Regulus sat down, hands on his knees, posture correct.
McGonagall pushed the parchment aside to clear a stretch of desk, folded her hands on it, and looked at him.
"Go on, Mr. Black. What's your question?"
"It concerns permanent transfiguration, Professor."
Her eyebrows shifted a fraction and something flickered behind her eyes.
No surprise showed on her face. Nothing young Black asked would surprise her. But this particular question meant he hadn't spent the past weeks idle.
She nodded for him to continue.
"Once an object has been transfigured, it carries a standing inclination to return to its original form," he said without preamble. "The more complete its structure, the stronger that pull. My understanding is that sustaining a transfiguration is, at bottom, using magic to continuously suppress that return."
His tone stayed that of a student seeking instruction. "What I'd like to ask is where that inclination originates. Whether it can be eliminated at the root. And whether eliminating it produces Permanent Transfiguration."
She took her hands off the desk when he finished, studying him with something like approval.
A serious question, one no textbook would answer and no second year had business worrying about, and yet coming from him it didn't strike her as out of place.
His grasp of Transfiguration had always run deeper than his peers', reaching for essentials. She'd known that since the matchstick and the linden.
Permanent Transfiguration was hardly rarefied territory for her, and for this child it wasn't wholly beyond reach either.
Only nobody had taught it to him yet, and the Restricted Section held little on the subject.
That he'd arrived at the step on his own was the rare part.
Plenty of wizards drilled Transfiguration for a lifetime and treated it as a trade, never once asking what it fundamentally was.
She straightened in her chair. The question deserved a proper answer.
"The inclination to return," she began slowly, her tone still severe but carrying something of private conversation rather than lecture, "comes from the transfigured object's conviction about what it truly is."
He listened, deferential and quiet.
"Turn a desk into a pig and you have altered its outward form. Its conviction regarding its own nature you have not touched at all. The new shape is imposed from outside, while its inner true form remains intact, still a desk. The two contradict each other, and so the transfigured thing perpetually strains back toward the shape it believes in. What you sustain is never the new form. What you are actually sustaining is the conflict between its interior and your external force."
He nodded.
Not difficult to follow. What she described and what he'd felt in class were the same thing.
That backward drag came from the slate's conviction that it was stone.
Outward form could change; the inner true form could not. There lay the contradiction, and out of it came the pull.
He'd circled something like this before without ever pinning words to it.
Conviction. True form. Turning them over, yes. That was how it worked.
She waited a moment, and when no question came, nodded again. "There are two roads to eliminating that inclination."
He focused.
"The first is the one nearly all transfiguration travels. Suppression. If the caster's magic and will are strong enough, the old true form can be held down indefinitely, never permitted to surface. But this is only suppression, not alteration. Suppress it for a lifetime and it stays down for a lifetime, and the instant you release it, back it goes. That road has no destination, because the resistance inside is present from beginning to end. You have merely prevented it from acting."
He nodded again.
Her resistance was his contradiction.
Satisfaction crossed her eyes when she saw he'd followed, and she went on.
"The other road runs deeper. Rather than pressing the old true form down, you change it, so that the transfigured thing accepts the new shape as an answer to what it is. The new form is no longer something added from outside. It becomes part of the thing itself. Once it holds that conviction, the inclination to return has nothing left to spring from. It no longer wants to go anywhere else, because it is convinced that this is how it ought to be. At that point nothing needs sustaining. That is Permanent Transfiguration in the true sense."
"The first road tests how strong your magic is. The second tests whether you can rewrite the true form of a thing."
"Changing a thing's outward shape is easy. Changing its true form is extraordinarily hard." She met his eyes, her tone weighting. "Transfiguration at that level belongs to another order entirely."
He kept the same respectful expression while his thoughts ran on beneath it.
The first road he understood, because it was what he'd been doing all along. Magic pressing down, will holding it up, the shape pinned in place so it couldn't turn over.
The second road had never occurred to him.
Everything he'd imagined lived on the first road. Stronger magic. More enduring suppression. Or pouring more of the caster's will inside to hold the old true form flat.
Suppression versus reshaping. He'd spent all his turning-over on how to suppress more thoroughly.
Spatial Transfiguration had gone the same way, magic thrown against the elasticity of space until McGonagall demonstrated by making the elasticity itself the target, and only then had it clicked.
What he'd taken to be bedrock, untouchable, could become the object of transfiguration.
Push reason to its limit and it jams in a dead corner. Magic goes around it.
The same failing again.
Then again, he hadn't started on Permanent Transfiguration in earnest. No direction fixed yet, only scouting one.
Strictly speaking, not another fall. At most a near miss.
Reading his face, she seemed to work out what was happening, and a note of displeasure entered her voice. "Mr. Black, I expected you to have reached that yourself. Did Spatial Transfiguration not already teach you as much?"
He inclined his head, sincere. "You're right, Professor. I should have approached it from another angle. Thank you for pointing it out."
A short breath went out through her nose. She let it drop, her expression easing.
He drew his thoughts back in.
The correction was fair, but this hadn't been tunnel vision, and besides, what he actually wanted wasn't how Permanent Transfiguration was performed.
All of it was groundwork. The real question came after.
The Decomposition Curse.
Take an organic living body and unmake it at the level of existence, break it down to its most basic constituent units.
At that point the thing decomposed retains no true form. It is no longer itself.
By what she'd just laid out, the inclination to return is rooted in that true form.
So if a thing were broken down until it held no conviction whatsoever about what it was, with no original left to speak of, would it still have any direction to return toward?
And if, after decomposition and before those basic units re-formed, a transfiguration were applied inside that window, would the returning force be bypassed entirely?
Would the new shape, having nowhere it cared to return to, fix itself permanently?
Joining decomposition to shaping. That was the answer he wanted.
He couldn't ask it outright.
Too specific. Specific down to decomposition, which amounted to confessing that he possessed such a method.
McGonagall was Britain's foremost master of Transfiguration after Dumbledore, her grasp of existence and form running to depths he couldn't measure.
One mention of decomposing existence and she'd work backward from it.
Where did the boy get this? Has he seen such magic? Worse, can he do it?
Even short of the whole picture, close enough would be plenty.
He didn't fear her knowing. But not knowing was better still.
The Decomposition Curse was the thing he kept at the bottom of the trunk, and by any reckoning it was not respectable magic. Better kept from her.
So the question needed rephrasing, and he'd planned for that.
One question could be split apart, tucked into separate conversations, resolved a piece at a time.
Today only Transfiguration. However deep it ran, it stayed pure theory.
He raised his eyes. "You said the inclination to return is rooted in the object's conviction about its own true nature."
His posture stayed correct, his tone still that of a student. "Then in theory, I wonder whether that conviction, besides being altered, might also be stripped away."
Her gaze rested on his face a moment, approval showing, and she gave a small nod.
"If a transfigured object had its conviction about itself removed entirely," he continued, "and fell into a state where it was no longer defined as any determinate thing... would it then have no direction of return at all, because there is no original to return to? And if a new form were conferred on it in that state, could that form hold permanently, having no inclination pulling against it?"
Only whether it was possible in theory. Never how.
After the Decomposition Curse took a target apart, the basic units remained. Their former mode of existence scattered, no longer the thing they had been, but the material hadn't been lost.
Between no longer the original thing and dispersed into useless basic units there ought, in theory, to be an exceedingly narrow window.
In that span the units hadn't yet dissipated and hadn't yet recombined. They were nothing at all. They were only still there.
What he truly wanted to know sat underneath all of it. Decomposition plus transfiguration. Was there anything in it?