Once they stepped out of the passage, Regulus cast the Obliteration Charm, sweeping the floor clean of every footprint until no trace remained.
He glanced back at the hidden entrance one last time, then flicked his wand. The vines slithered back into place, covering the opening completely and restoring the wall to its former, unremarkable state.
Winter sunlight in the Scottish Highlands never lingered long. By the time they left the Astronomy Tower, dusk had already settled in.
When they returned to the Slytherin Common Room, the fire in the hearth was burning brightly.
Several fifth-years were gathered near the flames, speaking in low voices. Their eyes flicked toward the three of them as they entered, then shifted away as if nothing were unusual.
Regulus did not pause. He headed straight for the dormitory corridor.
The door shut behind them. Cuthbert tossed his robe onto his bed and turned, ready to speak.
Regulus lifted a hand to stop him.
"Do not mention today to anyone."
Cuthbert froze mid-breath.
"This is serious," Regulus continued, turning to face them both. "Hermes was struck by a curse of a very high level. If we are caught investigating it, explaining ourselves will be difficult."
"And if whoever is behind it discovers we went there, we could be the next Hermes."
Regulus was confident he could avoid the worst of it himself. Cuthbert and Alex could not.
Cuthbert's expression shifted. His fists tightened, but he did not argue.
Alex stiffened completely, his breathing turning shallow and quick.
"For the next few days," Regulus said, "pay attention to who visits the Hospital Wing to see Hermes. Do not ask questions. Just observe when you pass by. Note the names and how often they go."
"You think…" Alex's voice trembled. "The person who did it will visit him?"
"They will," Regulus replied. "Hermes is unconscious, but he is not dead. That distinction matters."
If he is alive, he might wake up. He might say something he should not.
If there is someone behind this, they must know whether Hermes can wake, when he might wake, and in what condition.
The Hospital Wing is the only place to get that information."
Cuthbert's eyes lit up. "So we just watch who goes the most—"
"Or who behaves strangely during visits," Regulus added. "Avoiding Madam Pomfrey. Lingering too long by the bed. Attempting to touch him."
Alex swallowed hard. "And we…"
"Attend classes. Live normally," Regulus said evenly. "Treat Hermes as an injured dorm mate. Visit if appropriate. Show concern. But keep your eyes open."
Cuthbert nodded firmly and thumped his fist against his knee. "Understood."
Once they had each returned to their beds, Regulus sat at his desk and began thinking.
Hermes had been wandering the castle at night since the start of term. Most likely carrying out a family task.
The passage beneath the Astronomy Tower had been sealed for centuries. The protective enchantments at the entrance were advanced. The task must involve something ancient.
There had been two sets of footprints. At least two families cooperating, or one family sending two operatives.
There was only one Mulciber in Slytherin. So likely two families.
Hermes was gravely injured but not dead. The attacker's intent was probably not murder. More likely to seize whatever they had been seeking and prevent Hermes from continuing.
If the two had explored together and reached something valuable, a betrayal at the critical moment would explain everything.
It would also explain why Hermes was injured but not killed. The other party may have wanted only to incapacitate him and complete the final step alone.
The risk lay here. If Hermes regained consciousness, he might name his partner.
Another possibility lingered. They could have triggered the curse accidentally. The accomplice might have fled to protect themselves. Or tried and failed to save him.
Regulus shifted to another question.
How much did the professors know?
Slughorn had gone to the Hospital Wing the previous night. He likely recognized the type of curse.
But had the faculty discovered the hidden entrance beneath the Astronomy Tower?
Dumbledore must have been alerted. As headmaster, did he know what lay below the tower?
If Hermes had been found inside the tower, the professors would surely investigate the surrounding area.
But what if he had been moved elsewhere?
A corridor corner. An empty classroom.
If the attacker wanted Hermes incapacitated but not dead, the most effective method would be to leave him somewhere easily discovered, ensuring timely treatment while distancing themselves from suspicion.
In that case, the faculty might still be unaware of the secret beneath the tower.
Regulus leaned back in his chair.
