Blue flames lit the central island brightly. Cold mist rose from the encircling lake. Phosphorescent glow shimmered on the potion inside the stone basin. Condensation already beaded the sides of the goblet Transfigured from a pebble.
Sirius stood before the basin. His throat worked. He glanced at Dumbledore and Melvin—wanting to say something final, but the words wouldn't come.
The real locket had long been swapped. What remained in the basin was only Regulus's decoy. Still—he needed to retrieve it. Needed to recover his brother's body. Nothing that belonged to Regulus should stay in this filthy, lightless place.
Melvin and Dumbledore flanked him, still studying the basin and the Dark magic woven through the cavern.
Dumbledore's gaze drifted across the lake—down to the densely packed Inferi below. His expression was complicated, eyes faintly distant. Grindelwald had once dreamed of raising an Inferi army with the Deathly Hallows. This… was a grotesque echo of that ambition.
Melvin focused on the potion trap itself. According to Kreacher, retrieving the locket required someone to drink the basin dry.
"Sirius," he said quietly, "this isn't a good plan. The potion will cloud your mind, cause excruciating pain, drive you to unconsciousness and straight into the lake. No one could finish it through sheer willpower."
"Then force it down my throat!" Sirius snarled.
As he scooped a gobletful and raised it to his lips, Melvin caught his wrist.
"I'm saying you're a wizard. You should break one spell with another—not drink poison like a fool."
Sirius blinked, confused.
Melvin reached into his coat pocket. Despite its ordinary appearance, metallic clinks and rustles sounded from within—like rummaging through a small warehouse. He pushed aside sweets and snacks, finally pulling out a plain black wooden box.
The creature inside sensed the surrounding emotions. It thrashed uneasily, making the box vibrate.
"A Boggart?" Dumbledore recognised the signature at once.
Sirius stood frozen—goblet of glowing poison still in hand—neither drinking nor pouring it away.
"Boggarts are peculiar creatures," Melvin explained. "They take the shape of whatever their victim fears most. But the form isn't mere illusion—it carries real physical properties."
He tapped the box lightly with his wand, undoing the anti-unlocking charms.
"Real, tangible flesh. Magic that can be sensed. Behaviour dictated by the fear-memory it draws from."
Dumbledore's face lit with approval. "Voldemort's trap demands that someone drink the potion. A Boggart's transformation should fool the magic."
While he spoke, Melvin had already opened the box and cast a False Memory Charm—imprinting his own will onto the creature.
The lid flew back.
A thin figure crawled out.
"Another Young Master Sirius?" Kreacher's eyes widened in disbelief.
The elf who both revered and despised his master—the rebellious prisoner who'd defied the Mistress, spat on pure blood, driven his parents to early graves—now saw two of him. One stood dazed beside the basin, holding poison. The other stepped calmly from the box.
The duplicate moved slowly toward the basin—as though intending to snatch the goblet.
"Melvin! Levent!" Sirius finally reacted. "Can't you give the bloody thing a different face? Get it away from me! It's not going to attack me, is it?"
Melvin ignored him. He watched the Boggart closely—feeding it false fear-memories, coaxing it toward the poison. He wasn't certain whether the potion would affect it normally, or whether the two magics would simply cancel each other.
The Boggart didn't rush the basin. Instead its long, knuckly fingers took the goblet from Sirius's hand. It stared into the glowing green liquid for several seconds.
Then it drank.
The body began to shake. Brows knit in agony. But the Boggart obeyed instinct—turning Melvin's planted fear into reality. Eyes squeezed shut. It reached back into the basin. Another full goblet. Down it went.
Three cups in total. The body could no longer stand. It staggered forward—collapsed across the basin. The potion burned like molten fire through its insides. The shape flickered—almost lost cohesion. Chest heaved. Laboured breathing echoed through the cavern.
Sirius instinctively stepped back—as though he could feel the pain himself.
Whether real or imagined, the Inferi below seemed to stir. The cavern grew colder. Gooseflesh rose on every arm.
"Now what?" Sirius swallowed hard.
The drinking had paused.
The Boggart's eyes remained tightly shut. Face twitching—changing—as though trapped in a terrible nightmare. Muscles slackened. The goblet slipped from limp fingers.
"Force the rest down its throat," Melvin said quietly.
Sirius steeled himself. Approached. Took the falling goblet. Scooped another measure. Pried open the duplicate's jaw. Poured.
"Merlin's name, this is fucked-up," he muttered. "Feels like I'm poisoning myself."
"I don't… want… stop…"
The voice came from the Boggart's mouth—same face, same body—gasping, pleading. But the tone was so broken, so weak, Sirius barely recognised it as his own. He had never imagined himself sounding so terrified.
He stared at the pale, familiar face. Hesitated.
Then gritted his teeth and kept pouring.
"No… I don't want…"
"Let go… stop…"
"Make it stop—make it stop!"
Cup after cup went down. The Boggart curled into a ball—limbs thrashing wildly. Fists pounded stone. It nearly threw Sirius off. He had to pin the arms and legs to continue.
"No… Mother… Regulus…"
"James… I'm not—I'm not—"
The terrified expression suggested unseen phantoms tormenting the body. Groans rose and fell—low, then shrill—echoing across the silent lake.
