Chapter Text
The Slytherin common room was louder than usual that evening.
Not chaotic—Slytherins rarely allowed chaos—but thick with murmuring voices, the rustle of parchment, and the low hiss of strategy forming in corners like serpents coiling together.
Green firelight flickered across the black-tiled floor. Shadows rippled over the silver serpent carved above the mantel. Outside the tall windows, the lake pressed dark and endless against the glass, slow currents shifting like distant ghosts.
At the centre of it all stood Professor Horace Slughorn, round and gleaming with excitement, hands clasped behind his back as he addressed the gathered house.
Every Slytherin from multiple years had crowded in.
Near the back of the room, leaning lazily against the arm of a velvet sofa, stood Regulus Black.
He looked profoundly uninterested.
One ankle crossed over the other. Sleeves rolled halfway to his elbows. A silver ring on his finger glinting as he idly spun a quill between his fingers.
His dark curls were slightly messy from Quidditch practice.
Across the room, Evan Rosier stood stiff beside the drinks cabinet, arms folded, jaw tight.
Next to him, Dorcas Meadowes leaned against the wall, watching everything with sharp, wary eyes.
They both knew exactly where this was going.
And they hated it.
Slughorn cleared his throat dramatically.
“My dear students,” he said, voice booming with theatrical enthusiasm. “As you all know, Headmaster Dumbledore has announced a school-wide competition between all four houses.”
Murmurs of irritation rippled through the room.
Across the chamber a seventh-year scoffed.
“Gryffindor’s already insufferable enough.”
“Ravenclaws think it’s an academic decathlon.”
“Hufflepuffs will probably bring snacks.”
A few students laughed.
Slughorn raised a hand.
“But Slytherin,” he said warmly, “is going to win.”
More murmuring.
Evan glanced at Dorcas.
She gave a small shake of her head.
No.
Please no.
Slughorn’s gaze slowly drifted across the room.
Until it landed on Regulus Black.
The common room quieted.
Regulus didn’t move.
He was still leaning there, looking faintly bored.
Slughorn’s eyes gleamed.
“Well now,” he said pleasantly, beginning to stroll across the room. “There is one particular student among us who may hold the key.”
Several students turned.
Their eyes followed Slughorn.
Straight to Regulus.
Regulus sighed quietly under his breath.
Evan pushed away from the cabinet immediately.
Dorcas straightened.
Slughorn stopped in front of Regulus and smiled like a proud uncle presenting a prodigy.
“Regulus Arcturus Black,” he announced warmly.
Several students clapped politely.
Others stared.
Everyone knew who Regulus Black was.
Star Slytherin Seeker.
Heir to the House of Black.
Oldest pureblood family in Britain.
Ancient magic in the bloodline.
Magic no one else had.
Regulus looked up slowly.
“…Hello, sir.”
Slughorn chuckled.
“So modest!”
He turned to the room, placing a hand on Regulus’s shoulder.
“Now, I realize that you've always been an outcast,” Slughorn said, pacing slowly as he spoke, voice theatrical and coaxing.
Several Slytherins glanced at Regulus.
He frowned faintly.
Slughorn continued smoothly, “It's not everyone at school who likes to think.”
A few older Slytherins nodded approvingly.
“To find a student that's like you, I've had one or maybe two.”
Slughorn sighed dramatically.
“But the good ones disappear before I blink.”
Regulus shifted uncomfortably.
Across the room Evan muttered under his breath.
“Oh this is bad.”
Dorcas whispered back, “Yeah.”
Slughorn leaned closer to Regulus.
“Now, I understand you have your reservations.”
Regulus’s shoulders tightened.
“It's hard to have a brain as large as yours.”
A few students laughed.
Regulus did not.
“But if we don't win these games,” Slughorn continued calmly.
The room had gone completely silent now.
“Well, I think I've made it plain.”
His voice dropped slightly.
“What will happen if we have the losing scores?”
That was when the room changed.
A ripple moved through the students.
And suddenly voices rose around the chamber.
Cold.
Unified.
Pressuring.
Several Slytherins stepped forward.
“Unleash the magic.”
Another voice joined.
“Unleash the magic.”
A third.
“If we lose, then you're to blame.”
Regulus’s eyes widened slightly.
Around him the Slytherins continued.
“They all have used it.”
“Maybe abused it.”
“So then why can't we do the same?”
Dorcas’s hands clenched.
Evan swore quietly.
“Stop,” he muttered.
But no one listened.
Slughorn lifted his hands as though conducting the entire room.
“Call it power, call it magic.”
His eyes gleamed at Regulus.
“If we lose, it will be tragic.”
Regulus’s breathing had grown shallower.
“More important is the knowledge we'll have lost.”
The professor circled him slowly.
“A chance like this won't come again, you'll regret not giving in.”
He stopped directly in front of Regulus.
“Isn't understanding magic worth the cost?”
The Slytherins surged again.
“Unleash the magic.”
