Flashback – Beacon Training Grounds, Days Before Departure
The midday sun hung high above the training field, casting long shadows over the packed dirt. The air was still—until the ground trembled.
A deep, guttural growl rolled across the area as Onyx's Nuckelavee shifted where it stood, bone-white hooves grinding into the earth. Steam hissed from the equine half's nostrils as its imp rider twitched unnaturally atop the massive body.
Ruby, Weiss, Blake, Yang, Jaune, Pyrrha, Nora, and Ren stood a good distance away. Even knowing it was under Onyx's control did nothing to lessen the dread it radiated.
The Nuckelavee's amethyst eyes gleamed faintly, its presence oppressive and heavy.
Onyx stepped forward, resting a calm hand against its foreleg.
"Before we depart for Kuroyuki," he said evenly, as he pets it "you need to understand a Nuckelavee's strengths—and its weaknesses—if you're going to face one in the wild."
He turned to face them, his tone sharpening into the measured cadence of a strategist.
"This is one of the most dangerous Grimm to walk Remnant. You don't defeat it with brute force. You defeat it by understanding how it fights."
At his gesture, the Nuckelavee straightened, responding with eerie obedience.
"First—extendable arms."
The rider's sinewy limbs snapped outward, stretching far beyond natural limits. They cracked the air like whips, gouging shallow trenches into the dirt. Ruby and Jaune both flinched instinctively.
"It can strike from a distance, grab terrain, or attack multiple enemies at once," Onyx explained. "If you stop moving, you die."
"Second—piercing screech."
At a short signal from Onyx, the rider tilted its head back.
The scream tore through the training grounds—a metallic, bone-rattling shriek that made teeth ache and vision blur. Team RWBY and JNPR clutched their ears, grimacing.
"It disorients. It stuns. It instills fear," Onyx continued once silence returned, his voice cutting cleanly through the ringing in their ears. "Panic fractures coordination. Fear makes you hesitate. And hesitation is what it hunts. Never cluster together. Never stay close when it screams."
His gaze hardened.
"Third—strength and durability."
Shadows gathered in his hand as he formed a blade from his Semblance. He struck the Nuckelavee's plated leg. The blow rang out with a dull clang and slid harmlessly aside. He followed with a controlled slash across its hide—only a shallow cut forming.
"Its bone armor and hide can withstand slashes, Dust rounds, even grenades," Onyx explained. "It will absorb punishment and keep advancing. Its muscles and equine frame are immense—each strike can crush stone, hurl debris, and overwhelm a single Huntsman in seconds. Blunt force, piercing attacks, or if your Aura mastery is high enough, Aura-infused strikes are your best options at hurting it."
He dispelled the blade and turned his head slightly.
"And finally—intelligence."
The Nuckelavee mirrored his movement, its rider watching him intently, like a soldier awaiting orders.
"This is not a mindless Grimm," Onyx said. "It learns. It adapts. It plans. It remembers its prey. If you repeat tactics, it will counter them."
He faced the teams once more.
"To kill it, you sever the whole by destroying the horse first," Onyx said evenly. "Stop its movement. Then control its reach. Once the equine body and reach are neutralized, the rider is exposed."
He pointed to the ground.
"There are two reliable ways to do this."
With a subtle gesture, the rider's elongated arms speared into the dirt, burying themselves deep like living anchors.
"Either immobilize the legs—pits, collapsed terrain, anything that robs it of mobility…"
His hand shifted slightly.
"…or turn its own arms into restraints. Pin them. Anchor them. Force the horse to the ground. It cannot escape without ripping its arms."
The arms flexed, demonstrating the restraint with disturbing precision.
Nora cracked a grin despite the tension. "So… we break its legs."
Onyx's lips curved into a small, approving smile.
"Yes," he said. "You break its legs."
Yang smirked. "Brutal. I like it."
Jaune lowered his sword slightly, frowning. "Then why don't you just kill it yourself? You already beat one of these before." He nodded toward the restrained Grimm.
Onyx met his gaze, calm but unyielding.
"Because, like I told Glynda earlier, experience matters," he replied. "And this fight—" his eyes shifted to Ren and Nora "—doesn't belong to me."
Ren stood perfectly still, hands clenched at his sides.
Nora's eyes burned with quiet fury.
The Nuckelavee snorted, mist curling from its muzzle like smoke. Even restrained, its presence reopened old wounds neither of them had forgotten.
Onyx let the shadows fade from his hand, his voice softer—but no less firm.
"You'll face it soon. When you do, don't let fear control you. Use it."
He turned back to his Grimm and gave a faint nod.
