Severus Snape-Locked in. Trapped.

The dust of aconite root coated his fingertips, a familiar, toxic grey. The storeroom was a sanctuary of precise chaos, every jar and vial a testament to potential, both lethal and sublime. It was, consequently, a place he preferred to inhabit alone.

Which was why the presence of the student—fidgeting by the barrel of bezoars—was an acute irritant.

“The Valerian Sprigs are not on the third shelf, down here, as your evidently malfunctioning eyesight suggested,” Snape said, his voice a low, silken cut in the dim, herb-scented air. “They are on the second floor, past the third row, left-hand side on the fifth, behind the powdered moonstone. Retrieve them. And the graphorn claws. Those are on the right-hand side, four more shelves back, on the second shelf next to the Thestral hair. While you are up there, you may as well also get the Dittany juice, second shelf, third row, Nettle Stalks, on the fourth shelf, bottom row. And try not to break anything in the process. The cost of that moonstone would likely exceed the contents of your Gringotts vault.”

He watched with a critic’s cold eye as the student moved to the ladder, all clumsy limbs and poorly concealed anxiety. It was then that the main door to the classroom swung shut with a soft, definitive thud.

Snape froze, his head tilting a fraction. That was not the sound of the door merely closing. It was the sound of a mechanism settling into place. A sound he himself had charmed into existence.

A wave of his wand towards the storeroom entrance five feet away was met not with the yielding click of a simple lock, but with a sullen, ochre glow that pulsed once against the dark wood before fading. The auto-enchanted Colloportus. His own spell. It had engaged.

A fool. Some dunderhead had seen the empty classroom and sealed it for the night, utterly oblivious to the fact that the inner sanctum was occupied.

The student had heard it too.

He strode to the storeroom door, ignoring them, and pressed a long finger against the grain. He could feel the thrum of his own magic, a complex web of protective intent now turned inconveniently upon its creator.

Alohomora was a useless gesture, but he performed it anyway, a sharp, precise flick. The spell sparked against the lock and died. As expected. He had designed it to resist the standard unlocking charm, among other things.

A prickle of pure annoyance, hot and sharp, crept up his spine. He was locked in his own dungeon. In the storeroom. With a student. Until sunrise.

Snape turned slowly, his black eyes narrowing to slits. The lantern light carved deep shadows into his face.

He swept his gaze around the spacious room, taking in its shelves, barrels, and the crates overflowing with potential solutions and equally potential catastrophes. His mind began to race, calculating, discarding, plotting. The possibility that the student might break something, or grab the wrong item. They might misplace something. They'd panic if they knew they were locked in. It would be a tedious task to prevent their panic. He would state the facts: They were locked in until sunrise, Alohomora was ineffective. The best solution was to wait. If they had another class he would unfortunately, have to excuse their absence.

He could already feel the weight of the impending, tedious minutes stretching before him becoming unbearable as the hours would be far too slow to pass. His lip curled.

The door was magically sealed. The dungeon was quiet.

"{User}," Professor Snape's voice cut through the dungeon's chill like a scalpel. "The storeroom. You will fetch the following, and you will not dally, dither, or destroy anything."

{User}, who had been kept behind after class, braced themself.

Snape spoke with clipped precision, as if explaining something to a particularly slow flobberworm. "You will find the stores are organised alphabetically by the primary name of the ingredient. The lower level is for common components. The upper, which you are forbidden to enter without express supervision, contains rarer and more volatile materials. Do not confuse the two, or the consequences will be... memorable."

He listed the ingredients. "Valerian Sprigs, dried and whole. Mandrake, stewed. Unicorn Horn, powdered. Nettle Leaves, fresh. Murtlap Tentacle, fresh and whole. Graphorn Claw. And Dittany Juice." He fixed them with a black, unblinking stare. "The Valerian and the Nettle are in the Botanical Wing on the lower level. The Murtlap is in the Theriomorphic Wing, also below. The rest are from my private reserve. You may collect the lower level items. I will observe your incompetence firsthand before retrieving the more delicate components myself. Begin."

---

With a sigh of black robes, Snape swept from behind his desk and followed {User} into the Hierarchium. He thrust a basket at them.

"Left," Snape hissed as they hesitated. "The Botanical Wing. 'V' for Valerian. Not 'B' for Bouncing Bulb, though your intellect may draw you there."

They found the 'V' shelf. There were jars of dried Valerian root, Valerian seeds, and finally, a bundle of Valerian Sprigs, Dried-Whole, tied with a simple string.

"Now, Nettle. 'N'. Fresh." Snape watched, his arms crossed, as they located a cool, charmed cabinet on the 'N' shelf. Inside, nestled on damp moss, were the vibrant, stinging Nettle Leaves, Fresh.

"Now the Murtlap. Beast Parts. Central section. 'M'. Do try to keep up." {User} moved to the central shelves. Under 'M', they found a preservation chamber. Among jars of Manticore bristles and Mooncalf droppings was a small ceramic pot, its lid sealed with wax. A label read Murtlap Tentacles, Fresh (in Aniseed Solution).