Outside the window, the Giant Squid drifted slowly past, one tentacle brushing the glass. Green light shattered into a thousand fragments in the water, flickering across the walls.
That was acceptable.
If the professors did not know, the entrance remained temporarily safe.
If the culprit intended to finish the task, they would have to return to the Astronomy Tower.
And they would return. The task was nearly complete.
All Regulus had to do was wait.
He did not need to break the stone door's protections himself. He did not need to risk whatever lay beyond.
He only needed to identify the accomplice.
And follow.
---
"Mr. Black, Mr. Cuthbert and Mr. Rosier. A word in my office."
The next day after Potions, Professor Slughorn called them over.
Cuthbert and Alex both glanced at Regulus.
Regulus slid Magical Drafts and Potions into his bag and fastened the clasp. "Of course, Professor."
They followed him into his office.
"Sit." Slughorn gestured to three chairs before the desk and settled into his own seat, folding his hands over his stomach.
"I have a few questions regarding Mr. Mulciber."
Cuthbert straightened. Alex lowered his gaze slightly.
Regulus sat steady, eyes level.
"When did you last see Mr. Mulciber?" Slughorn's tone was light, but his gaze was sharp.
"The morning before yesterday," Cuthbert answered quickly. "In the Common Room. He said he was going to the library."
Slughorn turned to Alex. "And you, Mr. Rosier?"
"I… the same morning," Alex said faintly. "In the dorm. He changed clothes and left."
"Mr. Black?"
Regulus paused briefly before replying. "I did not see him that morning. The last time was three days ago, outside the Charms classroom. He walked past in a hurry and did not greet anyone."
Slughorn nodded. "Has Mr. Mulciber shown any unusual behavior recently? Mood changes? Strange remarks?"
"He has always been like that," Cuthbert said, frowning. "Quiet and brooding."
"Did he mention going anywhere specific? Or show interest in anything particular?"
Alex shook his head. "No."
Regulus did the same.
Slughorn studied them for a long moment. The fire crackled softly. In a jar on the shelf, a Swooping Evil larva rolled onto its side.
"My boys," Slughorn leaned forward, lowering his voice. "This is a serious matter. The curse Mr. Mulciber suffered is highly unusual. We do not wish to see more students drawn into danger.
If you recall anything, even something that seems insignificant, you should tell us."
Alex's lips parted slightly. Regulus flicked him a warning glance.
"Professor," Regulus said calmly, "we truly do not know anything. Hermes has been keeping to himself lately. He rarely spoke with us."
Slughorn leaned back again, fingers tapping lightly on the desk.
His eyes moved across their faces and lingered on Regulus.
"Very well," he said at last, a smile returning. "If anything comes to mind, my door is always open. You may go."
Once they were outside, Cuthbert let out a long breath.
"Does he suspect us?" Alex whispered, glancing back at the closed door.
Cuthbert shot him an irritated look. "Suspect us of what? That we attacked him?"
"Just a test," Regulus said as they descended the spiral staircase. "Without evidence, and with consistent answers, he has nothing."
"But we clearly—"
"We know nothing," Regulus interrupted evenly. "Remember that."
The next two days passed as usual.
Regulus rose at seven, washed, adjusted his robe, and went to breakfast.
In Charms, Professor Flitwick explained advanced applications of Wingardium Leviosa.
Regulus sat in the front row. His wand traced a precise arc through the air. A thick copy of Magical Theory lifted from a bookshelf across the room and glided toward him, settling silently onto his desk.
"Perfect, Mr. Black!" Flitwick clapped while standing atop a stack of books. "Five points to Slytherin!"
After lunch came History of Magic. Professor Binns droned on about goblin rebellions in the same monotone as always.
Regulus recorded key dates and treaty names while mentally refining a variation of Protego he had been considering.
If the Shield Charm could be restructured into a filtering lattice, allowing harmless matter through while blocking malicious magic, what adjustments would the magical framework require?
At three in the afternoon, he arrived precisely on time at the entrance to the Hospital Wing.