The previous night's events rippled outward, though not in the direction Regulus had expected.
He'd underestimated how badly young wizards wanted a shortcut.
Especially those from families with adult wizards in the house. Half-bloods, mostly, or pure-blood families only a few generations deep. They had enough exposure to the magical world to know a little, but not enough to know better.
They knew Protego was difficult. They knew plenty of grown wizards in their own families couldn't cast it properly.
So what Regulus had done last night lit something in them. A hunger. As if they'd stumbled onto a secret no one had told them about.
So that's how you learn Protego?
You can learn it like that?
Someone can just point a wand and make a first-year produce a full shield?
My dad can't cast Protego because nobody ever helped him?
They didn't think deeper. Couldn't, really. No one skilled enough had told them the truth: that what they'd witnessed was a trick of the moment, a taste of the real thing. Mastering the spell still required grinding through it yourself.
All they saw was the result.
So overnight, the upper-years who could cast a proper Protego became minor celebrities.
In corridors, in common rooms, younger students crowded around them with the same question.
"Can you teach me the way Black did?"
"Is there some trick to Protego?"
The reactions varied.
Some were honest. "I can't do that. It probably takes a unique technique, or a level of skill I don't have."
Others didn't know any better either, but after being asked enough times, started hedging.
A fifth-year Gryffindor boy lounged on a common room sofa, surrounded by a cluster of first-years, and said with practiced authority, "Well... Black's method isn't something just anyone can pull off. It requires, mm, a specialized casting technique. You lot aren't ready. Work on fundamentals first."
He sounded perfectly serious. He had no idea what he was talking about. The first-years nodded along anyway.
A fourth-year Ravenclaw girl offered something closer to substance, though she dropped her voice to a conspiratorial hush. "The real secret to Protego is... don't tell anyone, all right? You have to picture someone you absolutely can't stand. Then take that feeling of not wanting them anywhere near you and amplify it."
She glanced left and right, then added, "Best if you get them to stand in front of you and confess their feelings."
Several first-year girls lit up. "Really?"
"Of course." The older girl nodded with complete conviction.
Nearby, a boy who knew the real story rolled his eyes. He was the one she'd rejected.
Back then, she'd come to him looking all bashful and said, "I'd say yes, but you haven't actually asked me out yet."
He'd been so wound up he couldn't sleep that night.
The next evening he'd put on fresh robes, brought flowers, and confessed his feelings in front of the entire common room.
She'd shot him down in front of everyone.
Now, hearing her dispense this wisdom with a straight face, the pieces finally clicked.
Not that he cared anymore. He'd just been young and stupid.
As for the old pure-blood families, they stayed out of the frenzy. They had people to ask.
Plenty of owls had gone out the night before. By morning, the replies had come back.
The tone from home wasn't particularly gentle.
Most letters told them to focus on fundamentals and stop chasing nonsense. A line or two at the end, almost as an afterthought: stay on good terms with the Black heir, but don't be obvious about it. Don't make yourself a nuisance.
One sixth-year boy read his letter and sighed.
The family acknowledged that the technique was impressive, but said it wasn't suited for ordinary young wizards. You've seen it, now move on. Practice what you're supposed to practice.
He folded the letter away and didn't mention it to anyone.
Over in Gryffindor, James Potter had heard about the previous night.
He knew Protego, of course. He'd been able to cast it since last term. Whether that came from natural aptitude for dueling magic or from throwing himself into practice after Regulus had flattened him a few times was hard to say.
Either way, he could produce it, but only just. Bare minimum.
Last term, that had been enough to block a few of Sirius's spells. This term, something was off.
Any spell Sirius threw shattered his shield.
Once could be a fluke. Twice, bad luck. Three times was a pattern.
James had been sitting on the question for a while, never quite asking it.
Now, hearing about what Regulus had done, a thought surfaced.
History of Magic. Professor Binns droned on about something. Nobody listened.
James nudged Sirius. Sirius had been staring into space and startled at the jab.
Sirius frowned. "Do what?"
James leaned closer, dropping his voice, though not nearly enough. "You know, that thing. You improved so much over the holidays. Can you do that too? The point-your-wand-and-teach thing?"
Several students nearby perked up. One pretended to flip a page. Another studied the ceiling with sudden fascination. Every ear in the vicinity drifted their way.
Sirius's expression froze. His mouth opened, reaching for words, but whatever he'd been about to say died before it left his throat.
James was comparing him to Regulus. Assuming that whatever Regulus could do, he could do too.
He knew exactly how far ahead Regulus was. That kind of gap wasn't something you closed by improving quickly. He'd spent a month getting hammered by Hawke over the holidays, then another month on different training. Coming back, sure, he could pull away from James.
But compared to Regulus...
It wasn't even close.
How was he supposed to say that? My brother's so far beyond me that what he does, I can't? Or maybe, There's no secret Black family magic. Regulus is just that much of a freak?
His expression shifted through several things before settling on irritation. "Pay attention to class."
James blinked, then shrugged. He figured Sirius just didn't want to talk about it with so many people around. He'd ask again back in the dormitory.
A few seats away, Lily's ears had pricked up. She watched the exchange, eyes blinking once, twice. Whatever she was thinking, she kept it to herself.
The ripple reached the professors too. Flitwick got cornered by a pack of Ravenclaws.
