Slytherin's Chamber of Secrets (IV)

The moment he entered, he pointed his wand behind him, and the door shut with a bang. Then he cast a Silencing Charm, a Muffliato, and finally a spell to drive away eavesdroppers.

Only after completing that series of precautions did he walk to Dumbledore's desk, pull out a chair, and sit down.

His movements were smooth and practiced. Clearly, this was not his first time.

Dumbledore watched him finish all of it, the corner of his mouth lifting slightly. "Do you think someone will be listening in on our conversation?"

"One can never be too careful," Severus Snape said in a low, hoarse voice, as though sandpaper were scraping against his throat. "Especially after tonight."

"After tonight." Dumbledore repeated the words and nodded. "Tell me what you think."

Severus Snape did not answer immediately.

He took a small crystal vial from the inner pocket of his robes, removed the stopper, and tipped back a mouthful. It was Revitalizing Potion—he had expended a great deal of magic tonight. Though he had not participated in the battle directly, maintaining those protective and detection spells in secret had also drained him.

"Let's begin with Filch." Severus Snape set down the bottle, his tone as calm as if he were reciting the dinner menu. "He has changed. Or rather, he was never the person we thought he was."

Dumbledore said nothing, merely gesturing for him to continue.

"A Squib." The corner of Severus Snape's mouth twitched slightly, as though the word itself carried a certain irony. "A Squib who had served as Hogwarts's caretaker for over fifty years suddenly became a... wizard capable of fighting both Minerva and Filius, two dueling masters, at once tonight."

He put particular emphasis on the word "wizard," lending it an indescribable significance.

"Not an ordinary wizard," Dumbledore