Owl's Warning and the Changing Potions

The second week of December saw Hogwarts enveloped in festive busyness. Students discussed their Christmas holiday plans, and the corridors carried the scent of gingerbread and roasted chestnuts. But beneath the cheerful bustle, discordant undercurrents stirred in certain corners.

Transfiguration Class had just ended, and students were filing out. Lin Yanqing was packing his books when he felt a gentle tug on his sleeve. He looked up to see Snape standing at the classroom door, giving him a swift, significant glance over his shoulder – a signal to go to the Room of Requirement.

When Lin Yanqing arrived, he found Snape standing by the workbench, his expression even more somber than usual. He held a crumpled piece of parchment in his hand, written in a shaky, clearly disguised script:

"Curiosity killed the cat, especially on a full moon night. Some people had better learn to mind their own business, or next time, it won't just be a tuft of fur they lose."

There was no signature, no seal, just like a corner torn haphazardly from an old book.

"It appeared in my Potions textbook this morning," Snape's voice was icy as he tossed the note onto the counter. "Within the few minutes I left my seat to submit my essay."

Lin Yanqing picked up the note and examined it closely. This wasn't the Marauders' style; they preferred direct humiliation or pranks, not this sinister warning. This felt more like... a genuine threat.

"You think it's the person from outside the door that night?" Lin Yanqing asked.

"Obviously," Snape's fingertips tapped restlessly on the counter, betraying his unease. "They know more than we think. Full moon night, eyes... " he gave a cold laugh, "They're warning me not to investigate Lupin further."

[System Notification! Detected explicit threat towards Contract Target!
Triggering Crisis Response Mission - [Trace]!]

Mission Description: The appearance of an anonymous warning letter signifies that hostility has surfaced! Identify the source or sender of the letter.

Mission Requirements: Determine the approximate source or sender of the warning letter within 48 hours.

Mission Reward: Tracking Dust (can attach to messenger or contact, providing short-term location clues) x1, System Points +80.

Failure Penalty: Probability of Contract Target encountering prank-level harassment increases by 50%. (▼へ▼メ)]

"We need to find out who it is," Lin Yanqing put down the note and looked at Snape. "The handwriting is disguised, but the delivery method is a clue. Slipping it into your textbook without you noticing..."

"Means they were likely in that classroom, or had an accomplice," Snape finished, a flash of ferocity in his eyes. "Someone watching me, who doesn't want me digging into the werewolf secret."

This realization made the atmosphere in the lab even more oppressive. The enemy was no longer hiding in the mist; they had become tangible, malicious tendrils reaching out to them.

However, misfortune rarely comes alone.

That evening, as they continued refining the Wolfsbane Potion, an accident occurred. Just as Snape was about to pour the prepared "Moonlight Moss extract" into the main cauldron for the crucial fusion with the Silverleaf Grass base, Lin Yanqing, through their contract, suddenly felt a minuscule, fleeting hesitation in Snape's flow of magic – perhaps due to the strain of consecutive days of mental tension and the sudden warning letter causing him to lose focus.

It was this almost imperceptible slip that caused the extract to drip a fraction of a second too quickly.

"Ssssss--"

The steady, emerald-green potion swirling in the cauldron suddenly churned violently. Its color instantly turned murky, emitting a bitter, scorched smell. An unstable magical fluctuation overflowed from the cauldron.

"Back off!" Snape roared, his wand moving swiftly as he tried to stabilize the potion. Lin Yanqing also moved forward immediately, ready to cast a stabilizing charm.

But it was too late. With a dull thud, the potion in the cauldron completely lost its balance, turning into a glob of viscous, bubbling dark brown residue, its potency utterly destroyed.

Nearly two weeks of effort, on the verge of seeing initial results, had gone to waste.

A deathly silence fell over the lab. Only the failed potion at the bottom of the cauldron emitted a faint, mocking "glug."

Snape stood frozen, unmoving. The knuckles of his wand-wielding hand were white from exertion, the veins on the back of his hand bulging slightly. Lin Yanqing could feel through their contract the overwhelming emotions of frustration, anger, and self-loathing that threatened to consume him. He stared fixedly at the residue, a storm brewing in his dark eyes.

This wasn't just a failed experiment. It was a naked proof of insufficient strength when external threats loomed. It was a heavy blow in the field he was most proud of, caused by his own mistake.

Lin Yanqing didn't offer any words of comfort. He knew any words would be hollow at this moment. He silently walked forward, began cleaning the messy workbench, moved the discarded cauldron aside, and prepared new equipment.

After a long while, so long that Lin Yanqing thought Snape might remain petrified, he heard an extremely faint sound, almost squeezed through gritted teeth:

"...It was my mistake."

This wasn't an apology, but an acknowledgment of his own incompetence, a hatred for his own failings.

Lin Yanqing stopped what he was doing and looked at him. Snape still hadn't turned his head, but the taut line of his jaw showed he was struggling to control his emotions.

"We still have the ingredients," Lin Yanqing stated the facts calmly, his voice devoid of accusation or pity, as natural as saying "tomorrow will be sunny." "We can start over. Besides, we've learned that when adding the Moonlight Moss extract, we need a slower speed and more stable magic output than anticipated. This failure has prevented a potential collapse in a more critical step in the future."

He defined this failure as a "valuable data point."

Snape suddenly turned to look at him, a hint of disbelief in his eyes. He had expected to see disappointment, or worse, pity. But in Lin Yanqing's eyes, he saw only pure calm and an analysis of the facts.

The self-loathing that had threatened to crush him was strangely lessened by those words. The failure was no longer pure shame, but experience that could be analyzed and utilized.

He took a deep breath and slowly exhaled. The burning anger in his chest gradually subsided, transforming into a deeper, colder resolve. He no longer looked at the failed cauldron and turned towards the shelf where the ingredients were stored.

"Let's start again," he said hoarsely, his tone returning to its usual sternness, but with a newfound depth. "Next time, we won't fail."

Outside the window, the night was deep. Somewhere in the castle, the enemy who sent the warning letter lay hidden. Inside the lab, the shadow of failure had not yet completely dissipated. But the two young men, one cleaning up the debris, the other preparing new materials, silently reached a consensus—

Threats would not make them retreat, and failure would not break them.

The real contest had only just begun.