As he had ordered, everyone from his House and also from Ravenclaw was in the Transfiguration Courtyard ten minutes before their class.
Under his guidance, they all entered the room, took their seats in an orderly manner, and curiously watched the tabby cat that was sitting on a small table on the teacher's platform.
It was a silver tabby cat with distinctive square markings around her greyish-green eyes, and it was sitting a little too still.
Altair kept looking into its eyes for a few minutes, and when the clock tower rang at three o'clock, he stood up from his seat and climbed the teacher's platform, approaching the animal who was staring at him.
He already knew what was going on and curiously leaned over it, scratched its chin, and also planted a kiss on its head.
He grinned when he saw the cat's eyes narrow at him, and stepped back when it jumped up and transformed into Professor McGonagall, shocking the entire class.
Altair, however, kept a smile on his face.
"Oh, Professor, I did not know it was you... I promise," he playfully said, and the students broke out of their trance and either giggled or chuckled, trying to hold back their laughter.
He had kissed the Professor!
"For some reason, I don't believe your words, Mister Black. However, you may take your seat."
"Thank you, Professor." He politely bowed to her and returned to his seat.
Cho and Aurelia grinned when they saw him grin, and quickly covered it when he sat down.
Everyone waited for their Professor to speak, and when she did, she sounded a little upset.
"Transfiguration is some of the most complex and dangerous magic you will learn at Hogwarts. Anyone messing around will leave this classroom and not return." Her voice was sharp, making their hearts skip a beat.
Then, without warning, she transfigured her desk into a pig, let it oink once, and turned it back. This display of magic left the Ravenclaws stunned, and the Slytherins were intrigued.
"How many of you have read the first chapter of A Beginner's Guide to Transfiguration?"
At her question, everyone in the class raised their hands.
"Mister Black, stand."
Altair slowly rose to his feet and kept the smile on his face. He knew he was being targeted for his earlier mischief, but he was not worried.
"What's the First Law of Transfiguration?" she asked.
"The Law of Elemental Stability."
"Explain it."
"The more dissimilar the base elements between the object and the intended target form, the greater the magical strain and risk of instability. For example, if you try to transform something organic into something inorganic, you end up with magical strain and a risk of instability. This does not mean that you cannot do it, but you need to be careful with what you are doing. Transforming wood into stone will prove to be easier than transforming stone into flesh. On the other hand, you can transform wood into flesh as they are both organic, but this is still difficult as the two elements still have a lot of differences and you need advanced Transfiguration knowledge, including the understanding of elements, to pull it off."
"What would have happened if I kept the table in that pig form for an hour?"
It was not a question for First Year students, and he smiled in his heart.
"You only kept it in the pig form for a few seconds and it has affected the wood's decay rate. If you kept it in the pig form for an hour, the decay rate would have increased even more. However, to determine that decay rate, we need to know which type of wood it is, how old it is, when it was harvested, and what kind of polish, if any, has been applied to it to preserve it. We will also need to check for any enchantments placed on it and several other factors need to be accounted for as well. However, the violation of the First Law always leads to a faster decay rate."
Minerva stared at him silently when he finished speaking.
"Second Law."
"Law of Mass Conservation."
"Explain."
"Magic cannot destroy or create mass during Transfiguration. It may only redistribute or disguise it. A pebble transformed into a button will weigh the same. A pebble transformed into a table will weigh the same. Its size may increase, but it will not be heavy or as dense. It will be hollow, fragile. Violation of this rule leads to unstable results and even magical backlash."
"Any way around it?"
"Yes, you can magically reinforce things to compensate for the faults. However, an unstable Transfiguration will require a lot more magic than usual to reinforce it. The chances of backlash sharply rise, and it is deemed ill-advised to try and reinforce an unstable object. The backlash can even be fatal."
Professor McGonagall smiled and nodded her head. Her mood had visibly improved.
"Third Law?"
"Law of Magical Reversibility."
"Explain it." She folded her arms on her chest and glanced around the classroom.
