Eren woke to pain.

  Not the sharp kind that faded quickly, but a deep, lingering ache that wrapped around his chest and limbs like iron bands. Every breath felt heavier than the last. The ground beneath him was cold, gritty with ash and broken stone, and for a moment he didn’t remember how he’d gotten there.

  Then the memories came rushing back.

  The ruins.

  The fragment.

  The people who knew his secret.

  Eren tried to sit up.

  Agony flared through his body, forcing a gasp from his lips as he collapsed back onto the slope. His vision blurred, dark spots dancing at the edges.

  The Aether Core pulsed weakly.

  Wrong.

  The rhythm was uneven now, stuttering like a heart struggling to keep pace.

  “What did you do to me…” he whispered.

  No answer came, but the sensation inside his chest twisted sharply, as if reacting to the accusation. Heat surged—then vanished—replaced by a chilling emptiness that made his skin prickle.

  Eren clenched his jaw and focused.

  Slow breaths.

  The warmth returned in fragments, barely enough to steady him.

  Minutes passed before he managed to stand.

  His legs trembled beneath him, and a faint shimmer rippled through the air with every step he took. Shadows bent unnaturally around his feet, lagging behind his movement like something reluctant to let go.

  This wasn’t control.

  It was residue.

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  By the time Eren reached the edge of the Ashen Border, the sun was already climbing high into the sky. The familiar shapes of trees and grass felt unreal, as if he were seeing them through a thin veil.

  Grayhaven lay just beyond the ridge.

  Home.

  He should have felt relief.

  Instead, dread coiled in his stomach.

  The moment he crossed the boundary, the Core reacted violently. A sharp spike of pain shot through his chest, dropping him to one knee. His breath hitched as darkness flooded his vision.

  Stability critical.

  Shadow influence exceeding tolerance.

  Eren froze.

  “That’s new,” he muttered hoarsely.

  He forced himself upright again, every instinct screaming at him to stop using the Core—but the problem was clear.

  He wasn’t using it.

  It was using him.

  He made it back to his room just before nightfall.

  The door shut behind him with a soft click, and Eren leaned heavily against it, sliding down until he was sitting on the floor. Sweat soaked through his clothes despite the chill in the air.

  The shadows in the corners of the room thickened.

  They gathered.

  Eren stared at them, heart pounding.

  “Stay back,” he said quietly.

  They didn’t obey.

  Darkness stretched toward him, not aggressive, not hostile—curious. Familiar. It pressed against his skin like cold smoke, slipping through the gaps in his defenses.

  Pain flared again.

  This time, it didn’t fade.

  Eren cried out as the Core surged wildly, energy spiraling out of control. Images flooded his mind—ruins collapsing, runes shattering, something vast stirring beneath the stone.

  Too much.

  He slammed his fist into the floor.

  “Enough!”

  The word tore itself from his throat.

  For a terrifying second, nothing happened.

  Then the shadows recoiled.

  The pressure lifted just enough for him to breathe.

  Eren lay there, shaking, staring at the ceiling.

  So this was the cost.

  Power without foundation.

  Affinity without mastery.

  He wasn’t growing stronger.

  He was destabilizing.

  When the Core finally settled into a fragile equilibrium, Eren pushed himself up and staggered to his desk. With trembling hands, he lit a small lantern. The warm glow pushed back the shadows, though they lingered just beyond the light’s reach.

  Eren opened his satchel.

  The Core Fragment was gone.

  But something remained.

  A faint, angular mark had appeared on his palm—barely visible, like a scar that hadn’t fully formed. When he focused on it, a dull ache answered back.

  A reminder.

  A claim.

  Eren closed his hand slowly.

  “They won’t stop,” he said to the empty room.

  The people in the ruins.

  The organization behind them.

  Whatever had stirred beneath the Ashen Border.

  He was no longer invisible.

  And worse—he was unstable.

  Eren exhaled, forcing his breathing to steady.

  “If I’m going to survive,” he whispered, “I need control.”

  Outside, the wind shifted.

  Somewhere far beyond Grayhaven, ancient mechanisms turned once more.

  And the path Eren had chosen began to narrow.