Dumbledore thought for a moment and said: "This involves a terrible dark wizard in the fifteenth century, Ekrizdis, who is the earliest known resident of Azkaban, when it was still just an unknown island on the North Sea, blocked by hidden magic.

Although there has never been a shortage of dark wizards known as 'evil' throughout history, Ekrizdis' evil is rooted in his bones, and he has no semblance of compassion toward anything that exists, and it was him who created the species of Dementors by cruel means."

Felix asked in surprise: "Dementors were created by a wizard? It's like a five-legged monster?" He didn't know anything about it, it's definitely a hidden secret in the wizarding world.

"Five-legged monsters are the product of accidents, but dementors are not." Dumbledore shook his head, "By the time Ekrizdis died, and when the concealment wards failed, people found out what he had done, but the dementors already had become a separate species, only a dozen at first, but they could breed and divide like a fungus, and regular spells are nigh-ineffective."

Felix asked suspiciously, "If that is true, their numbers should have flooded beyond control long ago, but they are actually scarce and used by the Ministry of Magic?"

Dumbledore explained: "The Ministry of Magic and the Dementors have more of a cooperative relationship, and that creature seems to have a magical sense of community, their numbers are always maintained within a certain range, but as soon as they are reduced to a certain level, they will divide themselves, perhaps this is also a way of reproduction?"

Felix pretty much understood the way the dementors existed, and he couldn't help but inquire, "What other spells work besides the Patronus charm? I mean, to kill the dementors completely?"

"It's hard, Felix, it's hard," Dumbledore said.

Felix also wanted to continue to ask questions, but Dumbledore obviously do not want to talk more, their conversation ended quickly.

...

In the early morning, the young wizards woke up from their beds, unaware of the events of a few hours ago.

Harry, Ron, and Hermione sat at the long Gryffindor table eating breakfast, and occasionally a few owls flew in as Hermione looked out of the great hall with an expectant gaze.

"Are you expecting any letters?" Ron asked.

"Oh, I purchased a book from Flourish and Blotts Bookseller through the owl." Hermione said absent-mindedly, "It doesn't look like it's going to arrive today."

Ron saw that Harry is somewhat depressed, so he suggested, "We can go to Hagrid's place as a guest for the weekend when your training is over, to be honest, the three-headed dog after becoming smaller is particularly cute, and for the first time I agree with Hagrid's aesthetics ..."

Harry also moved, he perked up and said, "maybe later, Wood probably will have the training until dark."

Ron shrugged, "Let's hope Hagrid doesn't kick us out again." At the beginning of the school year, fearing Hagrid's expulsion, they visited him at night in their invisibility cloaks, only to have Hagrid personally escort them back to the castle and warn them that they could only visit him during the day.

Hermione just wanted to make a comment, but Professor McGonagall suddenly entered the great hall, and she exclaimed, "Potter, come here!"

Harry put down his knife and fork in bewilderment, what mistake had he done again, Ron and Hermione looked at each other and followed together.

"Weasley and Granger ... you guys..." Professor McGonagall did not drive away the uninvited two, she looked at Harry with a serious expression: "Where is your sneakoscope? The one that is aimed at Black!"

Harry cautiously pulled out the pocket sneakoscope from his pocket, it laid serenely in his hand, Professor McGonagall visibly relieved.

"Did something happen, Professor?" Hermione asked in a small voice.

"It shouldn't be kept from you anymore, Potter," Professor McGonagall said, "I know you're probably shocked, but I have to tell you that Black--"

"I know all about it," Harry said in annoyance, "I know he's after me, that's why he broke out of Azkaban! I also know he was close to my father, even his best man, and he, he's still-" Harry couldn't go on, the thought of the word godfather made him feel insulted, including his deceased parents, insulted by it.

Professor McGonagall seemed very surprised and looked at him with wide eyes, "I see, well, I thought-"

"Then you should understand why I made you carry this sneakoscope with you, it will protect you." She pursed her lips, "Just earlier today, before dawn, the castle's sneakoscope triggered an alarm."

Harry stammered, "Is it, is it the sneakoscope I'm holding? But it has been in my pocket, there is no change, ah?"

Ron's face also showed a shocked expression, he covered his pocket with a death grip and whispered, "Don't move, Scabbers!"

Professor McGonagall clenched her fist briefly, and seemed to be hesitant whether or not to tell, before, to keep it a secret, only Felix, Dumbledore and she knew that there are not one but three sneakoscope, but now it is no longer a secret.

Hermione on the side answered: "Professor McGonagall, I have seen it with Professor Hap, there were three identical sneakoscope, the other two should be arranged in other places? I guess it's the entrance of the castle ..."

Professor McGonagall sighed, "Well, Granger, just as you said ... one at the front door and one at the back."

Harry said, not knowing whether to be grateful or disappointed, "So, he wandered around the castle entrance before?"

"I think so," said Professor McGonagall: "The professors were up early and searched the castle thoroughly, but found nothing. The portraits in the castle also failed to discover any stranger, which means ..."

"He knew he was exposed and ran away early," Harry said.

"That's right, Potter." Professor McGonagall said, "Now that you're aware of all this, I'm sure you're prepared for the fact that some activities aren't suitable for--"

"Hogsmeade -" Harry exclaimed, his heart rising to his throat.

Hogsmeade is a village made up solely of wizards, where young wizards in their third year and above can visit on specific days each school year with the permission of their parents or other guardians.

He was discussing this with Ron last night when he told him he couldn't able to convince Aunt Vernon, so Ron had suggested he should ask Professor McGonagall for permission.

Now it looked like it's likely to be a failure.

Professor McGonagall glanced at him and said with a serious expression, "Of course, you can't go to Hogsmeade, I'm talking about Quidditch. Honestly, it's just too dangerous to let you train, even with the other players around it won't be possible for them to deal with Black, even if he is all alone."

"Professor McGonagall," Harry couldn't help but exclaim, "what does this have to do with my training?"

"Of course, it has something to do with the fact that Black is most likely hiding in Hogsmeade right now, or deep in the Forbidden Forest." Professor McGonagall blurted out a bolt out of blue. "The Quidditch pitch is too far from the castle, and if anything really happens, we might not be able to rescue you just in time."

"But, but ..." said Harry, somewhat bewildered, he had started this year's training, three times a week, and Wood had ambitiously told him to aim for the second Quidditch Cup during his term, as his graduation present.

The other players, too, seemed confident because of last year's victory.

But now the first game had yet to begin, and the trophy is going to become a blur?

Harry suddenly thought of something, and he asked eagerly: "Professor McGonagall, what if a professor is watching us, such as Madame Hooch ..."

Professor McGonagall pursed her lips and did not speak.

"Please ...," Harry said pleadingly.

"All right," Professor McGonagall loosened her lips, "I will ask Madame Hooch to supervise your training, and you must return to the castle immediately before dark, and I will drop by when I can."

She left in a hurry, as she had a lot to deal with because of this dawn's accident.