Harry stepped fully into the emerald light of the Chamber, cloak clutched in one trembling hand, his other wrapped so tightly around his wand his knuckles glowed white.
He stared at the destroyed diary, the scorch marks in the stone, the lingering wisps of dissipating dark magic.
Then back to Cassius.
He was amazed everyone in the wizarding world knew who Voldemort was, children were read bedtime stories to scare them straight at night afterall.
And Cassius had just fought with the man himself!
"You didn't even hesitate," Harry whispered. "You just—killed him."
Cassius raised an eyebrow.
"He wasn't alive, Harry. He was a memory. A lingering curse."
Harry didn't move.
His breathing was uneven, too loud in the cavernous quiet.
"He was Voldemort," Harry said hoarsely. "Voldemort was here, right now, and you—you took him out like it was nothing."
Cassius didn't deny it.
Harry swallowed again, throat bobbing.
His face twisted in some frantic inner struggle—fear, awe, and something sharp and bitter.
"You—you shouldn't have," Harry said suddenly. "You should've gotten a teacher. Or told me."
Cassius blinked, unimpressed. "Why would i tell you? As i stated before you weren't ready to be here, don't tell me you didnt even know what you'd find down here?"
That hit Harry like a slap.
"You don't get to decide that!" he snapped, voice going shrill. "He came back—again—and I was supposed to be the one to stop him!"
Cassius sighed. "You're twelve. And can hardly win in a duel against your peers."
Harry's jaw clenched.
His eyes flicked past Cassius, to the great stone statue of Salazar Slytherin towering above them.
To the massive chamber.
To the oppressive darkness.
His fear folded inward, becoming desperation.
"The basilisk," Harry said suddenly. "It's still here."
Cassius didn't answer.
Harry had only just learnt what the creature was, but had no idea just what the beast actually was.
But it was simple to guess the giant cocoon nearby Cassius had to be the monster in hiding.
Harry took a shaky breath, then another.
"That thing has been attacking students all year. It petrified Colin—Justin. If we leave it now it could come back. It could kill someone, like it did to Myrtle before."
Cassius remained silent.
Harry tightened his grip on his wand.
"We have to kill it."
Cassius's expression didn't change. "No. We don't."
Harry froze.
Then anger—real anger—flared across his face.
"Why not?!" he shouted.
Cassius finally turned fully toward him, stepping forward so Harry had to tilt his chin up to maintain eye contact.
"Because it isn't attacking anyone anymore. Its orders died with the diary. Without Riddle, it's dormant."
Harry reeled. "You… you're just going to leave a basilisk under the school?"
Cassius smirked. "You say that like the school doesn't already sit on top of a murderous acromantula colony, an entire lake of monsters, not to mention that third floor corridor from last year harboring all manner of deadly dangers."
"That's different!"
"No," Cassius said calmly, "it's really not."
Harry shook his head, frantic, disbelief crumpling his expression.
"If you won't do it," he said, voice cracking, "then I will."
Cassius didn't move.
Harry moved to step past him to approach the waiting chrysalis.
"Don't be stupid," Cassius said.
Harry whipped around. "You don't get to call me stupid! This is my job—my fight! Voldemort came back for me. I have to be able to stop him."
Cassius's eyes flickered with something unreadable.
"You want to prove yourself," he said quietly. "That's all this is. And to do it you're willing to become that which you hate, killing a defenceless baby just to gain yourself glory."
Harry glared, trembling.
"Move," he demanded, raising his wand.
Cassius didn't.
~
Harry's wand hand quivered, but he didn't lower it.
"I'm warning you," Harry said, trying for bravado and landing somewhere closer to pleading. "Move."
Cassius's voice dropped to a chill.
"No."
The air changed.
The chamber seemed to tighten around them, contracting like the throat of some giant serpent preparing to strike.
Harry's breath hitched.
Cassius lowered his chin, eyes gleaming.
"You think killing a basilisk will make you a hero?" he asked softly. "You think it will make you strong?"
Harry's jaw shook. "It has to be done."
"No," Cassius replied. "You just need it to be you."
Harry lunged forward, desperation overriding sense.
"Expelliarmus!"
Cassius flicked his wrist.
"Protego."
The spell shattered harmlessly.
Harry stumbled from the recoil, eyes wide with panic.
He hadn't expected Cassius to block him so easily—he'd half hoped the spell would shock him into moving aside.
Cassius advanced a step.
Harry stepped back.
"You're not thinking," Cassius said. "You're panicking."
"Shut up!"
Harry fired again.
"Stupefy!"
Cassius sidestepped, the red bolt sizzling into the floor where he'd stood.
"You'll die down here," Cassius said, tone almost bored.
Harry raised his wand again—shaking, sweating, furious.
"I won't let Voldemort take anyone else from me!"
Cassius's gaze sharpened.
"Take what from you, he's already been defeated, Ginny's been saved there's nothing left for you to even do hero."
Harry froze.
Cassius had hit the nerve.
Perfectly.
Harry's breathing stuttered. "I—I can't just—"
"You can't stand that it wasn't you," Cassius finished.
Harry's face twisted into something raw—hurt, pride, shame—and he screamed:
"Expelliarmus!"
Cassius countered instantly.
"Depulso."
Harry barely had time to register the spell before it slammed into him, sending him skidding backward across the wet stone floor.
He hit the ground hard, wand slipping from his fingers and clattering out of reach.
He choked on a gasp.
Cassius didn't follow.
He simply stood over him, wand still raised—not threatening, but definitive.
The duel was already over.
Harry crawled for his wand.
Cassius flicked his wrist and sent it skidding farther away.
Harry stopped, chest heaving.
"It's over," Cassius said emotionlessly.
Harry's hands curled into fists.
"You aren't the hero here," Cassius continued. "And killing the basilisk won't change that."
Harry looked up at him with something close to hatred.
Then—
everything faded to black as he lost conciousness.
But to Cassius something had changed, his half-twin was down unconcious upon the ground but from a cut on his brow blood flowed, not much but the blood flowed irregularly.
Not just running down his face, infact it never touched his face.
The blood floated up after leaving through his minor wound, floating in a trail through the air, until the wound naturally clotted, cutting the trail off, but the seeped blood carried on until it connected with Serepha's cocoon and being absorbed.
Then came a CRACK.
Cassius spun to look, according to Lady Draconis the evolution would still take another couple months to complete, but instead the egg if you could call it that had just crack.