"All Transfiguration must remain theoretically reversible unless cast with the intent of permanence," he answered and continued with the explanation. "Temporary Transfiguration reverts naturally over time or under duress. Permanent Transfiguration requires specific intent, power, and the resulting magical signature stays. A permanently transfigured object and the witch or wizard who created it can always be identified based on these magical signatures. As for Animagi and human-to-object Transfigurations, they must always be reversible to avoid permanent damage or death."
"Good. Tell us about the Fourth Law now."
"The Law of Conscious Boundaries. Sentient beings may not be created or conjured through Transfiguration. You can transfigure a cushion into a dog, but it will never be alive, only merely enchanted to act alive. True consciousness cannot be formed or faked through this branch of magic. This is why Cross-Boundary Transfiguration, object to human or human to object, is highly difficult and even more dangerous."
"Fifth Law."
"The Law of Magical Imprint. All transfigured matter retains its original signature which skilled witches and wizards can detect. A quill transformed into a flower may look perfect, but it retains its magical fingerprint. This is what enables Transfigurations to be reversed and why illegal Transfigurations are traceable."
Professor McGonagall happily smiled at him.
"Impressive, Mister Black."
Altair politely bowed to her in response and smiled.
"Can you tell the class about one thing that they must never do?"
"Food. Don't transfigure things into food, and if you do, don't ever eat them. You might end up dead."
She happily clapped her hands, and the class followed her lead to applaud Altair.
"Twenty points to Slytherin," she announced, and a hum was heard.
The class continued with the Professor taking questions from the students about the Five Laws of Transfiguration, and then she summoned matchsticks onto their tables and taught them an incantation.
"Transfiguro."
Quite a few students in the class managed to get it right on the very first attempt, and by the end of the class, everyone had succeeded in it.
Professor McGonagall was strict, even stricter than Professor Tonks, but she was also very kind and patient.
At five o'clock when their day ended, she too praised them for their talents and expressed her high expectations of them.
Once they came out of the class, Altair dismissed the Slytherins, who happily went their separate ways to do things they wanted to do.
He, Aurelia, and Cho decided to return to the dormitory, and after freshening up, they sat down in the common room to play chess.
Well, it was just the girls playing against each other. Altair sat facing the fireplace with his eyes closed, seeing the world from Strix's eyes as it flew over Hogwarts and beyond.
"Checkmate," Aurelia happily said when she won the game, and even though Cho wanted to have another, it was almost seven o'clock and they needed to leave for dinner.
The other Slytherins were all ready as well, and most had not returned to the dormitory.
Only some First Year and Second Year students were present, and they followed Altair out. They made their way up the dungeon, but just when they were about to reach the ground floor, he stopped.
"What's wrong..." Cho wanted to ask but he signalled her to stay quiet and took out his wand.
"Repulso Reflectum..." he whispered the incantation and waved his wand, sending out a wave of protective bubbles that covered every single student's body and then turned invisible.
Once finished casting the spell, he put his wand back and continued walking.
Everyone stayed very alert but pretended to be unaware of any danger under Altair's instructions.
However, when they exited the first hallway, they suddenly heard the invisible barriers around them blink and pop, and they knew they had been attacked.
Since the one leading them did not stop, neither did they.
None of them knew who attacked them, and they all silently took their seats in the Great Hall.
However, the keen ones soon noticed a few Gryffindors missing. The most obvious of them were the Weasley twins.
Suddenly, a Gryffindor rushed into the Hall and whispered something in the ear of Charlie Weasley, the Seventh Year Prefect of his House.
The red-haired boy visibly tensed up and then stood up to approach Madam Poppy Pomfrey, the Hogwarts Healer, who was sitting at the staff table with Andromeda Tonks.
Both the ladies abandoned their dinner and quickly got up to go and check up on something, likely the missing Gryffindors.
Some of the Gryffindors glared in the direction of the Slytherin table, but Altair and everyone else ignored them.
They finished their meal, not caring about all the chatter and buzz about what was going on, and then Altair led them out.
Gemma Fawley, their Prefect, who had finished eating early and had gone out to understand what was going on, informed them what was happening.
