his face darkened, the tension in his fists.

He knew something.

"…You were working with Dante?" Asta's voice was dangerously low.

Vanica grinned. "Of course. I only infiltrated the Seabed Temple for one reason—to remove the last person who could stop Spade from taking the oceans for ourselves."

Noelle's breath caught.

Her mother.

It had never been humans.

It had been them—Dante and Vanica.

"I should thank you, Noelle," Vanica said with a smirk. "By coming to the surface, you made this so much easier."

Before Noelle could react, a deep voice echoed through the ballroom.

"She's right."

The chandeliers shook. The very walls of the castle trembled.

And then—Dante appeared.

The King of Spade strolled into the hall like he owned it, his cold gaze sweeping over the gathered nobles. Black mist curled around him, shadows that seemed to shift and whisper.

Asta's jaw clenched.

"Father."

Dante smirked. "Asta. My greatest disappointment."

Noelle's pulse pounded. The truth had finally surfaced—dark, ugly, and worse than she ever imagined.

Everything Vanica had said.

Everything Dante had done.

They had stolen her mother from her. They had orchestrated everything.

Asta's fists clenched so tightly his knuckles went white.

Noelle could see it—the storm inside him, the betrayal, the anger.

Her own rage burned, drowning out her fear, her doubts, everything else.

She turned to Asta.

And kissed him.

The ballroom vanished. The gasps of the nobles, the shifting shadows, even the threat of Dante himself

—

It all fell away.

Asta's eyes widened for only a second before he pulled her closer, hands gripping her waist, returning the kiss like he'd been waiting for this moment his entire life.

Noelle's magic surged. Water rose around them, shimmering like moonlight.

Asta grinned against her lips as they pulled apart. "That was—"

"Shut up," Noelle said breathlessly. "And fight with me."

His grin widened. "Gladly."

Dante sighed. "Touching. But it won't save you."

His darkness surged—

And Asta lunged.

—

Curses and shadows lashed through the air.

Vanica and Dante moved in perfect sync—a human and a traitor, two forces of destruction—as they attacked from both sides.

But Asta and Noelle stood together.

Asta's sword burned with power, slicing through Vanica's curses with ease. Noelle's water surged, forming a dragon that coiled around her like armor.

And then—Nozel arrived.

The entire ballroom shook as he landed, trident in hand, his magic surging like a tidal wave.

"Dante," he said coldly, eyes burning with fury.

The Spade King smirked. "Ah. The little king of fish-people."

Nozel's trident glowed. "Your time is up."

The battle raged harder than ever.

Asta and Vanica clashed in a whirlwind of steel and magic, their blades screaming as they met again and again.

Noelle and Dante's power collided, water and darkness twisting into a chaotic storm.

And Nozel—his rage finally unleashed—drove his trident straight through the heart of Spade's ambition.

With one final strike, the tides turned.

Asta's sword cleaved through Vanica's chest—her scream cut short as her magic shattered.

Noelle's water drowned Dante's darkness, and with a last, desperate gasp, the King of Spade fell.

And then—

Silence.

The war between sea and land had ended.

—

The next morning, as the sun rose over the ocean, Nozel spoke before his people.

"We were deceived," he said. "Our greatest enemy was not the surface—but the one who walked among us in disguise."

His gaze swept over the crowd.

"But it is over. And from this day forward, we will no longer live in fear."

The mermaids murmured, hesitant.

Then, Noelle stepped forward.

She reached for Asta's hand—in front of everyone—and held it tight.

"It's time for a new beginning," she said firmly. "One where the ocean and the land stand together."

Asta grinned.

"We'll prove it to you."

Nozel studied them for a long, tense moment.

And then—he nodded.

A ripple of change spread through the crowd.

The war was over.

And as Asta pulled Noelle close, spinning her into his arms beneath the golden morning light, she knew—

This was just the beginning of their story.