Detention Usually Didn't Work Like This

That evening, Gavin had barely returned from St. Mungo's when Professor McGonagall caught him.

Strictly speaking, "caught" wasn't quite right.

This had been arranged from the start—every Saturday, after returning from St. Mungo's, he was to serve detention in her office.

And since the Floo Network opened into Professor McGonagall's office, Gavin stepped out to find her waiting for him.

"Mr. Gu." Professor McGonagall glanced at him, her tone calm. "You're right on time."

"I generally don't show up late for things like this, Professor."

"Good." Professor McGonagall nodded. "That tells me you still have at least a basic respect for the rules."

Gavin almost said his main concern was whether being late would add another item to his bill. That, more than anything, had taught him respect.

But the professor was in the delicate position of deeply distrusting him while also worrying about him. In the end, he swallowed the heartfelt complaint.

A warm fire burned in the office.

A thick stack of parchment and a quill were already laid out on the desk, with an ink bottle beside them. Even the angle at which they sat suggested an orderly mind.

Gavin stepped closer. Sitting atop the parchment was a copy of Beginner's Guide to Transfiguration.

He immediately had a bad feeling.

Sure enough, Professor McGonagall spoke the next moment.

"Sit down and copy."

"...How much, Professor?"

"Chapters three through six to start." Professor McGonagall didn't look up. "If you have energy left, I wouldn't mind you copying the appendix too."

It wasn't an outrageous amount of work.

But it was more than enough to make Gavin suffer—and teach him what "don't blow up a tower for no reason" really meant.

Gavin sat down, picked up the quill, and stared at the heading on the first page for two silent seconds.

"Professor."

"Yes?"

"The point of detention isn't manual labor, is it?"

"Of course not," Professor McGonagall said. "The point of detention is to make sure you remember."

Professor McGonagall dismissed his objection without a shred of sympathy.

So Gavin lowered his head and began copying.

At first, it wasn't too bad.

He wrote quickly enough. Before he owned a Self-Writing Quill, he had always done his writing himself. But writing by hand was torture for someone accustomed to typing, and now he had to copy Beginner's Guide to Transfiguration. That took the torture to another level.

For someone whose mind moved quickly, copying a book was mindless work that couldn't come close to keeping pace. By the time his thoughts had circled the globe, he would look down and find he had copied only two lines. It was torture, plain and simple.

After half an hour, his wrist began to ache.

After an hour, he began to miss his Self-Writing Quill.

After an hour and a half, he had developed a profound new resentment toward the United Kingdom's Wizarding World and its fondness for making students copy things by hand as proof that education was working.

Professor McGonagall sat behind her desk marking assignments. At first, she paid him little attention.

But after a while, she couldn't help glancing up. Gavin had only recently returned from the hospital, after all.

His condition was plain to see.

He wasn't slacking off or scribbling carelessly. He was copying with painstaking care, his writing neat and precise, but his whole bearing radiated utter despair.

When he rubbed his wrist for the fourteenth time, Professor McGonagall finally set down her quill.

To be honest, she felt a little sorry for him.

She knew perfectly well that this student hadn't ended up in that state to show off or fool around. However dangerous and incomprehensible his actions had been, he had been trying to save someone. His intentions were good.

Professor McGonagall had always had a soft spot for students like that. Beneath her stern exterior, she was warmhearted.

But sympathy was one thing.

He still needed to understand what she was trying to teach him.

Magic was dangerous.

Advanced magic especially.

And most of all, advanced magic that you thought you understood when you had barely begun to grasp it.

At that thought, Professor McGonagall had another idea.

Rather than make him copy until he questioned the meaning of life, perhaps it would be more effective to have him face the brutal consequences of failed advanced Transfiguration firsthand.

Real failure.

A real loss of control.

To watch a transformed object twist into something horrifying before his eyes.

To make him understand that magic was not a child's toy he could mold however he pleased.

"Mr. Gu," she said.

Gavin stopped writing at once.

"Professor?"

"How advanced is your Transfiguration now?"

The question came out of nowhere.

Gavin rubbed his wrist, thought for a moment, and decided to be as conservative as possible.

"My basic Transfiguration is fairly reliable," he said. "I can manage partial transformations and size adjustments. I've made some progress with living things, but I'm not proficient yet."

Professor McGonagall looked at him.

"Show me."

Gavin nodded, picked up a blank sheet of parchment from the desk, and gave it a light tap with his Wand.

The next moment, the parchment's edge stirred. It was as though an invisible skeleton were pushing out from within. The sheet curled, folded, and took shape, sprouting a rabbit's head in the blink of an eye.

Its ears were made of paper, yet stood naturally upright. Its nose twitched faintly, and its eyes even held a lifelike glisten. The rabbit's head rested against the edge of the sheet as though it had always belonged there.

The office was silent for two seconds.

Professor McGonagall's expression barely changed.

Inside, she was astonished.

This was well beyond "good for a first-year" or even "far ahead of his peers."

He had surpassed most third-years she had taught.