"Fred and George Weasley, Matilda Peakes, Lee Jordan, Piers Dunwell, Gideon Fairbrain, and Lena Vance are in the Ward. Someone attacked them with powerful hexes. Their hair is green and silver, their robes have 'Proud Muggle-borns' written on them, their noses and ears are enlarged like that of goblins, their voices are squeaky, and two of them have diarrhoea."
"Oh..." Altair chuckled, and those who now knew what had happened, felt chills up their spines.
They all stopped when they heard a few people rushing towards them, and when they turned around, they saw that it was a group of Gryffindors, led by their Prefects.
Seeing wands in their hands, all the Slytherins instinctively drew their own wands, and this forced the group to stop in their tracks.
"What's the meaning of this, Charles?" Gemma asked coldly, and glanced at the teachers who were rushing over.
"What's going on here?" A tall lady who was dressed in light armour under her robes, with shoulder-length silver and black hair, coldly asked.
Her presence was quite intimidating even though she was a good-looking middle-aged lady.
Professor McGonagall was right by her side and the two stepped in between them.
"Ask Charles and his gang, Professor Montclair. What are they doing on this side of the castle? And why were they approaching us with their wands drawn?" Damien Rosier spoke, and even the others who had just arrived there turned to look towards the Gryffindor goons.
"We did not mean any harm, Professor. We had our wands out for our safety." Charles calmly said. "They attacked my brothers and their friends, so I want some answers."
His words did make everyone frown, and Professor Montclair, who was the Supervisor of the Duelling Cup as well as the Professor of the Ethics, Honour, and Sociology programme, turned to look towards the Slytherins again.
"Did you attack them?" she straightforwardly asked, and all of them shook their heads.
Even Professor McGonagall did not believe that the Slytherins attacked those students, and her eyes settled on Altair.
"What happened, Mister Black?"
Professor Flitwick and Professor Snape also arrived and looked towards him.
"The Reversal Cloak Charm," he honestly answered, and the eyes of the Professors and even the Seventh Year students widened in shock.
In an instant, Professor McGonagall understood everything, and so did Charles Weasley, but he was more angry than embarrassed.
"There was no need to amplify it!"
"I didn't." Altair calmly said.
"Mister Black, you cast that spell?" Professor Flitwick was both impressed and horrified.
"Yes, Professor. My mother taught me this spell to protect myself from minor hexes, curses, and charms."
"It's an advanced-level spell. Only Seventh Year students can cast it. Whom are you kidding, Black?" a Gryffindor spat out loud. "I am sure it was you, Damien. Have some honour and admit it!"
The Slytherins stayed silent, and a few moments later, Altair took out his wand and effortlessly cast the spell.
"Repulso Reflectum."
Dozens of magical bubbles covered the Slytherin students and then went invisible, and those who witnessed the scene were too stunned to react.
Moments later, Professor Montclair took out her wand and cast the same spell on herself, and then she cast a spell on Altair.
"Depulso."
Both of their bubbles instantly blinked and burst, and the lady meaningfully looked at the young Black and his wand.
"You are just as tricky as your mother, Mister Black."
He brightly smiled at her words.
"May we leave for our dormitory now, Professor? I am sure if you ask those honest Gryffindor students why they wanted to harm us, they will give you the answer. They are very honourable people, after all. People who would never attack unsuspecting students," he sarcastically said, and then glanced at Charles and his group, who glared at him but then averted their eyes.
"Miss Fawley, lead everyone to the dormitory," Professor Snape ordered, and the Prefect acknowledged his words and then glanced at Altair.
The young Black kept staring at the Gryffindors for a few more seconds before he turned around and together with Gemma, led everyone to the dungeon.
All the other students who had gathered around were sent away too, and when only the teachers remained, Filius asked what was making him anxious.
"Did he amplify it, Victoire?"
"No. His magic is just that strong. It was likely not intentional. And we cannot blame him for what happened even if it was intentional. It's a defensive charm that only activates when attacked."
Minerva could only nod her head in sadness before she turned around to walk towards the Hospital Wing, followed by the rest of her colleagues.
She was very disappointed with the students of her House...