“Unleash the magic.”
One of the seventh-years smirked.
“We're not friends here after all.”
Another laughed softly.
“Our only interest in this business.”
Several voices joined.
“Is seeing Gryffindor fall.”
The word Gryffindor drew a low rumble of approval.
Across the room Evan stepped forward.
“That’s enough.”
But the moment he moved three other Slytherins blocked his path.
Dorcas grabbed his arm.
“Don’t.”
Slughorn continued smoothly.
“What I'm suggesting's very simple.”
He gestured broadly to the room.
“And since it's win, win on all scores.”
His hand rested again on Regulus’s shoulder.
“You only want to learn about the magic that you have stored.”
Regulus’s jaw tightened.
“And as for me and all the others, we only want what we deserve.”
Slughorn smiled brightly.
“That our house will clinch the win and my legacy will endure.”
The room erupted again.
“Unleash the magic.”
“Unleash the magic.”
“If we lose, then it's a crime.”
A fifth-year leaned forward eagerly.
“But we can win it if you begin it.”
Another added sharply.
“It's up to you to not fail this time.”
The chant began spreading.
Louder.
Rhythmic.
“Unleash the magic, free the magic now.”
“Unleash the magic, free the magic now.”
“Unleash the magic.”
Regulus’s fingers trembled slightly.
Across the room Dorcas whispered desperately.
“Reg…”
The voices continued.
“Free the magic now.”
Regulus spoke quietly.
“Imagine all I'll learn…”
The room stilled for half a second.
Then the Slytherins answered immediately.
“Free the magic now.”
Regulus swallowed.
“By setting it free…”
They pushed harder.
“Unleash the magic, free the magic now.”
“Unleash the magic.”
Regulus’s voice was softer now.
“And now winning these games…”
Again they answered.
“Free the magic now.”
Regulus closed his eyes briefly.
“…Depends on me…!”
“Unleash the magic, free the magic now.”
“Unleash the magic.”
Regulus looked up slowly.
“And what doors might open.”
The crowd surged closer.
“Free the magic.”
Regulus’s voice cracked slightly.
“If I try to use it—!”
“Unleash the magic.”
“Free the magic now.”
“Unleash the magic.”
Regulus’s hands clenched.
“But the magic's—!”
The students pressed in.
“Free the magic.”
Regulus whispered,
“What I really want to see!”
The room exploded again.
“Unleash the magic, free the magic.”
“Unleash the magic.”
Dorcas shoved through the crowd finally.
Her voice cut through everything.
“Regulus, no…”
But the chant drowned her out.
“Free the magic now!”
Silence fell.
Regulus stood in the middle of the room.
Surrounded.
Every Slytherin staring at him.
Waiting.
Slughorn’s smile gleamed.
Evan’s expression was pure fury.
Dorcas looked like she wanted to drag Regulus out of the room herself.
Regulus looked between them.
Then at the rest of the house.
Then slowly—
he nodded.
A wave of triumphant cheers burst through the common room.
Slughorn clapped his hands delightedly.
“Excellent!”
Across the room Dorcas swore under her breath.
Evan ran a hand down his face.
Regulus didn’t smile.
He just stood there.
And the shadows behind him seemed a little darker than before.
The moment Regulus nodded, the room erupted.
Cheers burst through the Slytherin common room like a storm breaking loose.
Students surged forward, surrounding him in a tightening ring. Hands clapped shoulders. Voices shouted over one another. The green fire in the hearth crackled wildly, shadows whipping across the walls like serpents thrashing in anticipation.
Horace Slughorn looked delighted.
“Marvellous,” he said, voice thick with excitement. “Simply marvellous.”
Regulus stood at the centre of the crowd.
Still.
Too still.
The earlier hesitation lingered somewhere behind his eyes, but it was buried beneath the roaring pressure of the room around him.
Hands pushed him gently but firmly toward the centre of the common room floor.
The furniture had been shoved aside.
Students crowded shoulder to shoulder.
Watching.
Waiting.
Slughorn stepped forward, his expression sharp with eager pride.
“Well then,” he said smoothly. “Let us begin.”
Regulus swallowed.
Across the room, Evan Rosier shoved through a cluster of sixth years.
“This is a terrible idea,” he muttered.
Dorcas Meadowes was already moving.
“Reg,” she called sharply.
But the crowd was tightening now.
They closed ranks around Regulus.
Slughorn placed a steady hand on his shoulder.
“You know the chant,” he murmured encouragingly.
Regulus nodded faintly.
His voice came out quieter than usual.
“…Yes.”
Slughorn smiled.
“Excellent.”
He guided Regulus forward to the exact centre of the stone floor.
The Slytherin students pressed inward, forming a complete circle around him.
The lake outside shifted against the glass windows, sending pale green light rippling across the room.
Slughorn’s hand tightened slightly on Regulus’s shoulder.
“Go on, my boy.”
Regulus drew a breath.
Then he began.
Low.