More precisely—

This was a level third-years should only just be able to reach after completing the entire basic Transfiguration curriculum.

And Gavin's work was clearly among the better examples even then.

What he had shown was more than an ability to perform the technique. He had plainly developed his own understanding of "self-consistency."

That far exceeded Professor McGonagall's expectations.

The hardest part of Transfiguration had never been making something "appear." It was making its existence plausible.

The transformed thing had to hold together according to the logic of its magical construction.

"..." Professor McGonagall drew a barely perceptible breath, then said calmly, "Not bad."

Gavin smoothed the paper rabbit flat again and set it back on the desk.

"Thank you, Professor."

Professor McGonagall reconsidered her plan to let him experience the failure of advanced Transfiguration.

She had intended to raise the difficulty until Gavin stumbled at the edge of his ability, giving him a firsthand lesson in the danger of losing control.

Now the risk wasn't that he might fail.

It was that he might succeed again.

Professor McGonagall found that possibility deeply worrying.

But she had already begun. She couldn't simply pull away the ladder she had just set up.

So she pressed on.

"Try transforming one animal into another." She summoned a small white mouse. "A transformation between vertebrates."

This was fourth-year material: cross-species Transfiguration involving complex living creatures. The difficulty lay in overcoming a complex creature's self-awareness while controlling its physiology.

But Professor McGonagall no longer cared which year the textbook assigned it to. She only wanted the boy to learn, under reasonably safe and controlled conditions, that magic would not always give him a safe landing.

"Listen," she said. "The key isn't the outward appearance. It's preserving a coherent internal structure and pattern of behavior. Transforming one vertebrate into another demands an even clearer understanding of magical construction than turning an inanimate object into a living thing."

As she spoke, she quickly walked him through the main points.

The skeletal axis.

The distribution of weight.

The proportions of the limbs.

Support for the torso.

Overall coordination after the sensory organs changed position.

And, most importantly, self-consistency.

Gavin listened closely.

And the more he heard, the clearer it became.

For him, it really wasn't that difficult.

As he saw it, the hardest part of basic Transfiguration had never been the act of changing something. It came down to two things:

First, whether you understood the subject in enough detail.

Second, whether your control over magic was precise enough.

Get those two things right, and Transfiguration was essentially a matter of using magic to shape an object's appearance and the logic of its existence until the result held up under the Self-Consistency Principle Professor McGonagall always stressed.

Of course, he still didn't quite understand the Five Exceptions to Gamp's Law of Elemental Transfiguration.

The rules about food and gold in particular still seemed to leave crucial questions of logic unanswered.

But the basic framework posed little difficulty for him.

So, after listening to Professor McGonagall's explanation, he tried turning the small white mouse on the desk into a sparrow.

Its bones shrank.

Its forelimbs extended.

Its tail shortened.

Its neck lengthened.

Feathers grew under the guidance of his magic, light and thin and neatly aligned.

The sparrow landed on the corner of the desk, tilted its head, and even gave its wings a flap.

A flawless cross-species transformation.

Professor McGonagall: "..."

She stared at the sparrow for two seconds, beginning to seriously suspect that today's detention had somehow turned into an advanced private lesson.

"Not bad," she finally said, her voice even.

The problem was, this wasn't what she had wanted to see.

She had wanted Gavin to fail.

She had wanted him to trip on a higher step—safely, but memorably.

When the white mouse turned into something twisted, she would restore it and use the moment to teach him a lesson.

Instead, he hadn't stumbled at all. He looked ready to keep climbing.

Professor McGonagall had no choice but to go further.

"The Vanishing Spell," she said.

Gavin looked up.

"Professor, isn't that fifth-year material?"

"Yes," Professor McGonagall said, expressionless. "You've clearly earned it today."

For her, that was already a remarkably unrestrained show of emotion.

She raised her Wand and demonstrated the principle.

The Vanishing Spell was intricate and dangerous. It did not simply destroy something, nor did it transform it in the ordinary sense. It was closer to removing a thing from the current plane of existence.

As Gavin listened, however, his brow slowly furrowed.

"That doesn't make sense," he said.

Professor McGonagall turned to him.

"What doesn't?"

"If the Vanishing Spell exists," Gavin said, "then the Five Exceptions to Gamp's Law of Elemental Transfiguration shouldn't."

The office fell silent at once.

"Explain," Professor McGonagall said.

"If you can make something 'vanish' from existence, then you must have some way of dealing with its most fundamental state of being." Gavin thought for a moment, trying to explain the Information Conservation Principle in terms a wizard would understand. "So why not food? Why not gold? Why not magical objects? If you can make something disappear in an absolute sense, then you should also be able to bring an object into existence. Strictly speaking, the two ideas conflict in theory."

That was precisely what had always struck him as strangest about Transfiguration theory.

In a sense, the Five Exceptions said this:

Existing Transfiguration theory had not explained the most fundamental question. It had simply marked off certain things as forbidden territory.

