The shift in atmosphere within Hogwarts was palpable. If Sebastian's breakfast lecture had sown the seeds of curiosity, the news that he was formally mobilizing the Auror Training Class to solve the "Mystery of the Chamber" was the water that made it grow into a full-blown obsession.
To the younger students, the Auror Training Class was a group of elite, formidable seniors who stood just one step below the professors themselves. To the members of the class, however, this was the moment they had been waiting for. This wasn't just another practice duel or a lecture on the theory of counter-curses; this was a live investigation into a millennium-old legend.
When Sebastian entered the designated training hall on the fifth floor, the air was humming with an intensity that usually only preceded the N.E.W.T. exams. Cedric Diggory was checking the tip of his wand, his face set in a mask of professional focus. Nearby, a group of sixth-year Gryffindors were debating the properties of petrification.
"Professor!" a seventh-year Ravenclaw called out the moment Sebastian crossed the threshold. "We're ready. Tell us where to start. Do we sweep the dungeons? Should we be setting up detection wards around the third-floor corridor?"
Sebastian raised a hand, a slight, knowing smile on his face. "Patience is the first weapon in an Auror's holster. If you rush into a dark room without a light, you're just giving the enemy a free target. Before we cast a single spell, we need to use the most powerful tool we have: logic."
He stood at the front of the room, his eyes scanning the thirty or so students. "To solve any crime, you look for the anomaly. Something that doesn't fit the pattern of the environment. Now, let's look at our crime scene. Harry Potter and his companions were found at the site. Why?"
The room went silent. All eyes turned toward Harry, who was sitting near the back, looking like he wanted to vanish into the stone floor. Being the "Boy Who Lived" was one thing, but being the "Boy Who Hears Murderous Voices" was a much lonelier title.
"A suspect list usually starts with the first person at the scene," Sebastian continued. "But the Professors have already cleared Mr. Potter. So, let's look past him. What was the biggest anomaly about last night?"
"The feast!" Cedric Diggory spoke up, his eyes bright with a sudden realization. "Professor, almost every living soul in this castle was in the Great Hall. The ghosts were at their own party. If the culprit wanted to move through the halls unseen, Halloween was the only night where they could guarantee the corridors would be empty."
"Excellent, Cedric," Sebastian said. "An Auror looks at the schedule. If everyone is in Point A, the criminal is at Point B. But even Point B has its own rules. To leave that message and hang a cat, you need time. You need to be sure you won't be interrupted by a student going to the bathroom or a prefect doing an early patrol."
He tapped a parchment on his desk, and a list of names appeared in glowing ink. "Your first task isn't to hunt a monster. It's to hunt for absences. An elite Auror is, at their core, a master of information gathering. You need to become the eyes and ears of the castle."
The students leaned in, sensing the shift from theory to action.
"I want you to divide into teams," Sebastian instructed. "I want you to interview your housemates. But—and this is critical—you are not to interrogate them like criminals. If you act like the secret police, people will lie to you just because they're annoyed. You need to be subtle. You need to find out: Who was late to the feast? Who left early? Who looked particularly pale or distracted during the main course?"
"But Professor," a Slytherin girl asked, "couldn't the culprit have just created an alibi? A simple redirection charm?"
"They could have," Sebastian agreed. "But magic always leaves a trace, and people always notice small inconsistencies. Maybe someone's robes were wet because they'd been near the flooded second-floor bathroom. Maybe someone was breathing hard as they sat down. I want you to find those small 'fragments' of truth."
He looked at the class, his voice becoming more serious. "This is a tedious, boring job. It isn't glamorous. You won't be kicking down doors today. But if we find three people who weren't at the feast, and one of them was near the third floor, we have a lead. If we don't do this work, we're just guessing in the dark."
The students began to mobilize, grouping up by house. They felt a sense of purpose that the rest of the school lacked. They weren't victims waiting for the next attack; they were the shield.
"Remember," Sebastian called out as they headed for the door, "no one is above suspicion, but no one is guilty until we have the 'Magical Resonance' to prove it. And Harry?"
Harry stopped, looking at Sebastian.
"You're going to be the most important part of this," Sebastian said. "I want you to work with the Gryffindor team. You're the one who heard the voice. If they find someone who was acting strangely, I want you to tell me if their 'vibe' matches what you felt in that corridor. Your intuition is a data point, Harry. Don't waste it."
As the Auror Training Class dispersed into the halls, the castle began to feel like a giant, ticking clock. In the corridors, the seniors were stopping younger students for "casual chats." In the common rooms, lists were being made. The atmosphere was one of quiet, professional investigation.
Sebastian remained in the classroom, watching the last of the students leave. He knew that none of them would find the culprit. Ginny Weasley was too young, too quiet, and too controlled by the diary to be caught by a simple headcount. But that wasn't the point.
The point was to keep the students busy. To keep them observant. To make the Heir of Slytherin feel the walls closing in.