Ancient words rolled from his tongue, syllables older than Hogwarts itself. The language felt thick and heavy in the air, like the stones themselves were listening.
At first nothing happened.
The students leaned closer.
Waiting.
Then—
The temperature dropped.
A ripple passed through the room.
Regulus’s shoulders tensed.
Slughorn’s smile sharpened.
“Yes… yes, that’s it.”
Regulus continued the chant.
The words grew stronger.
Magic stirred beneath the stone floor.
A faint shadow slid beneath Regulus’s feet.
Dorcas stepped forward sharply.
“Stop.”
Two Slytherins grabbed her arms immediately.
“Wait your turn,” one of them snapped.
Evan’s voice rose.
“Let him go!”
But three older students blocked his path.
The chant grew louder.
Regulus’s voice began to shake.
The shadow beneath him deepened.
A dark swirl spread slowly across the floor like ink soaking into parchment.
Then Regulus gasped.
Pain flashed across his face.
His knees buckled slightly.
Slughorn caught him instantly, gripping both shoulders.
“Steady,” he said firmly.
Regulus tried to pull away.
“Sir—”
“Keep going.”
The professor held him upright.
“Don’t stop now.”
Regulus’s breathing hitched.
The chant resumed.
This time louder.
More desperate.
The shadows twisted harder around him.
A sharp crack of magic snapped through the room.
Students screamed in excitement.
“Look!”
Regulus’s eyes flared—
Pure white.
Magic burst from his hands in jagged streams.
White light poured from his fingertips like lightning leaking through his skin.
The room shook.
The stone floor trembled violently beneath their feet.
Regulus screamed.
The sound tore from his throat raw and uncontrolled.
His knees hit the floor.
Evan lunged forward.
“REG!”
Three students slammed into him, holding him back.
Dorcas struggled violently.
“LET HIM GO!”
Slughorn still held Regulus upright.
“Keep chanting!”
Regulus’s entire body shook now.
The magic pouring from his hands turned darker.
The shadows coiled tighter.
The stone beneath him exploded with light.
A massive magic circle ignited under his body.
Ancient runes burned across the floor in blazing silver fire.
The circle spun.
The entire common room rattled.
Glass windows shuddered violently against the lake outside.
Books flew from shelves.
Students screamed and laughed at the same time.
Energy spiralled upward around Regulus like a storm.
His scream grew louder.
Then suddenly—
Silence.
The magic vanished.
The circle faded.
The room stopped shaking.
Regulus collapsed.
Dorcas screamed.
“REGULUS!”
Evan shoved through the crowd this time, pure panic on his face.
But the students shoved them both backward again.
“Wait!”
“Don’t interfere!”
“Let’s see!”
Regulus lay motionless on the floor.
The room held its breath.
Then—
He moved.
Slowly.
Regulus’s fingers twitched.
His shoulders shifted.
He pushed himself up slightly.
His head lifted.
And when his face came into the firelight—
Everyone froze.
His expression was blank.
Completely empty.
His eyes were still glowing.
White.
Pure white.
No pupil.
No iris.
Just burning light.
A quiet murmur spread through the room.
Then slowly—
The white faded.
Colour returned.
Grey eyes.
Familiar again.
But not quite.
Regulus tilted his head slightly.
Then he smiled.
It wasn’t the same smile.
There was something sharp in it.
Something cold.
He stood slowly.
The room watched him like spectators at the edge of a cliff.
Regulus lifted one hand.
His fingers flexed experimentally.
The tips of them had turned black.
Not stained.
Changed.
Magic curled around them like smoke.
Regulus let out a quiet breath.
“…Well.”
His voice sounded different.
Smoother.
Sharper.
He flicked his wrist.
A spark of dark magic snapped through the air.
Students gasped.
Then the cheering began.
Louder than before.
The entire room erupted.
“YES!”
“Did you see that?”
“He did it!”
Slughorn clapped his hands in delight.
“Magnificent!”
Students crowded forward eagerly.
Regulus rolled his shoulders slowly.
He looked… pleased.
A little amused.
His smirk widened.
“Interesting.”
He flexed his fingers again.
More magic curled around them.
Across the room, Evan stared.
His stomach dropped.
“That’s not him.”
Dorcas whispered,
“Oh no.”
Slughorn approached Regulus with gleaming eyes.
“My boy,” he said proudly. “How do you feel?”
Regulus looked down at his hands.
Then he laughed softly.
“Powerful.”
The Slytherins roared in approval.
Dorcas grabbed Evan’s sleeve.
“We have to fix this.”
Evan’s voice was tight.
“How?”
Regulus glanced across the room.
His gaze passed over them briefly.
For a moment—
There was nothing in his eyes.
Just cold curiosity.
Dorcas felt something twist in her chest.
Evan pulled her toward the door.
“We’re getting help.”
Neither of them looked back.
Behind them, the Slytherin common room rang with celebration.
And Regulus Black stood in the centre of it all.
Smiling.