The clang of steel doors echoed down the cold stone corridor. Kaien's breath misted faintly in the mountain air as two butlers ushered him into the underground chamber. He had been here before, though never as a participant.
The Training Pit.
The torches on the walls gave off wavering orange light that did little to warm the chamber. The ground was packed earth, scarred with cuts and gouges from countless battles. Above, carved balconies formed a ring where members of the Zoldyck family often sat and watched.
Tonight, Silva stood there with arms folded, massive frame like a statue carved from pale marble. Beside him, Zeno leaned against the railing, long mustache twitching, amusement alive in his sharp eyes. Kikyo's parasol rested on her shoulder, her smile thin and cold.
And down in the pit, Kaien saw Illumi. His cousin stood barefoot, hair falling around his pale face, expression blank as ever. He raised his eyes to meet Kaien's, and in that silence, Kaien knew: this was not a spar. This was a test.
"Family sharpens family," Silva's voice boomed from above. "No assassin grows strong in comfort. Kaien, Illumi—fight. No mercy. Stop only when I command it."
The words dropped like stone. Kaien's heart thrummed against his ribs, but his face remained calm. He stepped onto the earth, long hair brushing across his shoulders.
Illumi tilted his head slightly, as though studying Kaien not as kin, but as prey.
The air between them grew heavy. Kaien felt his aura stir, unsteady but present—Ten wrapping around his body, the lesson Zeno had drilled into him since his first kill. He imagined it tightening like a sheath, sealing his energy to his skin.
Illumi moved first. He blurred across the pit, faster than Kaien had expected. His nails lengthened, sharp as needles, gleaming faintly in the torchlight. Kaien barely raised his twin blades in time, sparks flying as steel rang against hardened nails.
He's faster. But I'm stronger.
Kaien twisted, muscles bunching, forcing Illumi back with sheer physical power. But Illumi flowed like water, slipping aside, eyes always steady, unreadable.
"You're leaking," Illumi murmured, barely audible.
Kaien realized too late his aura had slipped. His Ten faltered in his anger, spilling from his shoulders in ragged wisps. Illumi's nails flicked forward, stabbing for the opening.
Instinct screamed. Kaien pulled inward, slamming his aura tight again, the strike glancing harmlessly off the thin veil of Ten. His heart pounded. His mind raced.
Zeno's chuckle drifted down from above. "Good, good. He remembers. Even cornered."
Kaien exhaled, forced his focus back. Calm. He's not just testing me. They're all watching how I react.
Illumi circled slowly, never rushing now, like a predator wearing down prey. His eyes flickered to Kaien's trembling hand and back again. "You killed once. But can you kill blood?"
The words were not a taunt. They were simple, factual.
Kaien's grip tightened on his blades. He had killed a stranger. Killing kin… was different. But Silva's gaze weighed on him like iron. In the Zoldyck family, hesitation was weakness. Weakness was death.
Illumi came again. This time Kaien met him head-on, aura flaring stronger, wrapping around his weapons, his arms. The clash rang louder. He forced Illumi back step by step, every muscle in his tall frame straining.
And yet Illumi's face never changed. Not fear, not anger, only calculation.
Finally, Silva's voice cut through the chamber. "Enough."
Both froze instantly. Illumi's nails retracted. Kaien's chest heaved with the effort of control.
Silva's eyes lingered on Kaien, unreadable. "You held your aura. You adapted. You live another day."
Kikyo's parasol twitched as she smiled faintly. "Such lovely boys."
Zeno clapped once, sharp and amused. "He learns fast. But not fast enough. We'll fix that."
Kaien bowed his head. "Yes, Grandfather."
The following weeks blurred into agony.
Zeno forced Kaien to sit motionless for hours, aura pressed close to his skin, sweat dripping into his eyes. "Ten is patience. Ten is discipline. Lose focus, and the world eats you."
When Kaien faltered, Zeno would strike him with sudden bursts of his own aura, suffocating waves that made Kaien's bones creak. "Hold. Hold, damn you. If you can't hold under pressure, you're already dead."
At night, Silva tested him differently. Weighted chains hung from Kaien's arms as he practiced strikes, aura flaring to keep his muscles from tearing. "Strength without Nen is hollow," Silva said, voice rumbling. "Nen without strength is air. You will have both."
Illumi watched often. Rarely spoke. But when Kaien stumbled, Illumi's faint voice would surface like a blade in water: "You're letting it leak again." Or, "You thought too much about the trembling."
Kaien hated how accurate he always was.
And yet, beneath the cruelty, there was a strange recognition. Silva did not praise. Zeno only laughed. But they did not dismiss him. They pressed him harder because they saw he could endure it.
One night, Kaien sat cross-legged in the meditation chamber, the lanterns flickering low. His aura clung tightly to his form, thinner now, steadier.
Ten. Just Ten. Keep it in. Don't let it go.
But another lesson gnawed at him. Zeno had whispered of the next step. Zetsu.
To close the nodes completely, to vanish. To become invisible, scentless, aura dead.
Kaien tried. He imagined sealing himself, shutting the floodgates. For a moment the flicker dimmed—then burst outward uncontrolled. He groaned, clutching his temples.
"You'll learn," Zeno had said earlier that day. "It took Illumi months. You? Maybe longer. Maybe shorter. The only way is through pain."
Kaien breathed slowly. Tried again. Failed. Tried again. Failed. His body shook with exhaustion, but he refused to stop.
If I can't disappear, I'll always be a target. I need this.
Finally, on the hundredth attempt, the flicker dimmed—and stayed dim. His aura sank into silence, gone to any observer. For the first time, Kaien felt empty. Hollow. Hidden.
A thrill ran through him.
He opened his eyes—Illumi stood in the doorway, unreadable as ever.
"You finally vanished," Illumi said quietly.
Kaien managed a tired grin. "Took long enough."
Illumi tilted his head. "Don't smile. They'll only raise the bar higher now."
He turned and left.
Kaien stared after him, grin fading. The truth was heavy: in the Zoldyck family, every step forward was rewarded not with rest, but with sharper blades.
And yet, deep inside, he welcomed it.
Because each lesson, each trial, each clash with Illumi brought him closer to what he was becoming.
Not just Kaien Zoldyck, the cousin.
But Kaien Zoldyck, forged in silence, tempered in blood.