Peeves was talking about the time when Sebastian taught Harry the Disillusionment Charm.
At that time, Sebastian wanted to go to the Forbidden Book Area to find a way to lift the Black Magic Curse and save the suffering Annie. However, because Peeves reported him, Sebastian became the least popular person in the library, and the school even placed a magic spell to prevent him from entering.
So from that time on, Sebastian held a grudge against Peeves, and even invented a spell to deal with him.
"Come on, Mr. Saru!" the students cheered together for Sebastian—no one was cheering for Peeves or speaking for him, because he was the least liked person among the students.
"I'm getting beaten up, you bunch of stupid little wizards!" Peeves shouted in struggle.
"Ceeeeeeeeeb!" the Weasley Twins shouted, drawing out the sound.
"What are you doing?"
Professor Dumbledore's voice sounded.
"Sorry, Professor," Harry said. "We were watching Peeves get beaten up."
"Hey, Professor Head!" Peeves shouted, "Can you help me get this annoying Slytherin ghost away from me?"
"Mr. Saru." Dumbledore called out.
Only then did Sebastian let go of Peeves and walked away proudly.
As he left, he told the students that if Peeves started causing trouble again, they should come find him in the basement.
Peeves was disheartened, while the students were beaming with joy.
"Alright, let me through." Dumbledore said.
The Gryffindor House students finally squeezed together to make a path.
"Professor McGonagall, please go to Mr. Fitch immediately and tell him to search for the Sphinx in the castle." Professor Dumbledore said, turning back. "Also…"
Before he finished speaking, a voice rang out from the crowd.
"The Sphinx is back!" someone shouted.
Everyone walked down the stairs, making a path for the Sphinx's massive body.
The Sphinx at the doorway wasn't in the human-face shape, but in the eagle-head shape—he strutted in proudly, like a victorious warrior.
People could see he was holding a tuft of black hair in his mouth.
"Someone tried to break into the Gryffindor dormitory, Headmaster." The Sphinx spat out the tuft of hair and happily told Dumbledore, "I am pleased to tell you, Headmaster, that I chased that person away, and grabbed a tuft of his hair in the process—"
"Glad to hear the news." Professor Dumbledore nodded and said, "Thank you for your contribution to the school's safety, Sphinx."
"It's my duty." the Sphinx said with a grin.
"Well then, do you know who the intruder was?" Dumbledore asked.
"Do you think he'd tell me?" the Sphinx retorted.
Dumbledore raised an eyebrow but did not continue to ask further.
But he had already guessed who might have attempted to force their way into the Gryffindor Common Room.
After thinking for a moment, Dumbledore asked all the Gryffindor students to return to the Great Hall, and ten minutes later, students from Hufflepuff, Ravenclaw, and Slytherin houses also arrived. These students looked completely bewildered.
Everyone was whispering to each other, guessing why the Headmaster would gather everyone in the Great Hall.
Did he have some important announcement to make? People quietly speculated, with someone irresponsibly guessing that Dumbledore was about to announce an early Christmas break—
Ha, dreaming much?
Once everyone was standing properly, Professor Dumbledore raised his hand.
Seeing this, everyone shut their mouths, turning the Great Hall silent.
The professors and I will be conducting a thorough search of the castle," Professor Dumbledore said to the students, at this time, Professor McGonagall and Flitwick closed all the doors of the Great Hall, "For your own safety, you may need to stay here overnight—I ask the Class Prefects to stand guard at the entrance of the hall, and the Presidents of the Boys' and Girls' Student Councils to stay inside and manage everyone, and report to me immediately if anything happens—"
He added this to Percy, who looked proud of his important role.
"—to find a ghost to send the message to me." Dumbledore said to Percy.
"Look, the Head Boy's privilege." Fred murmured quietly, "That's the Head Boy, the student with the biggest head in the Headmaster's eyes…"
The students nearby couldn't help but snicker.
Professor Dumbledore paused and looked in the direction of the laughter but didn't say anything.
He turned around, about to leave the Great Hall, then stopped and said to everyone, "Oh, by the way, you will need—"
He waved his magic wand casually, and the long tables flew to the sides of the hall, standing against the walls; with another wave, hundreds of purple sleeping bags covered the floor.
"You need something to help you sleep well in the Great Hall." Professor Dumbledore said to everyone, winking as he walked out of the Great Hall.
Of course, as the Headmaster, he never forgot to close the door.
The Great Hall immediately burst into a hubbub of excited chatter, sounding both noisy and exhilarating.
Since the professors were not in the Great Hall, the students were in an unsupervised state—the basic situation now was that the Gryffindor students were busy telling the other students what had just happened, while the uninformed students listened in wide-eyed excitement.
When they heard that Sirius Black had broken into the Gryffindor Common Room, everyone was thrilled.