Onyx's Nuckelavee dissolved into black smoke—
and from that same smoke, a massive Nuckelavee charged forward, the memory collapsing into reality as the scene snapped back to the—
Present – Kuroyuki Outskirts
Its massive hooves smashed into the cracked ground like falling boulders, sending tremors through the ruins. Dust, shattered stone, and twisted metal erupted with each strike. Its rider shrieked, a guttural wail that sliced through the fog, shaking even the distant trees.
Onyx braced, halberd spinning once before he stepped forward, placing himself between the beast and the others. Shadows curled around his boots like living serpents.
Ren and Nora flanked him, eyes burning with purpose.
"Here it comes!" Nora shouted, hammer raised, Dust flares igniting along the edges.
The Nuckelavee swung one grotesque arm, cracking the ground where the trio had just stood. They split apart—Onyx darting left, Ren rolling right, Nora vaulting a collapsing wall as debris rained around them.
The horse reared, hooves pounding down with bone-shattering force. Ren hit the dirt hard, his blades skittering away, but StormFlower leapt to life in his grip. He pressed the triggers, sending three quick shots of spinning, green-tinged energy streaking toward the Nuckelavee's upper torso. The blasts caught it off-guard, sparks flaring across the plated armor.
Nora yelled, "Ren, now!"
The Semblance rippled through him. A calm settled over his face, shadows curling subtly around his figure. Around him, the colors of the battlefield dimmed, graying out, making him almost imperceptible against the ruin-strewn landscape. He darted forward like a whisper, blades flashing while StormFlower discharged again, striking weak points between the creature's grotesque joints.
The Nuckelavee roared, its horse head whipping down. One massive hoof crashed toward him. He crossed his blades, reinforcing with Aura, and the tremor barely shook him. A second later, a burst from StormFlower's high-velocity rounds shredded the tendons near its elbow, slowing its strike.
"Keep moving! Don't give it a pattern!" Onyx barked, parrying a flying chunk of rubble with a slash of violet-shadow energy.
Nora flared Dust behind her boots and shot forward, hammer smashing into the creature's thick foreleg. Sparks and black smoke erupted from the impact, but it barely slowed the monster. Another swing of the arm hurled her into the rubble.
Shadows enveloped her fall as Onyx caught her, eyes narrowing, amethyst glow deepening. "You okay?"
"Just peachy!" she spat, blood and dust streaking her face. "It's bigger than I imagined!"
Ren had already recovered, moving like a wraith through the grayed battlefield. With StormFlower firing in tandem with precise blade strikes, he slashed at exposed tendons and joints while masking his emotional state, avoiding the creature's attention. Each strike chipped away at armor plating, forcing the Nuckelavee to overcompensate with massive, sweeping attacks.
Onyx's halberd flashed, splitting debris midair and striking the Nuckelavee's shoulder, leaving a smoking crater. "Ren, its arms—target the joints! Disable them first!"
Ren nodded, eyes calm and distant, colors muted as the Semblance kept him hidden in plain sight. He dropped low, sliding beneath the creature's torso, blades crossing StormFlower's firing lines to carve precise arcs across vulnerable tendons. One arm slammed to the ground, wedging into a fractured stone column.
"Now!" Onyx yelled.
Ren caught the spear of pure shadow hurled toward him, pivoting to drive it through the trapped arm. The Nuckelavee struggled, shrieking, but the spike held. Its other arm lashed out, only to meet Onyx's halberd striking the ground, releasing a spreading black tendril that ensnared the second limb.
"Pancake!" Onyx shouted.
Nora, still propelled by Dust, launched herself skyward, Magnhild crackling with electricity. She slammed it down onto the creature's equine skull with a thunderous explosion that splintered armor and shook the ruins.
The horse body collapsed, leaving only the rider writhing. Ren leapt forward, colors slowly returning as the Semblance faded, blades glowing with green energy. StormFlower spun one final barrage, synchronizing with his crossed blade strike. The rider's screech ended abruptly as it crumbled to ash, scattering in the wind.
Silence settled. Dust swirled around Nora and Ren, both breathing ragged. Onyx approached, halberd dissolving into shadow.
"You did it," he said quietly.
Nora smiled faintly, grime and tears streaking her face. "We… broke its legs."
"You did more than that," Onyx replied, eyes scanning towards the distance.
He didn't elaborate. He didn't need to.
After the Nuckelavee disintegrated, the change rippled outward.
Across the battlefield, the wild Grimm hesitated.
Not fear—Grimm did not know fear—but something older and more primal stirred within them. An instinct etched into their very existence. A hierarchy written into the dark fabric that bound them to destruction.
The apex had fallen.
The Nuckelavee—the dominant presence that had anchored the swarm, commanded it, defined this territory—was gone.