But if the Vanishing Spell worked, it seemed to say something else:

There was no forbidden territory. At its furthest extreme, Transfiguration could turn something from "being" into "nothing."

Set side by side, the two claims plainly conflicted, and Gavin couldn't let it go.

Professor McGonagall was silent for a while.

"The usual explanation is that a vanished object becomes complete nothingness," she said.

"Then what is nothingness?" Gavin asked.

"..."

"If it truly becomes nothingness, then this isn't merely a question of the limits of ordinary Transfiguration," Gavin continued. "It means the premise behind the Five Exceptions doesn't hold at all. Because 'vanishing completely' is even harder to believe than 'conjuring food.'"

Professor McGonagall looked at him.

To be honest, she couldn't come up with an explanation in that minute that would fully satisfy even herself.

Logically, Gavin's question was sound. He had approached it from an angle she had never considered.

Gavin had the Information Conservation Principle to support his reasoning, but the wizarding world clearly hadn't discovered that theory yet. Everyone simply assumed that creating something from nothing and turning something into nothing were two different things.

Gavin was far too perceptive for a first-year student. In a few words, he had exposed an issue most wizards accepted without ever examining it.

In the end, she could only keep the situation under control for now.

"Your point is interesting," she said reluctantly.

For Professor McGonagall, that was more or less, Please stop taking this apart for a moment. I need to think.

"But the spell exists," she continued. "The Vanishing Spell is real, and you can't disprove it through logic alone. There must be some theory at work here that we haven't noticed. I'll grant you, it's a very novel line of inquiry."

Gavin thought for a moment, then nodded.

"That makes sense."

"Besides," Professor McGonagall added at once, "we're learning the Vanishing Spell right now, not finding excuses for you to skip it."

"I'm not making excuses," Gavin said. "I'm just curious."

Then he paused. Since he hadn't worked out the theory yet, he might as well try the spell himself first.

He looked down at the snail on the desk, their subject for the Vanishing Spell.

"Professor."

"What?"

"I think I've learned it."

"Gu—"

Before Professor McGonagall could finish, Gavin raised his wand.

Magic struck, and the snail on the desk gave a slight shudder.

The next second, it vanished.

Nothing remained.

The desktop was empty, as clean as if the snail had never been there.

For a moment, the only sound in the office was the fire burning in the Fireplace.

Gavin studied the empty desk, deep in thought.

"Practice before theory," he explained, looking up at the stunned Professor McGonagall. "It's actually quite common."

He paused, then added silently, The pioneers in a certain great country in the East spent a long time working that way.

Professor McGonagall: "..."

Sitting behind her desk, she felt, for the first time, the distinct exhaustion of having her entire view of the world called into question.

She had intended to use detention to teach this child that magic was dangerous.

Instead, by the second half, detention had turned into this:

A first-year had demonstrated third-year Transfiguration on the spot, casually completed fourth-year work involving a living creature, questioned the logic of the entire Transfiguration system, and then vanished a snail right in front of her.

This detention had strayed completely from her original lesson plan.

Completely.

And she still couldn't tell where, exactly, things had first gone wrong.

Professor McGonagall looked at him in silence for a long time. At last, she said just one thing:

"Mr. Gu."

"Professor?"

"I'm beginning to understand why Dumbledore asked me to keep an eye on you every Saturday."

Gavin considered that, then nodded.

"Thank you for understanding."

"That wasn't a compliment."

"Thank you anyway."

Professor McGonagall closed her eyes for a moment.

Then she decided to end tonight's lesson... No, detention.

At the very least, she would end a detention that clearly could not bear any further increase in difficulty.

"Go back," she said.

"I don't need to keep copying tonight?"

"Go back," Professor McGonagall repeated.

"Yes, Professor."

Wisely, Gavin gathered his books and quill, stood, and headed for the door. At the threshold, he glanced back at the spot where the snail had been, as though he still hadn't given up on working out how the Vanishing Spell and the Five Exceptions could coexist.

Professor McGonagall noticed.

So before Gavin made it out the door, she added one last warning:

"And don't secretly investigate the theoretical limits of the Vanishing Spell on your own."

Gavin stopped.

"Professor."

"What?"

"That instruction isn't precise enough to enforce," he said. "I might not know what counts as 'secretly.'"

"Out!"

"Yes, Professor."

Once the door closed, the office finally fell quiet.

Professor McGonagall sat alone behind her desk, staring at its empty surface and the sheet of parchment that had sprouted a rabbit's head earlier. For a long time, she didn't move.

The fire crackled softly in the Fireplace.

For the first time, she seriously considered something—

Perhaps the most dangerous thing about Gavin Gu now wasn't whether he dared to perform those dangerous experiments.

It was how quickly he learned.

So quickly that even the traditional approach of letting him make a small mistake and learn his lesson was losing its effectiveness.

At that thought, Professor McGonagall slowly raised a hand and pressed her temple.

"Merlin," she murmured. "Next Saturday, I'll just have him keep copying."

At least copying from a book wouldn't make fourth- and fifth-year lesson material vanish into thin air.