After arriving at the library, Dudley headed straight for the Restricted Section.
There was an imposing iron gate separating it from the other areas. Only with a note signed by a professor could one enter to borrow the required books.
"What are you doing?" Before Dudley could approach the Restricted Section, a stern voice rang out sharply.
Madam Pince, the librarian, emerged from behind a towering bookshelf and quickly positioned herself before Dudley.
"Hello, Madam Pince. I'd like to examine the Restricted Section," Dudley said directly.
"What did you say?" Madam Pince thought she had misheard completely.
"I want to look at the Restricted Section," Dudley repeated clearly.
"What kind of ridiculous joke is this! Get out!" she snapped.
"Get out right now!"
Madam Pince waved her feather duster aggressively, attempting to shoo Dudley away.
"Wait, Madam Pince. I'm currently serving as a substitute professor. I have the right to read books in the Restricted Section," Dudley quickly explained, using his hand to block the feather duster she was waving at him.
"Substitute professor? How would I know that? If the school hasn't officially notified me, it doesn't count!" she declared.
"Get out, get out immediately!"
Without any room for discussion, Madam Pince directly drove Dudley out of the library and glared at him fiercely to prevent him from sneaking back in when she wasn't paying attention.
"I'll go get proof from Professor McGonagall right now," Dudley said with obvious frustration.
"I need proof from Professor Dumbledore. He's the headmaster of Hogwarts!" Madam Pince said coldly.
She completely refused to believe Dudley's claims.
Although she knew Professor Dumbledore had given Dudley some privileges, these privileges didn't include access to the Restricted Section.
Dudley helplessly rolled his eyes and turned to leave.
Unless he wanted to engage in conflict with Madam Pince, he wouldn't be able to enter not just the Restricted Section today, but even the regular library areas.
"What a hassle," Dudley muttered with annoyance.
This librarian, Madam Pince, like the school caretaker, Filch, seemed to genuinely dislike students, always wanting to catch evidence of them breaking rules and then punish them severely.
Dudley looked at the time. It was already quite late. Going to disturb Professor Dumbledore now seemed somewhat inappropriate.
After considering his options, he temporarily abandoned this idea and began patrolling the castle.
Around nine o'clock, Dudley had finished most of his patrol and was walking toward Gryffindor Tower.
Suddenly, Dudley's brow furrowed with concern.
He felt something unusual had appeared in the castle, making him sense a hint of danger.
But this feeling was very faint and quite far from his current position. It was a very subtle sensation.
"What's going on? What is it?" Dudley frowned with growing concern.
He stood perfectly still without moving.
Spiritual power began spreading out from his body, carefully sensing the changes around him.
"Danger, evil, unsettling..." Dudley clearly felt some abnormal auras permeating the castle.
"What's happening in the castle?" Dudley's expression kept changing with worry.
As Hogwarts' sheriff, he had formed a deep mystical connection with this area. Even the slightest changes would alert Dudley through supernatural means.
And now, he had that exact feeling.
Dudley raised his hand and pressed it against the stone wall, his whole body leaning against it.
He wanted to sense the situation in the castle more precisely.
"It feels like something has been added to the castle... very dangerous, and with a distinctly evil aura... Could another dark wizard have infiltrated?" Dudley said with obvious concern.
He felt that entity seemed to be moving, and quite rapidly, but it appeared to be far from his location. He couldn't accurately identify what that thing was.
"Mr. Dursley, what are you doing?" A cold voice came, interrupting Dudley's concentration.
"Professor Snape," Dudley said, recognising who had arrived.
Snape glared at Dudley with obvious suspicion, then carefully examined the wall Dudley had been pressed against.
"Did you discover dark magic on this wall, or did you sense a dark wizard infiltrating the school?" Snape asked with complete expressionlessness.
"You're absolutely right. I did discover certain problems in the castle. It might be a dark wizard, or it might be something else entirely," Dudley said with complete honesty.
Snape frowned with obvious concern.
He wasn't sure whether Dudley was being serious or playing some kind of game.
After all, Dudley did have demonstrated talent in this area. He could detect evil auras.
"Are you serious?" Snape asked again with intensity.
If something involving dark magic or dark wizards had really been discovered, they would have to be extremely vigilant.
"I'm completely serious. I was just about to track it, but Professor Snape interrupted me. Now I can no longer find that feeling," Dudley explained.
A flash of anger crossed Snape's pale features.
"Dursley, do you think you're being humorous?" Snape was visibly annoyed. He felt Dudley was making fun of him.
"I'm seriously answering your question," Dudley replied with calm directness.
Snape narrowed his eyes and said with ice-cold menace, "Just because you're temporarily substituting for a few days doesn't mean you're actually a professor, Dursley!"
"In front of me, you'd better be extremely careful."
"Otherwise, who knows when I might add something special to your meals."
Dudley looked at Snape defiantly and said, "If you have that kind of free time, you'd be better off thinking about how to properly manage your Slytherin students and stop them from bullying others."
Snape's expression instantly became extremely ugly, and his breathing became noticeably rapid and agitated.
Swoosh.
He reached out to grab Dudley's chest with sudden violence.
However, Dudley reacted quickly, directly dodging and drawing his wand to point at Snape.
"You dare cast a spell on me? Come on, if you're capable, try it! Let me see just how much strength you really have! Come on!" Snape roared with uncontrolled fury.
His emotions seemed completely out of control, becoming very agitated, with no colour left in his ashen face.
Dudley's expression also looked grim.
He didn't understand why Snape's emotions had fluctuated so dramatically, like a cat whose tail had been stepped on, directly bristling with explosive fury.
"What's wrong? Don't you dare?" Snape taunted.
"Or don't you know how?"
Snape pressed forward step by step. He had also drawn his wand with threatening intent.
"Do you need me to teach you?" Snape's expression contained anger, loss of control, and bitter resentment.
Dudley felt magical power gathering dangerously. Snape really intended to cast a spell on him.
"Expelliarmus!" Dudley chose to strike first, directly casting magic.
A red light shot from Dudley's wand, heading straight for Snape with precision.
But Snape's wand flicked lightly, and a burst of brilliant light erupted, forming a protective magical barrier.