London's finest future double agent, legendary Potions Master, future Headmaster, and universally renowned sharp-tongued terror—Severus Snape. Just what kind of clandestine potion project was he secretly brewing up?
Regulus had a strong, instinctual feeling that it had something to do with his brother's little gang of troublemakers.
Rumor had it that during a Potions class last month, James Potter's cauldron had violently erupted, spewing a foul-smelling, thick green smoke that instantly ruined the delicately balanced potions of an entire row of students. Professor Slughorn's face had literally turned green from the fumes, and Gryffindor had inevitably lost a massive chunk of points.
Sirius had loudly and aggressively accused Snape of secretly tossing a porcupine quill into James's cauldron when no one was looking. However, without a shred of concrete evidence, Sirius's accusations only earned him a barrage of unreserved, lethal mockery from the Slytherin boy.
It was an eye for an eye. In retaliation, during the very next Transfiguration class, James had sneakily injected a massive dose of high-grade itching powder directly into Snape's practice materials. The result was catastrophic: Snape's face and scalp broke out in violently red, unbearable hives. The powder had unfortunately affected a few innocent bystanders as well, but it successfully forced Snape to flee the classroom to frantically scrub his hair, allowing the Gryffindors to barely scrape back a win for the round.
This guy, Potter, was practically a menace. He had grown up in Godric's Hollow, a village with a heavily aging wizarding population. From the moment he could walk, he had been doted on and protected by a legion of elderly witches and middle-aged wizards, allowing him to endlessly practice magic and cause absolute havoc without real consequence. His practical skills were undeniably top-tier.
As for Severus Snape? He was a lone wolf who frequently relied on incredibly risky moves, sheer ruthlessness, and wildly unexpected tactics. He was currently fighting a brutal, back-and-forth guerilla war against Potter, Black, and Lupin entirely by himself.
Regulus deeply admired the sheer grit of it. When your opponents heavily outnumber you, possess infinitely better family backgrounds, and have raw talent that easily matches your own... you have to put in double the effort and fight twice as dirty just to survive.
The burning desire to prove oneself, the desperate, clawing need to win—it seemed to be an incredibly powerful driving force for the young Slytherin.
Not to mention, there was also the highly volatile factor of a certain red-haired Gryffindor girl mixed into the feud.
Now, the ball was back in Snape's court. What kind of nasty surprise was he preparing to unleash?
As for Regulus himself, he was currently suffering through the agonizing reality of school detention. And this was with Professor Slughorn actively being lenient!
As a student, his daily schedule was already brutal. He had to haul himself to different classrooms across the massive castle every single day, practically live in the library to keep up with the reading, constantly practice complex wand movements, and somehow survive the crushing mountain of homework and final exam revisions. On top of all that, he was now locked in a dungeon every night from six o'clock onward!
Detention made him incredibly, desperately nostalgic for the absolute freedom he'd enjoyed just a week ago. It felt exactly like being in prison. Detention wasn't just a punishment of manual labor; it was a punishment of time, which was the very essence of life itself.
Regulus actually started to deeply admire Sirius and his friends. How on earth do they have so much free time to cause this much trouble?! He, too, wanted to be full of boundless energy after a grueling day of classes. He wanted to party late into the night, secretly wander the terrifying depths of the Forbidden Forest without a second thought for sleep, and cause legendary chaos. But the tragic reality was... he was just really, really sleepy by 9 PM!
Thinking about the fact that he still had to finish his Transfiguration essay and then secretly explore the castle after his detention finally ended tonight, Regulus genuinely wanted to leave his 'Golden Finger' cheat system a scathing one-star review.
Time-Turner urgently needed! On Friday night, during his penultimate detention session, Regulus casually slid a piece of Honeydukes chocolate across the workbench toward Severus.
Severus originally stiffened, absolutely refusing to accept anything freely given by a Black. But his resolve crumbled when Regulus smoothly poured him a steaming cup of tea and casually pointed to the delicate sugar lily decorating the center of the chocolate square.
"It's lily-flavored," Regulus said softly, not looking up from his chopping board. "It's quite rare. Thought you might appreciate it."
Once was a novelty; twice established a habit.
Severus had to admit, albeit entirely to himself, that his initial opinion of the younger Black had drastically changed over the course of the week. This Regulus was shockingly silent, incredibly steady, and completely, fundamentally different from the loud, arrogant, insufferable Black polluting Gryffindor House.
What truly hit the fiercely proud, deeply insecure little Severus right in the heart was Regulus's quiet respect. The younger boy frequently wore expressions of genuine awe when observing Snape's flawless knife techniques or deep theoretical knowledge. Furthermore, Regulus's casually friendly gestures—sharing high-end snacks, remembering how he took his tea, never talking down to him—slowly chipped away at Snape's icy exterior.
What an unusually perceptive young man, Snape thought. He was hardworking, possessed impeccable pureblood manners, and treated Severus as an absolute equal, if not a superior. It was strangely... comfortable to work alongside him.