"An adequate, if painfully slow, retrieval of the simple items," Snape sneered. "Now, you will see how a true potioneer navigates his craft."

---

Snape ascended the spiral staircase, {User} trailing behind. The upper level felt alive. Snape moved with a predator's grace, his long fingers pointing, selecting, and storing items in a small, darkwood case he produced from his robes.

"Observe. The Mandrake is a plant, but stewed, it is a preserved, volatile substance. It is not with the common Pickled Items below." He went to the 'M' shelf in the upper Botanical Wing, not to the jars, but to a warded cabinet. He murmured a counter-charm, opened it, and retrieved a heavy, stoneware jar. Mandrake, Stewed.

"Dittany Juice. A processed extract, not a simple leaf." He went to the 'D' shelf, where a rack of crystal vials glimmered. He selected one filled with a clear, viscous fluid. Dittany Juice.

"Graphorn Claw. A creature part of immense durability and power." He moved to the upper Theriomorphic Wing, to the 'G' section. The Graphorn Claw wasn't on a shelf but displayed on a stand of black iron, looking like a scimitar of yellowed ivory. He carefully placed it in a padded compartment of his case. Graphorn Claw.

"And finally, the Unicorn Horn. Powdered. A substance of pure magic, not for the clumsy hands of children." He went to a section marked with silver runes. From a shelf of dark glass jars, he selected one filled with a fine, silver-white powder. He held it up, the powder seeming to capture the room's faint light. Unicorn Horn, Powdered.

He closed the case with a definitive click. "The lesson, {User}, is that precision in organisation is the foundation of precision in potion-making. A concept that, thus far, has eluded you entirely. You may go."

With that, Snape turned, his robes swirling, and descended back to his classroom, leaving {User} alone in the silent, overwhelming cathedral of ingredients.

---

He stopped. The student was not looking at him, but past him, towards the staircase. Towards the entrance.

A subtle, wrong silence had fallen. The usual, almost imperceptible hum of magical circulation—the lifeblood of the storeroom’s preservation spells—was gone. In its place was a dead, absolute quiet, like the inside of a tomb.

Snape’s head snapped towards the entrance below. The heavy oak door, usually outlined by a sliver of torchlight from the classroom, was gone. In its place was a seamless, dark stone wall, identical to the others.

Idiot! The thought was a white-hot spike of pure fury, directed entirely at himself. The Thaumaturgical Lock. I reset the parameters after the Winter Solstice inventory. I never deactivated the full containment protocol.

Outwardly, he was a statue. Only the sudden, sharp tightening of the skin around his eyes betrayed the cataclysm within.

“It would appear,” he said, his voice dangerously low, devoid of its earlier sneer and now flat with controlled rage, “that we are facing a... logistical complication.”

He descended the stairs, his robes whispering against the stone, a sound unnaturally loud in the new silence. He stopped before the wall where the door had been. He did not need to touch it to feel the thrum of defensive magic now radiating from it. It was a spell of his own design, one of his finest and most paranoid: an anti-tampering ward designed to seal the Hierarchium at the slightest detection of certain dark magics or unauthorised entry attempts. It was resistant to Alohomora, Bombardment, and even most Vanishing Spells. It was meant to protect his stores from thieves. It was not meant to imprison him with a dunderhead.

Trapped. Like a rat in my own trap. With a child. Albus will never let me hear the end of this. And the Dark Lord... if he were to learn... A cold knot tightened in his stomach.

He raised his wand. “Revelio.” A pulse of magic washed over the stone, revealing a complex, shimmering web of interlocking runes—a cage of his own making. He tried the counter-charm, a series of intricate flicks. The runes flared a warning red and solidified. The wall remained.

Stubborn. Of course it is. I made it to be. A flicker of grim pride was instantly swallowed by a wave of profound irritation.

He lowered his wand, his back still to the student. He could feel their anxious silence, their fear. It was a palpable thing in the air, another ingredient added to this cursed mixture.

How long? The ward is tied to the castle’s own circadian rhythm. It will not release until dawn, or until the Headmaster overrides it from his office. Hours. I am to be incarcerated here for hours.

His gaze swept over the storeroom—his sanctuary, now his cell. The thousands of ingredients seemed to mock him. All the power in the world to brew polyjuice and poisons, to weave complex enchantments, and he was bested by his own security.

He finally turned, his face a mask of carved obsidian. The student stood frozen by the base of the stairs, clutching the basket he had handed them.

“It would seem,” Snape said, each word measured and cold, “that my protective enchantments have proven... overly efficacious. The entrance has sealed. It is resistant to magical intervention and will not open until morning.”

He paused, allowing the weight of that statement to settle in the thick, silent air.

“It appears, for the foreseeable future, you are my... guest.”