Click.
With a heavy sound, the oak door with the griffin knocker slowly opened.
William, carrying his suitcase, walked down the spiral staircase. As soon as he turned the corner, he found two people standing in the corridor.
They were conversing in low voices, seemingly waiting for something—the diminutive Professor Flitwick and the stern-faced Professor McGonagall.
"Oh, it seems our new colleague is out." Professor McGonagall adjusted her glasses, looking at William as he descended. "The moment you entered the Headmaster's office, Filius hurried over to ask me if you had arrived."
William immediately quickened his pace, approaching the wizard who only reached a normal person's waist.
Without any airs, he squatted down naturally and gave the other man a warm and enthusiastic hug.
"Long time no see, Professor Flitwick."
As the Head of Ravenclaw House, Professor Flitwick had always considered William one of the prized students of his teaching career. Seeing his former student return, the professor, who had goblin ancestry, flushed with joy and laughed in a high-pitched voice.
"Haha, Minerva was right. It truly has been a long time, William."
After releasing the embrace, Flitwick continued to survey William with a beaming smile, exclaiming, "I must say, your performance in the '83 All-England Wizarding Dueling Competition was simply magnificent."
"A champion in his twenties—that is almost unprecedented in history. It's just a pity I had some matters to attend to at the time and couldn't watch it live."
"That was just good luck, Professor," William said with a humble smile. "The war had only been over for a few years, and many true experts didn't participate. If we're talking about real prestige, your championship back in your youth is far more convincing."
These words delighted Flitwick so much that his eyes crinkled into crescents, and even his mustache seemed to curl upwards.
The three exchanged pleasantries in the corridor for a while longer before William suddenly changed the subject. "By the way, could you tell me where Mr. Filch's office is? I need to see him about something."
"Looking for Argus?"
Both Professor McGonagall and Professor Flitwick were taken aback, clearly surprised. Usually, new professors would visit the staff room or tour the Great Hall first. Who went looking for the caretaker immediately upon arrival?
"William just showed me some very interesting little inventions."
At that moment, Dumbledore's voice came from the top of the spiral staircase. He walked down briskly, his blue eyes twinkling.
"I believe these things can help us solve some age-old problems regarding school rules. Of course, it also makes me all the more convinced that inviting William to be the Alchemy professor was a wise choice."
McGonagall and Flitwick exchanged a glance, seeing curiosity in each other's eyes.
Moments later, on the first floor of the castle.
In the dim caretaker's office, Argus Filch sat on a battered wooden chair.
Holding a stack of yellowed disciplinary records, he stroked the scrawny cat on his desk while muttering in a raspy voice, "...setting off Dungbombs in the corridor, detention for a week... I have a feeling, Mrs. Norris, this year's new students will be another bunch of nasty brats..."
Just then, the office door was suddenly pushed open.
Filch whipped his head around, his rheumy eyes glaring at the entrance. However, when he saw the handsome, upright wizard leading the way in, the words he had prepared caught in his throat.
Intuition told Filch he knew this person. This face brought back some unpleasant memories, but this person shouldn't be appearing before him at this time.
Filch pointed a withered finger hesitantly at William. "William... Shafiq?"
"Your memory is excellent, Mr. Filch." William stepped into the office with a smile, showing no disdain for the faint smell of fried fish permeating the room. "However, starting today, I think it would be better if you called me Professor Shafiq."
"Pro... Professor?" Filch was dumbfounded, his eyes nearly popping out of his head.
"That's right, Argus," Dumbledore, following behind, explained with a smile. "William is the newly appointed Alchemy professor this year, and he is concurrently the Defense Against the Dark Arts professor."
"He came here specifically to bring you some alchemical items, hoping to help you enforce school rules more effectively."
Upon hearing "enforce school rules," color instantly returned to Filch's ashen face.
The group followed William back out into the corridor. Under everyone's gaze, William raised his left hand and gently rubbed an ancient-looking silver ring on his index finger.
With a flash of light, a finely carved stone bust appeared in his hand out of thin air.
"Undetectable Extension Charm... and fixed on such a small object?" Professor McGonagall's eyes lit up. "Is this an alchemical ring for storage? That is not common in the wizarding world."
"It did take me some effort," William replied casually, then waved his wand.
The stone bust instantly seemed to come alive, flying to the highest point of the corridor walls on both sides. With a faint click, the base of the statue merged perfectly with the wall, looking just like the castle's original decorations, completely harmonious within the ancient architecture.
Immediately after, William took a heavy book from the silver ring. Complex alchemical patterns flowed across the cover; clearly, this was no ordinary book.
William opened it and showed it to everyone. The first page was not text, but a clear, moving image.
It was the very scene happening right now: the group surrounding William in the corridor. As the real people looked up curiously at the stone statue, the figures in the image looked up in sync.
"Merlin's beard..." Professor Flitwick stood on tiptoe to look at the page, muttering to himself. "Although magical portraits can also serve a surveillance purpose, but... oh, this is clearly much clearer, and the angle is more comprehensive."
"Portraits have their own thoughts, Professor Flitwick," William took over with a smile, explaining. "They visit each other, sleep, drink, and might even lie to cover for students from their own houses."
"And they usually only report to the Headmaster when something major happens. They tend to turn a blind eye to 'minor matters' like wandering at night or casting spells in the corridors."
At this point, William looked at the excited Filch.
"But these alchemical statues are different. They have no feelings, need no rest, cannot be bribed, and will loyally carry out their surveillance mission twenty-four hours a day without interruption."
"So from today on, Mr. Filch, you won't need to run around the castle with a lantern trying to catch people. This single book is enough for you to sit in your office, drinking tea while checking the movements of all young wizards in the corridors. Once you spot a violation, you can strike with precision."
Filch stared at the book in William's hand as if it were a rare treasure. His eyes shone with a fanatical light, seemingly already envisioning the wonderful scene of countless young wizards being dragged into detention by him.
"But, Professor Shafiq..." Although Professor McGonagall was also impressed by the invention, she quickly raised a practical issue. "Hogwarts Castle is so large, with crisscrossing corridors. If we don't rely on portraits and solely use these stone statues to lay a network... the number required must be enormous, surely?"
"There is absolutely no need to worry about that."
William smiled confidently, then motioned for everyone to step back two paces. He raised his left hand again and gently rubbed the silver ring.
Crash—!
Accompanied by a sound like a landslide, countless gray shadows poured out of the ring.
In just a few seconds, a small mountain of alchemical stone statues appeared out of thin air before them, directly blocking half the corridor and nearly burying the diminutive Professor Flitwick.
Facing the dumbfounded, open-mouthed group, William dusted off his hands, turned to the already stupefied Filch, and maintained his smiling demeanor:
"Mr. Filch, you can start working now. I'll have to trouble you to hang a stone statue every twenty meters along all the corridors in the castle. As for those blind spots and corners, you can hang an extra one to ensure there are no dead zones."
"Oh, right, just hang them in public areas like corridors and staircases. Be careful not to have a view into bathrooms, inside student dormitories, or places like that, otherwise, the young wizards will protest if they find out."
William thought for a moment and added that last sentence.