At the same time, Snape found himself deeply fascinated by Regulus's utterly bizarre approach to ingredient preparation. The boy subjected innocent potion ingredients to all sorts of horrific, unconventional torture—crushing, burning, freezing, and mashing them—and then meticulously recorded the volatile effects in a leather-bound journal.
For Regulus, the logic was simple: now that he finally had access to high-grade experimental materials fully paid for by public school funds, he absolutely had to test every possible variable to strive for maximum efficiency.
Finishing his final batch of chopped roots for the evening, Regulus shot Severus a knowing look. Capitalizing on Professor Slughorn's temporary absence from the office, Regulus pulled out a roll of parchment and began writing like lightning, desperately trying to knock out his Charms homework.
Beside him, Severus was carefully brewing a complex, bubbling potion designed to drastically sharpen mental focus—a Wit-Sharpening Potion, or 'Wakefulness Potion.' It was easily the most highly sought-after contraband in the castle during the brutal exam revision period. Slughorn frequently used vials of the stuff as rewards to artificially inflate his students' enthusiasm for his 'Slug Club' meetings.
"I'm heading out now, Severus," Regulus whispered, hastily rolling up his finished essay. "See you!"
The next day was finally the weekend, meaning he could thankfully sleep in. Because of this glorious fact, Regulus planned a massive, highly dangerous project for late Saturday night.
He moved through the castle with extreme caution, sticking to the deepest shadows. He occasionally had to freeze behind statues to avoid the prefects wandering the corridors late at night, and he frequently had to stop to silently bribe the glowing-eyed cats roaming the castle with bits of dried fish. Some of these felines were Argus Filch's personal informants, and he had quickly learned the hard way that his 'Stealth' state was currently completely ineffective against the heightened senses of animals.
Thinking about Potter's legendary Invisibility Cloak... now THAT is a real cheat code! Regulus sighed heavily as he finally slipped into the infamous, perpetually flooded girls' bathroom located on the second floor of the castle.
He pushed open the heavy wooden door bearing the large, rusted sign that read: OUT OF ORDER.
This was the very first time he had visited this specific location since transmigrating to Hogwarts. The air was thick with damp mildew. The sinks were chipped and covered in grime, the mirrors were cracked, and the floor was permanently slick with a layer of foul-smelling water. (Further environmental description omitted for the sake of sanity—in short, it perfectly set the horrific, deeply gloomy atmosphere required for a future Basilisk attack). "You're not a girl!"
A translucent, pearly-white face suddenly popped upside down right through the wooden door of the innermost stall. She wore an exaggerated, deeply melancholic expression, had lank, straight hair, and wore a pair of thick, pearly glasses.
"Obviously," Regulus replied smoothly, unfazed. Unexpectedly running into the resident ghost the exact second he arrived, Regulus offered a polite, formal nod. "Good evening, Moaning Myrtle."
"You... you know Moaning Myrtle?!" The ghost floated fully out of the stall, hovering a few inches above the wet floor. She scrutinized him with highly suspicious, narrowed eyes. "Wait a minute. You look incredibly familiar!"
"Have you, by any chance, seen my older brother around? His name is Sirius Black."
"Sirius Black..." Myrtle repeated, her voice taking on a sudden, breathy, operatic tone. A surprisingly shy, girlish expression crossed her translucent features. "Oh! So you're the brother of that incredibly handsome boy with the lovely dark hair! But..." She floated closer, inspecting his face critically. "...you're definitely not quite as handsome as he is!"
"Yes. I am aware," Regulus nodded stiffly, suddenly completely at a loss for words. He mentally cursed his social skills. He clearly wasn't very good at talking to girls—and he was apparently even worse at talking to dead ones.
"Well, what are you doing in my bathroom? You're not here to laugh at poor, miserable Moaning Myrtle, are you?!" she suddenly shrieked, instantly spiraling into a victim complex. She started talking frantically to herself, wringing her pearly hands. "They always come to laugh at me! To throw things at me!"
"No, I assure you—"
"Nobody cares about Moaning Myrtle! I have feelings too, you know!" Massive, shimmering ghost-tears inexplicably welled up behind her thick glasses. With a dramatic, watery wail, she spun around and dove headfirst back into the toilet bowl of her stall. A massive, echoing splash of water erupted over the door.
Regulus slowly shook his head, wiping a drop of toilet water from his cheek. He hadn't even had time to ask her a single question about the plumbing! This 'creature' called a female ghost was simply too emotionally volatile to deal with tonight.
Just as he turned back to the sinks to begin meticulously checking the copper taps one by one for the etched snake emblem, the sharp, distinct sound of footsteps echoed from the stone corridor outside.
