Felix walked down the spiral staircase with nothing in his hands. He was always like this, unlike other professors who carried books and test papers.

When he passed the castle administrator's office on the first floor, he heard Lupin's voice.

"...I'm sorry to bother you. If you can find it, please let me know."

Lupin's thin figure came out of the office and passed by Felix. "Hello, Professor Hep." He was stunned for a moment and said with a smile.

"Hello, Professor Lupin, you look good." Felix replied.

When he left, Felix knocked on Filch's office door, "Mr. Filch, are you there?" The door was pushed open, and Filch's face appeared from the shadows, staring at him with a pair of goldfish eyes.

"It's Professor Hep, I thought..." He muttered and opened the door. Felix followed behind. This was a rather small room, next to the castle's entrance hall.

There were no windows in the room, and even in the daytime, it was dim and cramped. The only light source was a green lantern hanging from the ceiling. There were many wooden filing cabinets lined up along the walls, some of which were already stuffed to the brim, with yellowed and old parchment sticking out from the gaps.

There were a few chairs in the office, but Felix had no intention of sitting down. He secretly cast an air freshening spell on himself, finally getting rid of the ubiquitous fishy smell.

Felix looked at a skinny cat on the table, its eyes were big, bulging, and sparkling.

"She looks very human," Felix said.

Filch was very happy that he used the word "she". His chin trembled as he said, "You will never find a smarter cat than her. If you ask me, she is more like a human being, or even better than a human being... At least she will not break the school rules and will help you."

Felix listened patiently to his description of how Mrs. Norris patrolled the corridor alone (cat?). He did not continue until Filch was out of breath, "But she looks a little malnourished."

Filch's voice was hoarse, as if no one had ever asked this question before. He stammered, "She is a little picky about food. I have advised her, but she only eats the fried fish I make..."

"I have some nutritional supplements here. The formula is very clever, and the key is that there is no harm." Felix said, his right hand brushed the ring on his left hand, and a square wooden box appeared in his hand.

He opened the lid of the box, took a quick look, and said with some regret, "Only half is left..."

Filch hesitated and said, "Noris may not like it--" He took out a small glass bottle from the square wooden box, opened the stopper, and a strange fragrance spread, diluting the fishy smell in the room.

Mrs. Norris immediately raised her head and stared at the glass bottle with a longing expression.

However, it did not move, but looked up at Filch. Filch said, "It's okay, Norris, drink it."

The cat immediately made a creepy cry, jumped off the table, ran quickly to its owner, stretched out its tongue to lick the bright red liquid in the bottle, and licked it until the last drop, then stretched lazily with satisfaction and made a "purr" sound.

Filch's eyes flashed with a strange light, and he couldn't help saying, "Norris has never been like this. She disdains the tonics in the pet shop."

Felix smiled and explained, "The formula comes from a potion master who was awarded the Second Class Order of Merlin. It was left by Professor Belby. Although he just made it casually, the effect is definitely far better than the products on the market."

"The formula-"

"I can give it to you. The preparation method is very simple, and you don't even need to use a wand, but you may use some dragon blood."

"That's nothing." Filch said quickly.

"Do you have any parchment here?"

"Yes..." Filch swiftly opened the drawer and took out a stack of blank parchment. Felix hooked his finger and let a piece of parchment float in front of him. As he stared, a string of smooth letters automatically appeared on the paper.

During this process, Filch kept staring at the parchment in the air, and his hands with protruding joints twisted together. Felix asked casually: "By the way, I just saw Professor Lupin."

"Yes." Filch repeated unconsciously.

"He came here--"

"To ask for confiscated things," Filch said, his eyes still fixed on the parchment, "Professor Happ, don't blame me for instigating... He is not a good person."

"Why do you say that?"

Filch came to his senses. He glanced at the door vigilantly and said in a low voice, "He was not honest when he was in school and loved to break school rules... Of course, not as much as his two friends, but I know him well. He is the one who came up with bad ideas."

He looked at Felix and complimented, "Unlike you, you were a decent person when you were in school--"

Felix said with some amusement, "I got into a lot of trouble when I was in school." Filch said

cunningly, "It's different--Sir, it's different. You never cause trouble for others unless trouble finds you first." He pointed to the filing cabinet by the wall, "There's a drawer there that belongs to them-Lupin and his interesting friends. If Hogwarts hadn't abolished corporal punishment..."

He muttered dissatisfiedly, "Mr. Pringle is in luck, unlike me. Oh, Pringle is the former castle manager. He left behind a lot of tools, and I kept them all."

Felix looked at the carefully wiped iron chain hanging on the wall and shook his head. It was reasonable for the little wizards to hate Filch. He knew very early that Filch liked to punish students physically. Even if physical punishment was abolished, mental punishment was still retained.

And Filch was trying every means to innovate and develop this skill.

"Mr. Filch, you just said that Professor Lupin came to get his things back--"

"Yes, more than ten years ago, he and his friends were wandering around. I questioned them and found a suspicious, layered parchment from them. I suspected that there was some secret hidden in it, so I confiscated it."

Filch said, half of his face twitched, "You don't know how bad they are. After the parchment was confiscated, they still looked indifferent," he said viciously, "They must think that I can't crack the secret on it and will throw it away, so that they can secretly pick it up, but-I didn't, instead I kept it and locked it in a drawer."

"What about the parchment now? Did you give it back to Professor Lupin?" Felix asked curiously.

"...lost," Filch said dejectedly. "I don't remember when I lost it, maybe they took it themselves."

"But you said Professor Lupin came to ask for it..."

"Who knows, maybe his friends didn't tell him, or other little wizards stole it from me over the years." Filch said with regret.

The parchment in the air fell down, and Felix handed the formula to Filch, "Please keep it."

"Thank you, thank you--"

"You're welcome, Mr. Filch, I got what I wanted too."

Filch looked at him in astonishment, and Felix smiled and said, "Look, isn't Mrs. Norris very satisfied?" He pointed to the cat at his feet, which was lazily rubbing against his trouser legs.