After first-year Harry Potter received the Invisibility Cloak—a gift from Dumbledore left by his father—a constant impulse lingered in his mind.
Donning the Invisibility Cloak meant that Hogwarts Castle was open to him; he could go anywhere he wished. He wouldn't be caught by Filch, nor seen by any Professor.
He could even use the Invisibility Cloak to check the Restricted Section of the Hogwarts Library to find out who Nicolas Flamel was and understand what that annoying Snape was looking for behind the trapdoor.
However, he had a thought he told no one: he wanted to be alone the first time he used the Invisibility Cloak, because it was something his father had left for him.
Harry thought this, then took action when night fell.
Passing through the common room archway cloaked in the Invisibility Cloak, walking past the moving staircase and long corridors, he slipped into the Hogwarts Library entrance; everything went surprisingly smoothly.
Until he encountered someone in the Restricted Section—Professor Greengrass.
Fortunately, the bookshelves concealed him, preventing him from startling the other person.
Professor Greengrass appeared to be reading very intently. Harry quietly hid his lamp under the Invisibility Cloak, then tiptoed past him from behind.
He didn't check what book Professor Greengrass was reading; the Restricted Section was vast anyway. He just needed to secretly take a book back to his dormitory and return it tomorrow night.
He moved through the bookshelves, completely unnoticed by the Professor. Harry was very pleased with his Invisibility Cloak, which made him even more curious about his father.
What kind of person was he?
Why did he possess such a magical Invisibility Cloak?
Had he done the same when he was a student at Hogwarts—roaming the castle at night cloaked in the Invisibility Cloak?
A series of questions flooded his mind. Harry absentmindedly walked between the bookshelves, then he seemed to hear a sound—a voice calling to him.
He stopped in front of a row of bookshelves, reached out, and took down a thick book from the shelf.
The Book of Answers—it read on the cover.
The faint call grew stronger, as if telling him that if he opened this book, all his doubts would be answered within, just as its title promised.
Normally, Harry would have refused without hesitation, because Ron had told him many times that books of unknown origin were very dangerous.
But at that moment, he was completely captivated by the book, so much so that he opened the flyleaf without hesitation.
A piercing scream suddenly erupted from the book.
On the book's cover, a grotesque face seemed to struggle to squeeze out, and the scream came from its mouth.
Harry was startled by the sudden change. He slammed the book shut and frantically shoved it back into place.
The screaming stopped; everything that had just happened felt like an illusion—but his reason reminded him it was all real.
Because he could hear footsteps approaching—and more than one...
Harry pulled on the Invisibility Cloak and stood up abruptly, knocking over his lamp in his panic, but he couldn't worry about that now. The footsteps were getting closer. If he were caught, how many points would Gryffindor lose?
He ran out of the Restricted Section without looking back, narrowly avoiding Filch and his cat at the Hogwarts Library entrance, slipping past their wide-eyed stares and rushing into the darkness.
After running blindly for a while, Harry felt he had gone far enough, so he stopped to catch his breath.
"Professor, you said to inform you if I found anyone wandering around the school or trespassing in the Restricted Section."
Harry was startled by Filch's sudden voice and almost cried out.
"Restricted Section? Who is it? Did you see him?" Snape's voice followed, and Harry became even more terrified.
"It's me!" Sagres emerged from the darkness.
He held a book in his left hand, and a faint cry still emanated from its flyleaf.
"Sagres, it's you again…" Snape spat his name through gritted teeth. "What do you think you're doing?"
"Doing what I do every day," Sagres replied expressionlessly. "Aren't you two lovers still up to the same old tricks as years ago?~"
After speaking, he walked over to Filch and thrust the book he was holding into his arms.
The action startled Filch, making him involuntarily take a step back.
"The Book of Answers—a standard Dark Arts text, detailing the damage caused by various Dark spells…" Sagres looked faintly into the darkness, then pointed at the book in Filch's arms. His expression was cold, and his tone stiff: "Can't I read it? Or do I need to report to you?"
"No… no need, Professor…" Filch strained his neck back as far as possible, as if trying to get away from the book.
"He's just trying to do his job," Snape said, reaching out to take the book from Filch's arms.
"Oh? Are insults and corporal punishment of students part of the job as well?" Sagres looked at Snape with a half-smile. "As expected of your partner; after all, protecting Slytherin students is part of your job too."
Without waiting for a response, and ignoring Snape's grim expression, he took the book directly from his hand and walked into the darkness without looking back.
He hadn't entirely meant to pick a fight with the two of them; rather, he had discovered something more interesting.
From the moment he had begun reading in the Restricted Section, he had noticed a Young Wizard illegally roaming there at night.
Moreover, the student used a very rare item—an Invisibility Cloak—A powerful one.
Such an item was not common among Hogwarts students, and Sagres had seen ordinary Invisibility Cloaks before—they were vastly different from this one.
If not for the faint footsteps that betrayed the intruder's position, he wouldn't even have noticed someone hovering in front of him under an Invisibility Cloak.
This indicated it was a magical item of exceptionally high quality. If he'd had this when he was a student, neither Snape nor Filch would have seen so much as a strand of his hair.
He had just sensed that the person had hidden in an abandoned classroom not far from where they had been speaking, so he planned to return and check once Snape and Filch were gone. However, Sagres estimated that the other person was a Young Wizard—after all, a Professor could access the Restricted Section freely and had no need for an Invisibility Cloak.
As the light from Snape and Filch gradually disappeared, Sagres quietly returned to the door.
He cast a Disillusionment Charm on himself, then entered the classroom.
It was Harry Potter, who now stood in front of a massive mirror, his expression complex.
Sagres glanced at the inscription across the top of the mirror and immediately recognized it as the Mirror of Erised, also known as the Mirror of Desire.
Those who stand before it can see their deepest desires reflected within, and countless people have become lost in its allure.
Sagres pursed his lips, thinking this must be another one of Dumbledore's tricks. Otherwise, how could such a magical item be placed here so casually?
Not even the door was locked—could it be any more obvious?
With that thought, he looked around but found no one else present.
Shaking his head, he concluded that Dumbledore was likely giving the boy a test—to train Harry.
So Sagres no longer paid attention to the Young Wizard standing before the mirror and quietly left this "trap" meticulously set by Dumbledore.