Regulus reacted instantly. He reached behind him, ripped open the door of a small, cramped stall, and practically threw himself inside. He locked it silently and carefully stepped up onto the porcelain toilet lid, balancing his weight perfectly so his boots wouldn't be visible from beneath the gap.
The heavy wooden door of the bathroom creaked open with an agonizing whine. The footsteps moved closer, squelching slightly on the wet floor. The door of the stall immediately adjacent to Regulus's was violently pulled open. The distinct, clinking sound of ceramic vials and heavy metal scales colliding rang out clearly in the quiet bathroom. A few seconds later, the sharp crack of magical fire igniting echoed off the tiles, followed closely by the thick, bubbling sound of liquid being methodically stirred.
Regulus stood frozen on the toilet lid, utterly dumbfounded. This isn't an abandoned bathroom at all! This is clearly the unofficial Hogwarts Potions Club Extracurricular Activity Room! A soft, raspy cough echoed from inside the adjacent stall.
My goodness. Regulus aggressively massaged his temples, suppressing a groan. He would recognize that distinctly gloomy, congested cough anywhere. It was Severus.
After a brief moment of intense internal debate, Regulus cleared his own throat, offering a light, very deliberate cough of his own.
The clanking sounds from the next stall ceased instantly. Dead silence fell over the bathroom.
Regulus pushed open the door of his cramped stall, stepping down and walking casually over to the closed door of Severus's makeshift laboratory. He knocked lightly on the wood.
"It's just me, Severus."
For several agonizing seconds, nothing happened. Finally, the latch clicked, and Severus slowly pushed the door open just a crack. He positioned his body to completely block the bubbling cauldron behind him, staring out at Regulus with absolute, terrifying vigilance. His dark eyes were wide with paranoia, clearly rapidly calculating exactly how Regulus had tracked him here and what his motives were.
"I came here specifically looking for Moaning Myrtle," Regulus said plainly, holding his hands up in a placating gesture. "I was actually here first."
Severus's eyes flickered, analyzing the younger boy's calm expression. Slowly, the intense, murderous tension in his shoulders softened considerably.
"What possible business could you have with Moaning Myrtle?" Snape sneered softly, though the venom lacked its usual bite.
"Can you keep a massive secret?" Regulus countered, tilting his head thoughtfully.
"Of course I can," Severus replied immediately, his chin lifting defensively. "Can you?"
Behind Snape's legs, the hidden cauldron suddenly made a loud, violent POP! Regulus watched in amusement as Severus visibly forced his neck muscles to lock, refusing to turn around and check on his highly illegal contraband while his enemy's brother was watching.
"Of course. Slytherins never tell tales outside the House," Regulus swore solemnly. He pointed a casual finger past Snape's shoulder at the flickering magical candle. "Besides... I consider us friends. You really should look at your potion before it melts the floorboards."
Upon hearing the word "friends," a deeply complicated, incredibly strange expression twisted across Snape's sallow face. But the immediate threat of a cauldron explosion won out. He let out a harsh sigh of relief, quickly turning his back on Regulus to frantically stir the violently bubbling concoction.
The potion emitted a surprisingly clean, sharp, minty scent that completely overpowered the moldy stench of the bathroom. Even with Regulus's recently accelerated potions knowledge, he couldn't place exactly what complex poison or prank the Half-Blood Prince was brewing.
"Tell me, Severus," Regulus began, leaning casually against the stall frame as he watched the older boy work. "Have you ever heard the ancient legends regarding the four original founders of Hogwarts?" He kept his tone incredibly light and conversational. "I accidentally overheard Sirius boasting to Potter. He claims he wants to find the 'Lost Treasure of Hogwarts.'"
At the absolute hated name of "Sirius," Severus's spine stiffened, and his ears visibly perked up under his greasy hair.
To make the bait utterly irresistible, Regulus smoothly began weaving in highly convincing, completely unverifiable family lore. "You see, our great-great-grandfather, Phineas Nigellus Black, was once the Headmaster of Hogwarts. We actually have his magical portrait hanging in the main drawing room at Grimmauld Place, exactly like the one up in the Headmaster's office."
Severus paused his stirring. He had indeed read in Hogwarts: A History that the Most Noble House of Black had once produced a deeply unpopular Headmaster.
"Well," Regulus continued, lowering his voice conspiratorially. "Great-great-grandfather Phineas once let slip to my father that the legends of a massive, hidden Founder's treasure... are actually documented in the restricted archives."
"So..." Severus turned slowly, his black eyes gleaming in the candlelight. "You are sneaking around an abandoned girls' bathroom at midnight... to collect clues?" He deliberately emphasized the absurdity of the location.
"Exactly," Regulus nodded seriously, stepping fully into the stall. "So here is my proposition: if you tell me exactly what it is you're brewing... I will tell you exactly what clues I've found so far."
Snape's eyes widened in genuine shock. "You... you already have concrete clues?"
Take a wild guess, Regulus thought, a brilliant, thoroughly mysterious smile spreading across his face.