"Professor, how did Black do that with Protego?"
"What's the principle behind it?"
"Can we learn it?"
Flitwick stood atop his stack of books, smiling and shaking his head.
"It's a very advanced technique. Put simply, the caster uses their own magic to guide the other person's, letting them feel what the spell is supposed to be before they can produce it themselves. It's not a shortcut. It's a form of illumination."
One student pressed further. "Could we be illuminated too?"
Flitwick's eyes twinkled. "You'd need someone brilliant enough to guide you. If you want that kind of illumination, first find someone that brilliant."
The students exchanged glances and dropped it.
McGonagall was less gentle about it. A few lower-year Gryffindors barely got the question out before she cut them off.
"Protego? You haven't even mastered basic Transfiguration. What are you doing thinking about Protego? Go practice your matchstick-to-needle a hundred more times!"
In Professor Sprout's greenhouse, the atmosphere was warmer, but the refusal came just as fast.
"No."
Regulus stood before her, hadn't even finished his second sentence, and was already shut down.
The Professor was repotting a Mandrake, head bent over her work.
He tried a different angle. "Professor, I only want to study the magical properties of the Whomping Willow."
Sprout looked up. "Study? With what?"
"My eyes. Magical perception." He held her gaze. "No touching. No harm."
She studied him for a moment, then sighed and set down her tools.
"Mr. Black, do you know how rare a Whomping Willow is?"
He shook his head, though he already knew.
Sprout walked to the window and pointed at the distant tree, still swaying of its own accord.
"That one is over two hundred years old. Do you know why it was planted there?"
He considered. "To guard the entrance to the Shack?"
Sprout shook her head. "The Shack didn't exist yet."
She didn't elaborate. She turned back to face him.
"I planted another one myself. A seedling, thirty years ago. It's only just left the seedling stage. Nowhere near maturity."
She went on. "Whomping Willows have an extremely long growth cycle. Thirty years as a seedling, another thirty in the growth phase, then it finally enters its stable period. Sixty years from planting to maturity."
"So in all of Britain, there are exactly two Whomping Willows worth mentioning. One here at Hogwarts. One still growing under my care."
Regulus was quiet a moment. "Can they be purchased?"
Sprout shook her head. "There's nowhere to buy one. Seedlings turn up on the black market occasionally, five to eight thousand Galleons each. But the survival rate is abysmal. What you'd bring home would almost certainly die. A mature specimen has a price in theory, but no one would sell."
He did the math.
Eight thousand Galleons. A single Mandrake ran a hundred and fifty. Twenty of them cost three thousand. Eight thousand would buy over fifty Mandrakes.
Expensive, but not impossible.
The Mandrake investment had yielded the Decomposition Curse, something he could use as a trump card. Even if a Whomping Willow cost several times more, developing a new spell from it would justify the price.
But eight thousand Galleons for a seedling that would probably die? Not worth it.
"What about wild ones?" he asked. "Do you know where wild Whomping Willows grow?"
Sprout gave him a look. "Not giving up?"
He ducked his head, managing to look faintly sheepish.
"The Bulgarian Magical Reserve has a few," she said. "Wild, mature specimens. The edges of the Romanian Dragon Sanctuary too, mixed in near the dragon habitats. There's an old estate in southern France that supposedly has one in a private collection. And deep in the Black Forest in Germany, there are rumored to be some, though nobody's confirmed it."
She watched him. "What, planning a trip abroad?"
"Just asking."
Sprout held his gaze a moment longer, then a smile broke across her face. "I think I can guess what you're after."
He looked up but said nothing.
She walked back to her workbench, picked up a potted Mandrake seedling, and turned it in her hands as she spoke.
"The magical properties of a Whomping Willow are quite unusual. When it strikes, the force doesn't come from brute strength. It comes from conduction. The impact travels along magical channels into the target's interior and triggers a resonance there. Hit a stone with one of its branches, and on the outside you'll see just a surface mark. Inside, it may already be shattered."
Regulus turned the two words over in his mind. Resonance and conduction.
Then he thought of the Reductor Curse. The standard version worked by blasting from the outside in, forcing the target apart.
The Whomping Willow's destruction was the opposite. It collapsed things from the inside out.
Exactly what he needed.
The Decomposition Curse handled living things. The Whomping Willow's principle handled hard matter.
One targeted life. The other targeted substance.
A perfect complement.
He pressed for details. How did the magic conduct? How was the resonance triggered? How did the effect differ across types of material?
Sprout answered everything. Thoroughly, without holding back.
When she finished, she looked at him. "Enough?"
Regulus dipped his head, gratitude clear in his voice. "More than enough. Thank you, Professor."
Sprout waved him off. "Go on, then. But remember, don't even think about the one on the castle grounds. That tree isn't mine. It belongs to Hogwarts."
A faint smile. "I promise I won't touch it."
He turned to leave. Sprout called after him.
"Mr. Black."
He looked back.
Her expression was serious now. "If you ever do find a Whomping Willow, and you develop something from it, tell me."
His tone matched hers, earnest and certain. "You have my word."
He pushed through the door and was gone.
Inside the greenhouse, Sprout watched the door close and shook her head.
She had a fair idea what the boy was trying to do. She wasn't going to stop him.
If he figured it out, that was his talent.
If he didn't, that was his business.