?Chapter 18: The Price of Inertia and the First Crack

  ?The winter sun of Morgathia was a pale blade that brought no warmth; it only revealed the misery of the training courtyard. Ren felt every fiber of his body as if it had been ground between two millstones. The contained awakening from the previous night had left a trail of cellular exhaustion that no training in the 14th BIL could have prepared him for. His mana channels, now forced to maintain a "low voltage" flow to avoid alerting the runic collar, throbbed in a funeral rhythm.

  ?He was standing, but his mind was in a tactical fog, processing the data from his new core while trying to maintain his slave posture. That was when the world spun.

  ?BAM!

  ?Eduard’s reinforced leather boot struck Ren’s solar plexus with the force of a battering ram. The air was expelled from his lungs in a sharp wheeze. Ren’s six-year-old body was launched backward, skidding through the dirty snow until he slammed against the base of a granite statue.

  ?"Why are you lagging so much, you useless brat?!" Eduard’s voice echoed, dripping with an arrogance that bordered on psychopathy. He walked up to Ren, hands on his hips, looking down at him. "I paid gold for a combat encyclopedia, not for a ragdoll that sleeps on its feet. I want to get stronger! Wake up, you weakling!"

  ?Ren struggled to inhale. The pain in his gut was an explosion of agony, but his sergeant’s mind was already performing triage. "Ribs intact... diaphragm in spasm... internal bleeding unlikely... focus, Keinji."

  ?The Missing Link: The Doctrine of Pain (Flashback)

  ?As Ren’s vision darkened, he saw himself back in Eritineos, in the year when everything seemed possible. He was five years old, sitting in the library with his brother Leon. Leon, the heir of shadows, was cleaning a dagger, while Ren flipped through a Valerius lineage medical journal that Arthur had let him read under supervision.

  ?"Pain is a calculation error, Ren," Leon had said that day, without taking his eyes off the blade. "If you feel pain during a movement, it means your energy is hitting a wall. The secret of great generals isn't ignoring pain; it’s using it as a flow sensor. If it hurts here"—Leon pointed to his own wrist—"you move the vector over there."

  ?Leon looked at his younger brother with uncommon seriousness.

  ?"Never let the enemy know it hurts. The moment you show agony, you hand over the map of your weakness. Transform pain into processing fuel. Use the shock to accelerate your reflexes, not to lock them up."

  ?The Now: The Vermilion Courtyard

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  ?Ren spat a bit of blood-tinged saliva into the snow. He stood up slowly. Every movement was an insult to his nerves, but he applied Leon’s "Doctrine of Pain." He didn't look at Eduard with visible hatred; he looked at him with the coldness of a technician observing a defective part.

  ?"I ask for your forgiveness, Young Master Eduard," Ren said, his voice coming out low but perfectly steady. The collar on his neck gave a warning crackle, sensing the mana fluctuation caused by the impact, but Ren stifled it using Silas’s technique. "Last night’s adjustment was... intense. Let us continue."

  ?Eduard smirked, satisfied with what he considered submission.

  ?"Good. Show me the high-frequency rotation again. I feel like I’m almost piercing through steel."

  ?Ren took his position. He instructed Eduard to concentrate mana in his right forearm, inducing the "Hyperbolic Spiral" technique he had been teaching for weeks. Ren knew Eduard’s body was at its limit. The inflammation in the young noble’s mana channels was at its peak; the walls of the protein filaments were as thin as tissue paper due to the constant friction.

  ?"More speed, Young Master," Ren urged, acting like a firing range instructor. "Do not fear the heat in your arm. It is merely power manifesting itself."

  ?Eduard shouted, channeling an absurd amount of mana. The air around his fist began to swirl, creating a visible vacuum. Julius, watching from afar, narrowed his eyes, impressed.

  ?"Now! Fire!" Ren ordered.

  ?Eduard launched his punch into the air toward an iron target.

  ?CRACK.

  ?The sound didn't come from the target. It came from inside Eduard’s arm.

  ?The scream that followed was of a different nature. Eduard fell to his knees, clutching his right forearm. The limb was pale, and tiny burst veins began to form purple blotches under the skin.

  ?"MY ARM!" Eduard bellowed. "It feels like... like there are needles of fire running inside my bones! What did you do, you bastard?!"

  ?Marth Vermilion stood up from his throne, hand on his sword hilt. The Duke’s flame aura began to leak, making the air heavy.

  ?Ren did not flinch. He maintained the expression of technical concern he had practiced in front of the mirror back on Earth when he needed to explain a logistics error that wasn't his fault.

  ?"It is Adaptation Fibrosis, Milord," Ren said, bowing slightly to the Duke. "I warned that the body needs rest to heal the runic channels. Young Master Eduard has such overwhelming talent that his own mana is outstripping his nerves' healing speed. It is the price of genius. If he stops now and rests for three days, the arm will become stronger than ever. But if he continues... the channel will rupture permanently."

  ?It was the perfect lie. Ren was calling a degenerative injury "proof of talent."

  ?Marth paused. Pride for his son’s "overwhelming power" overcame suspicion.

  ?"Eduard, stop. Julius, take your brother to the infirmary."

  ?Julius approached, but before grabbing his brother, he cast a long, piercing look at Ren. The third Vermilion son wasn't as impulsive as the second. He felt there was something wrong with the "geometry" of that technique, but he couldn't prove it.

  ?When the courtyard was empty, leaving only Ren and the blood-stained snow, he allowed himself a small internal smirk. The kick to the gut had been paid back with interest. Eduard’s mana circulatory system had just suffered its first catastrophic micro-rupture.

  ?Ren felt his own collar tighten. Pain was his constant companion, but now he had one certainty: he wasn't the only one suffering in that castle.

  ?"One crack a day, Eduard," Ren thought, walking back to the dungeon with trembling hands. "Until your logistical system is so broken that you can't lift a spoon, let alone a sword."