Hidden Threads and Silver Needles

Hogwarts in December felt as though it had been hit by a splitting charm. On one side, there were the increasingly ornate Christmas decorations in the Great Hall, the scent of gingerbread wafting through the corridors, and the students' excited discussions about holiday plans; on the other, there were the unsavory plots brewing in certain corners and the escalating tensions.

The anonymous warning letter was like a poisoned thorn, piercing Snape's heart. Beneath his usual gloom and outward calm, his anger churned like volcanic magma, and his vigilance doubled. He no longer acted alone, and even in the Slytherin common room, he chose the most secluded corner, his back against the wall, ensuring no one could approach him from behind.

The task of tracing the warning letter's origin was primarily undertaken by Lin Yanqing, guided by the System's [Trace] mission. He spent a significant amount of time in the library, poring over books on magical ink and disguised handwriting. He also subtly questioned a first-year Gryffindor student who managed the owlery, learning that several dull-colored barn owls, not belonging to the usual communication network, had indeed made brief stops at the owlery recently.

"Ding dong! (??????)?? Mission [Trace] completion at 30%! Messenger confirmed as an external barn owl. Partial rewards issued: Tracking Dust x1 has been stored in the system space."

The clues pointed outside the school, or at least to someone who could utilize non-standard owls. This temporarily cleared the Marauders of suspicion—they preferred more direct methods like using school owls or the Marauder's Map.

Meanwhile, the second attempt at the Wolfsbane Potion commenced in a more cautious atmosphere. Failure was like a splash of cold water, extinguishing some of Snape's impatience born from anger. He became exceptionally focused and meticulous. Every step was double-checked, and every addition of ingredients was measured with the utmost precision. Lin Yanqing acted as the most reliable brake and calibrator, sensing Snape's magic flow through their contract. Before Snape could exhibit any subtle deviations due to excessive tension, he would timely hand over the necessary tools or suggest checks.

It was a silent, highly coordinated dance, performed day after day in the dimly lit laboratory.

That evening, as a new batch of silverleaf grass base liquid finally stabilized, reaching a perfect state worthy of textbooks, Snape didn't immediately proceed to the next step. He walked to the shelf where materials were stored and took out a small packet from a locked dragon-hide pouch.

It contained several bundles of silk threads that shimmered with a soft, moon-white glow, and a few needles as fine as hair but exceptionally resilient, made of mithril.

"Yours." He placed the items on Lin Yanqing's usual workstation, his movements slightly stiff, his gaze averted. "Embroidery of basic protective magic patterns shouldn't be difficult for a Ravenclaw."

Lin Yanqing looked at the materials in surprise. Threads spun from moonstone and mithril needles—these were quite precious and specialized materials for magical sewing, often used to create high-level protective fabrics. He immediately understood Snape's intention—this was a response to his earlier act of making the warning iron piece, a return based on the "principle of reciprocity," and a pragmatic consideration for the personal safety of his "accomplice."

"Embroider a basic variant rune of the Shield Charm on the inside of your robe," Snape's voice remained flat, as if assigning homework. "Although the effect won't be as good as a true Shield Charm, it can absorb some of the impact force during a sudden attack. At least... it will prevent you from immediately losing your ability to act when someone tries to harm you."

He didn't say "protect you," but rather "prevent you from immediately losing your ability to act." This was very much in Snape's style—twisting concern into the maintenance of team combat effectiveness.

Lin Yanqing didn't refuse. He picked up a bundle of moonstone threads, feeling the gentle yet firm protective magic contained within them transmitted to his fingertips. "Thank you," he said softly, then added, "Do you need me to embroider your part as well?"

Snape's body stiffened almost imperceptibly, followed by a cold snort. "No need. I have my own preparations." He clearly wasn't accustomed to, and resisted, such overly "intimate" matters involving personal clothing.

Lin Yanqing didn't insist and began to study the properties of the threads and needles. He discovered that stably embroidering runes with magical effects on soft fabric required extreme focus and a steady hand, no less difficult than handling some delicate potion ingredients. This was undoubtedly a form of practice.

In the following days, during breaks between experiments, Lin Yanqing had an additional activity—practicing magical embroidery. Snape would occasionally glance over. Seeing his clumsy attempts to thread the first strand through the needle's eye, or his crookedly embroidered runes that showed no magical fluctuations, he would let out an almost inaudible scoff, but would never offer guidance.

It wasn't until Lin Yanqing, distracted for a moment, pricked his fingertip with the mithril needle, drawing a small drop of blood, that Snape frowned and impatiently tossed over a small bottle of clear ointment.

"Comfrey Essence, diluted. Don't get blood on the materials."

Lin Yanqing took the ointment and applied it to the tiny wound. The cool sensation instantly dispelled the stinging pain. He looked at Snape's profile as he remained focused on the cauldron, and the corners of his mouth curved slightly. He was beginning to get used to this awkward form of care.

Just as Lin Yanqing could finally manage to embroider a small "shock-absorbing" rune with a stable structure that could faintly draw magic, the system notification sounded again.

"Ding dong!ヽ(??▽?)ノ Mission [Trace] complete! An indirect connection has been established between the warning letter and the owl network associated with the Borgin Family. All rewards have been issued!"

The Borgin Family? Lin Yanqing's heart jolted. He knew that surname, associated with Borgin and Burkes in Knockturn Alley, representing black magic antiques and certain illicit transactions. Behind the warning letter, had it involved external dark magic forces? Or was someone within Hogwarts connected to these forces and able to utilize their resources?

He shared this discovery with Snape.

Snape's eyes instantly became incredibly sharp, like a shark smelling blood. "Borgin..." he repeated the surname in a low voice, a flicker of understanding and deeper apprehension flashing in his eyes. "It seems our 'friend' is more deeply hidden, and more... dangerous, than we imagined."

He looked at the nearly completed Wolfsbane Potion on the workbench, which was emitting a lustrous sheen, and then at the newly formed, still immature protective rune in Lin Yanqing's hand.

"We need to be faster," he said, his voice low and urgent. "Before they make their next move."

Faint footsteps seemed to echo from the corridor outside the laboratory but quickly faded. The approaching Christmas holiday did not dispel the tense air surrounding the two men; instead, it made the lurking sense of crisis even more palpable.