Five full minutes. Twelve cups. The basin finally ran dry.
Sirius released the Boggart and collapsed beside it—face bloodless, drenched in cold sweat, shaking uncontrollably. Even facing Dementors in Azkaban had never left him this rattled.
The Boggart lay motionless—still wearing Sirius's face. Eyes closed. Mouth slack. Yellowed teeth crooked.
Just when they thought it was finished, eyelids fluttered. A heavy, rattling breath escaped.
"Water… water…"
"Was… Regulus in this much pain too?"
Sirius's emotions were a tangled mess. Almost without thinking, he Summoned a goblet of clear water.
But the instant he brought it near the Boggart's lips—the water vanished.
"Kreacher knows where water is! Kreacher knows!" The elf burst into tears. He flung himself at the lake—scooped a handful of black water—ran back spilling it everywhere—and clumsily poured the filthy liquid over the Boggart's face.
"That's enough."
Melvin's voice cut through. A loud crack of the Switching Spell followed.
The Boggart's limbs shortened. Black fur sprouted. In seconds it became a large black dog—panting hard—scrabbling back into the box.
Kreacher's face turned ashen. He'd disturbed the Inferi. A pale, bloated hand clamped around his ankle. The lake surface erupted—violent churning. More hands rose—linked to more bodies—dragging the elf downward.
Melvin turned. Pale, corpse-white faces everywhere—emerging from the black water. Men. Women. Children. All in tattered clothing. Empty eyes fixed on them. Slow. Inexorable. Leaving wet trails across stone.
"Indeed… all Muggles Voldemort murdered," Dumbledore murmured.
"Let them rest." Melvin's wand-tip kindled a thin flame.
"Wait—Melvin, wait!" Sirius's voice cracked with panic. "Regulus is still in there!"
Melvin paused. Lowered his wand horizontally.
Point Me.
The spell normally indicated true north. Compared to the waves and their entry path, north clearly lay across the lake. Yet the wand spun wildly—ignoring direction—searching through hundreds of corpses for one specific soul.
The tip snapped still—pointing just behind Kreacher.
A gaunt, dark face floated half-submerged. Empty, sunken sockets. Swollen features twisted in permanent malice.
"Found you, Regulus," Sirius whispered.
He flicked his wand. A dozen white binding beams shot out—rapid-fire. Stone curses petrified Inferi on contact. The sheer force bowled others aside.
The drag on Kreacher slowed. The lake boiled harder. Sirius kept casting—relentless white lances piercing the dark—lighting the cavern like cold lightning. His voice rose to a raw shout.
"Dumbledore—Melvin—help me!"
A storm of spells answered. Two legendary wands swept forward—silent incantations. A deluge of magic carved a path through the corpses. Sirius charged straight into the mass—saw Regulus swimming toward him.
Instinct. Nothing more. But to Sirius it felt like intent—like reaching.
Another figure dove in beside him—Kreacher—seizing Regulus's body.
Together they broke the surface. Dragged the corpse onto the island.
Perhaps the body hadn't steeped long enough. Perhaps some faint remnant of will lingered. Regulus barely struggled.
"His body has family to take him home," Dumbledore said quietly. "The rest… have no one left to claim them."
He raised his wand overhead. Firelight danced in blue eyes.
Fiendfyre.
The Elder Wand erupted in golden flame. Whirlwinds of fire spiralled through the cavern—magnificent burning clouds. Superheated steam roared like thunder. The whole island trembled.
On the opposite side a serpent of Fiendfyre plunged into the water—like a fragment of sun falling into the deep. The lake exploded. White steam billowed outward—carrying flame in every direction. Inferi ignited—consumed.
Roaring heat swept the cave. Air screamed through fissures—like anguished howls. Or perhaps… relieved sighs.
The last flame guttered out.
The lake had boiled dry. No Inferi remained. Only a thin layer of grey-white bone ash coated the bottom.
"It's over."
Sirius exhaled long and ragged. No joy—just exhaustion. He sank to the ground. Turned to look at Regulus. The body still twitched faintly. Eyes empty.
Melvin reached into the empty basin. Lifted the locket. Held it out to the stunned Sirius.
Thirteen years ago Regulus had risked everything to swap the real Horcrux for this fake—leaving Voldemort's trap empty. Whatever his reasons—he had defied the Dark Lord. A single ordinary wizard had broken the plan of the most powerful Dark wizard alive.
Sirius took the locket with shaking hands. Studied it.
Compared to the genuine article, this fake was smaller—lacking intricate engravings or Slytherin's mark. It opened with a simple press.
Empty—except for one folded note.
…
To the Dark Lord,
I know I will be dead long before you read this,
but I want you to know that it was I who discovered your secret.
I have stolen the real Horcrux and intend to destroy it as soon as I can.
I am prepared to die to make sure you are mortal once more.
R.A.B.
The paper had yellowed. Neat, elegant handwriting—Slytherin's star pupil.
Beside it lay the locket—photo compartment empty.
Later—back at Grimmauld Place, around the wide round table—Sirius found an old photograph of his brother. Carefully cropped. Placed inside the locket that now symbolised courage and sacrifice.
Melvin and Dumbledore sat a short distance away—studying the genuine locket.