The morning mist still clung to the castle grounds when Severus Snape stood at the threshold of the staffroom, arms folded tightly across his chest. His eyes were sharp, scanning the motionless portraits that lined the corridor. Behind their gilded frames, even the paintings seemed quieter than usual.
Something was building.
He could feel it in the way the walls seemed to breathe, in the way shadows stretched farther than they should. The air in the dungeons had been colder last night. Not naturally, but magically.
Snape didn't believe in coincidences—especially not at Hogwarts.
"Another one," Professor McGonagall said, stepping beside him with a folded piece of parchment in hand. Her lips were tight. "Colin Creevey. Petrified. Found near the trophy room."
Snape said nothing, though the muscle in his jaw twitched.
McGonagall sighed. "We must inform the students. Dumbledore will speak again at breakfast."
"Warnings mean nothing if no one listens," Snape muttered. "They're children. They'll keep wandering where they shouldn't."
McGonagall looked sideways at him. "That includes your Slytherins too, Severus."
He didn't argue.
Because she was right.
---
Gryffindor Common Room
Harry had barely spoken since returning from Potions the day before. His fingers tapped nervously against the wood of his chair, eyes unfocused as Hermione quietly relayed the news to Ron.
"Colin," she whispered. "They say he had his camera up when he was found."
Ron grimaced. "It's getting worse. Who's next?"
Harry didn't answer. His mind was full of echoes—of hissing voices, of stone corridors, of eyes like frost in the dark. The voice in the walls hadn't returned, but its absence was almost more ominous.
Then there was Draco.
He hadn't spoken to him since their strange exchange in the corridor, and Harry wasn't sure what worried him more: the tension, or the silence that followed it.
He needed to know what Draco knew.
And he needed Snape to stop watching him like he was a lit fuse.
---
Slytherin Common Room
Draco stared at the same page of his Transfiguration book for nearly twenty minutes. Pansy tried to engage him with some ridiculous gossip about a Ravenclaw fourth-year sneaking out at night, but he barely registered her words.
Everything was blurred now—school, house rivalries, even his own pride.
He hadn't meant to care. But he did.
Every time Harry Potter looked at him like they were on the same side, something inside Draco twisted.
But he couldn't say anything. Not with Pansy watching. Not with Blaise smirking from the other couch.
Not with his own mind trying to talk him out of whatever this was.
And then, worse, there was Snape.
Always watching. Always knowing.
Draco could feel it in every glance.
And if Snape ever truly disapproved… Draco wasn't sure what side he'd end up on.
---
Later That Day – Snape's Office
Snape stood over a collection of broken glass and powdery residue from the sabotaged potion. He'd taken it from Harry's cauldron before Flitwick arrived to clear the classroom.
There was no question it had been tampered with.
He had his suspicions. A few Slytherins with bitter grudges and sharp instincts. But nothing concrete.
What troubled him more was that neither Harry nor Draco had been behind it. That was the first rule of Hogwarts sabotage—always traceable to student rivalry.
This time, it felt bigger.
Older.
More deliberate.
Snape ran his wand along the powdered edges. A faint shimmer responded. Traces of basilisk venom? No. Something similar, but weaker. Harmless in this dose—but telling.
Someone was testing the waters.
Snape's grip tightened on his wand.
They were running out of time.
---
After Supper – Library
Harry slipped between bookshelves, his heart racing slightly. He wasn't sure why he came here—only that Draco had been there before. Maybe he thought he'd find answers.
What he found instead was Snape.
The Potions Master stood between the Divination and Ancient Magic sections, fingers grazing a spine like he was searching for something long forgotten.
"Potter," he said, without turning.
Harry froze. "Professor."
"You're following a trail that will get you killed."
"I'm not—"
"You are," Snape interrupted coldly. Then he turned, face unreadable. "And you're not alone in doing so."
There was a beat of silence.
Then Snape added, more quietly, "Neither is he."
Harry's breath caught. "Malfoy?"
Snape didn't answer.
Instead, he tucked the book under his arm. "Be wary, Potter. Affection—if that is what this is—has a way of becoming vulnerability. And at this school, vulnerability can be fatal."
And with that, he swept away, cloak trailing behind him like a warning.
---
That Night – Outside the Great Hall
Draco caught up to Harry just as the last stragglers filtered out after dinner.
"I need to talk to you," he said, eyes flickering to Ron and Hermione across the hall. "Alone."
Harry nodded and followed him to a quieter alcove near the staircases.
"What is it?" he asked, trying to keep his voice even.
Draco hesitated. "I think someone's using the castle itself. Moving through it like… like a serpent in the pipes."
Harry blinked. "You heard it too."
Draco nodded. "I didn't want to admit it before. Thought I was going mad."
Harry leaned forward. "We need to find where it's going. Where it hides."
Draco glanced around and stepped closer. "And if we do… what then?"
"I don't know," Harry admitted. "But I'm not waiting around for it to find someone else."
Draco gave a thin smile. "Then I guess we're doing this together."
Their eyes locked, and for a moment, everything else—the fear, the school, the expectations—melted away.
"Yeah," Harry said quietly. "Together."