And when something greater than you is slain, the only truth left is simple:
You do not remain where it died.
One by one, the wild Grimm disengaged.
Beowolves broke from their clashes with Onyx's summoned creatures, snarling once before turning away. Ursai abandoned their charges mid-stride. Beringels pounded their fists into the earth in frustration, then retreated. Nevermores screamed overhead—not in rage, but in withdrawal—as their massive wings beat hard for distance.
Not just from the fight.
From Kuroyuri itself.
They fled through the shattered streets, over rooftops, into forests and ravines, vanishing into the fog-choked outskirts as if the land itself had rejected them. Whatever had killed the Nuckelavee now owned this place—and the swarm would not contest that claim.
Behind them, Onyx's Grimm reacted instantly.
Amethyst eyes flared brighter as they realized what had happened.
Monsieur Pancake reared up and let out a thunderous roar, pounding his chest with enough force to shake nearby ruins. Beowolves lifted their heads and howled in unison, their voices echoing through the broken streets. Lancers shrieked skyward, Manticores screeched, Nevermores cawed sharply as they circled once overhead.
A chorus of victory.
Not mindless noise—but recognition.
The battlefield was theirs.
And at the center of it all—
Ren and Nora stood amid the settling dust.
Nora dropped to one knee first, Magnhild's head resting against the ground as she leaned on it for support, chest heaving. Her arms trembled, every muscle screaming in protest now that adrenaline no longer drowned the pain.
Ren sank beside her, one hand pressed to the earth, the other still gripping his blades. His shoulders rose and fell in slow, controlled breaths—but his eyes were fixed on the empty space where the Nuckelavee had stood.
Gone.
Finally gone.
For the first time since childhood, the shadow that had followed them had nowhere left to stand.
Footsteps thundered toward them.
"REN! NORA!"
Ruby was first to reach them, skidding to a stop and dropping to her knees without hesitation. Her silver eyes shone as she grabbed Nora's shoulders. "You did it! You actually did it!"
Yang barreled in right behind her, laughing breathlessly as she hauled Nora into a crushing hug. "Holy crap, that was AWESOME! Did you see that last hit?!"
Weiss arrived next, already summoning a glyph beneath Ren to steady him as he rose. "Don't move too fast," she said firmly, though her voice wavered with relief. "Your Aura's nearly gone."
Blake crouched beside Ren, placing a steadying hand on his arm. Her ears flicked as she scanned the surroundings—then relaxed when she realized the Grimm were truly gone. "It's over," she said quietly. "They're not coming back."
Jaune and Pyrrha reached them moments later, both visibly exhausted but grinning.
Jaune let out a shaky laugh, hands on his knees. "I—okay, I officially never want to see another one of those things again."
Pyrrha smiled softly at Ren and Nora, pride unmistakable in her eyes. "You were incredible. Both of you."
Nora blinked, then laughed weakly, scrubbing at her eyes with the back of her glove. "Guess… guess the village can finally rest, huh?"
Ren didn't answer right away.
He stood slowly, straightening despite the ache in his body, and looked out over the ruins of Kuroyuri. The broken buildings. The cracked streets. The silence where screams once lived.
Then he closed his eyes.
And bowed his head.
"For everyone who didn't make it," he said softly.
Nora stepped beside him, resting her head against his shoulder. "We didn't forget you," she whispered.
A few steps away, Onyx watched them.
His Amethyst Eyes dimmed back to their usual glow as the last of his summoned Grimm settled, dissolving into shadow one by one—returning to him with quiet obedience. The battlefield felt different now. Lighter. Not safe, perhaps—but no longer cursed.
Ruby turned toward him, grinning wide. "Onyx! That was amazing!"
Yang jabbed a thumb toward Ren and Nora. "You weren't kidding when you said this fight was theirs."
Onyx nodded once. "They earned it."
Jaune looked between Ren and Nora, then back at the ruins. "So… that's it? Kuroyuri's really—"
"Free," Onyx finished.
He stepped forward, stopping beside Ren and Nora. His voice was calm, steady—but carried weight.
"The Grimm are gone. The source is gone. What comes next… is rebuilding."
Ren met his gaze, emotion thick in his throat. "Thank you," he said quietly. "For trusting us."
Onyx's lips curved into a small, knowing smile. "You didn't need my permission."
For a moment, they all stood there together—battle-worn, exhausted, but victorious—amid the ruins of a place that had finally been reclaimed.
Kuroyuri no longer belonged to the darkness.
And its night, for once, was peaceful.
A/N: Hey! Sorry that it took so long, I was busy, anyway I hope you enjoyed this chapter and check out the updated bio of Onyx.