Severus Snape arrived with his usual flair for the dramatic, his heavy black robes snapping around his ankles like the wings of a giant bat. He didn't say much—he rarely did when he was impressed—but as he stood over the gaping maw of the pipe, his dark eyes were working overtime. He was dissecting the situation, trying to figure out how a "Muggle Studies" teacher had managed to stumble onto a secret that had eluded the greatest minds of the wizarding world for ten centuries.
"Quite a mess you've made of the plumbing, Sebastian," Snape drawled, his voice like silk dragged over gravel.
Sebastian leaned against a sink, looking entirely too relaxed for someone standing over a monster's lair. "Oh, you know me, Severus. I've always believed in hands-on learning. Though I suppose you're just here to make sure I don't accidentally walk off with any rare potion ingredients without your supervision?"
Snape's lip curled in a familiar sneer. "Someone has to ensure the school isn't dismantled for 'souvenirs.' I had assumed you'd have a fleet of reporters here by now. Surely the Daily Prophet would pay handsomely for a shot of the 'Great Swan' peering into a drainpipe."
"The day is young," Sebastian chuckled.
Just then, Professor McGonagall hurried into the room, her hat slightly askew and her face pale with worry. "Sebastian! The students... they're telling tales about a Basilisk! Is it true? Is this actually it?"
"It is, Minerva," Sebastian said, his tone shifting to one of professional calm. "But the corridor is becoming a hazard. There are about fifty students outside trying to see if I've been eaten yet. Could you please maintain a perimeter? We can't have anyone 'accidentally' falling in."
He turned back to the pipe and gestured toward the darkness. "As for the dirty work, Severus and I—as the resident Slytherin experts—will handle the exploration. It's a family matter, after all."
Snape didn't wait for a formal invitation. Without a word, he stepped into the pipe and vanished, his robes following him like a trailing shadow.
"Always has to be first," Sebastian muttered, and then he jumped.
The descent was a dizzying series of slides and turns. Sebastian didn't fancy getting his robes covered in slime, so he cast a silent Aresto Momentum and a Wingardium Leviosa on himself, drifting down the final stretch like a feather. He landed on a floor littered with the bones of small animals—centuries of snacks for a very large predator.
Snape was already standing a few yards away, a ball of blue fire hovering in his palm. The light cast long, flickering shadows against the damp stone walls. "We are miles beneath the castle," Snape observed, his voice echoing. "Likely under the lake bed. It's a miracle the structure hasn't collapsed under the pressure."
Sebastian pulled out a handkerchief and performed a quick Scourgify on his boots. "Slytherin was a genius, Severus. A bit of a narcissist, sure, but he knew how to build things to last. Now, let's get some proper light in here. I didn't come all this way to squint."
He reached into his extension bag and pulled out a dozen enchanted lanterns. With a flick of his wand, they took flight, spacing themselves perfectly along the ceiling of the tunnel. The white, magnesium-bright light turned the eerie cave into a well-lit hallway.
"Preparation is the difference between an adventurer and a corpse," Sebastian said, winking at Snape's sour expression.
They walked deeper into the gloom. Suddenly, Snape stopped dead. Ahead of them, coiled like a discarded mountain range, was a giant, translucent green skin. It was at least twenty feet long, the scales as large as dinner plates.
Snape knelt beside it, his fingers tracing the edge of the shed skin. "This is... substantial. If the skin is this size, the creature itself must be monstrous. Sebastian, why am I here? A wizard of your... 'reputation'... could surely dispatch a snake by himself."
Sebastian nudged him with an elbow. "Where's your sense of wonder? This is the heart of our House, Severus! Besides, if I find something incredible, I need a witness who isn't a star-struck teenager. And let's be honest, you're the only one here who won't faint if we find a pile of bodies."
He grabbed the skin and shoved it into his bag. "Top-tier material. This will make some incredible dragon-hide—well, basilisk-hide—armor later. I'll even let you have first dibs on the organs if you play nice."
Snape's eyes narrowed. "You speak as if the beast is already a rug. Do you intend to kill it?"
Sebastian stopped and looked at him as if he had suggested burning a library. "Kill it? Severus, where is your business sense? This is likely the last Great Basilisk in Britain. Do you have any idea how much an ounce of fresh, undiluted Basilisk venom goes for on the black market? It's more expensive than unicorn blood!"
Snape blinked. The Potion Master's brain was clearly running the numbers.
"Think of it as sustainable farming," Sebastian continued, his eyes sparkling with greed. "Poor thing has been starving down here on a diet of rats and the occasional lost cat. I'm going to relocate it to a nice, comfortable sanctuary. In exchange for room and board, it can provide us with regular deposits of venom, blood, and skin. It's a win-win."
"You are a terrifying man, Sebastian," Snape muttered, though his pace quickened. "Just tell me I get a twenty-percent cut of the venom for my private stores."
"Thirty, if you help me carry the loot," Sebastian countered.
They reached the final door—a massive stone wall carved with seven intertwined serpents. Snape stepped back, crossing his arms. "Well? I assume you have the password, or do we start blasting?"
Sebastian didn't answer. He closed his eyes, visualizing the diary, the hissing sounds of the bathroom, and the cold authority of a Founder. He opened his mouth and let out a series of low, vibrating rasps.
"Speak to me, Slytherin, greatest of the Hogwarts Four."
The stone snakes began to writhe. The wall didn't just open; it disintegrated into a mist of magic, revealing a chamber so vast it could have housed the Great Hall twice over. Rows of towering stone pillars carved with serpents led the way to a giant statue of a man with a monkey-like face and a long, flowing beard—Salazar Slytherin himself.
"Wait here," Sebastian whispered. "The eyes are the problem. I'll handle the heavy lifting."
He didn't need to see to know where the beast was. He could feel the weight of its magic, a cold, ancient presence stirring at the base of the statue.
"Kill... intruder... kill..." The hiss echoed through the chamber.
Sebastian didn't flinch. He kept his eyes shut, relying on his sensory perception. He felt the air move as the giant head emerged from the statue's mouth.
Zap-zap!
Two precisely aimed Jinxes of the Blind Eye streaked through the air. The Basilisk let out a scream that sounded like grinding metal as the magic struck its orbs. It thrashed, its massive tail smashing a pillar into dust, but it couldn't see its target.
Then came the cold. Sebastian tapped into the ambient moisture of the underground chamber, flash-freezing the floor and the lower half of the serpent's body. The Basilisk hissed in agony as a thick layer of frost encased its scales, pinning it to the ground.
While the beast was incapacitated, Sebastian summoned a custom-made, magically reinforced blindfold from his bag. It snapped into place over the snake's eyes, held by a permanent sticking charm.
"And for the final touch," Sebastian muttered.
A crate of Draught of Living Death—hundreds of vials—flew toward the snake's open maw. Sebastian used a switching spell to empty the liquid directly into the creature's throat. Within seconds, the thrashing stopped. The Great Basilisk of Hogwarts slumped against the stone, entering a deep, chemical hibernation.
Sebastian opened his eyes and wiped a bead of sweat from his forehead. He turned back toward the entrance, where Snape was standing with his wand drawn, looking genuinely stunned.
"Harvest time, Severus!" Sebastian called out cheerfully. "Come on, help me check the statue. I'm sure Salazar didn't just leave a snake down here. There has to be a library or a vault somewhere in that beard."