Regulus lowered his head slightly, respectful. "The Venomous Tentacula's magic doesn't follow fixed channels. It diffuses and permeates. Completely different logic from the Whomping Willow."
Sprout nodded, tapping her fingers lightly on the watering can beside her. "One slow, one fast. One quiet, one violent."
Her brown eyes settled on him, a hint of mischief at the corner of her mouth. "The Tentacula's paralysis. Planning to study that too?"
"Not for now," Regulus said, shaking his head. "Only observing."
He'd stayed behind to honor a promise.
The Whomping Willow's magical properties and tendencies had come from Professor Sprout. Last year she'd given him two words: conduction and oscillation. The Disintegration Curse followed from there.
He was grateful to her.
And she'd said, if the day came when he found a Whomping Willow and discovered something, to tell her.
"Professor, the Whomping Willow research produced results."
Sprout's hand paused mid-wipe on her apron.
She looked at him. Her eyes brightened.
She hung the last pair of shears on the wall hook, pulled over a stool, and sat down, patting the one beside her. "Sit. Tell me."
Regulus sat and picked up a piece of dead vine tip left over from the trimming, placing it on the bench between them.
He laid out the research path in brief.
Starting from the conduction and oscillation she'd taught him, he'd used Verdant magic to establish a connection with the Whomping Willow, perceiving its full attack mechanism at close range and replicating the oscillatory conduction model.
"The key is oscillation stacking. Each strike the Willow delivers generates vibrations that automatically seek out fractures left by the previous impact, following the cracks deeper. Each iteration doubles in efficiency. I extracted that logic and built a spell from it."
He raised his wand and murmured the incantation.
A beam shot from the tip, narrow, its edges carrying a fine tremor, visibly unstable. It struck the dead vine tip.
The surface held for an instant. Then fractures bloomed across it, deepening and spreading in rapid succession. The entire piece collapsed into a mound of fine debris on the bench.
No sound. No flash. It crumbled in silence.
Sprout stared at the remains. She reached out, pinched a bit between her fingers, and rubbed them together, feeling the texture.
"Shattered from within." Her voice was soft, her gaze appreciative. "Consistent with the effect of a Willow branch strike, but you've made it controllable."
A trace of a smile reached Regulus's eyes. He nodded.
The professor was quiet for a moment, the crushed residue sitting in her palm. Then she said something he hadn't anticipated.
"This would be wonderful for loosening soil."
Regulus's mouth twitched.
She either didn't notice his expression or noticed and didn't care, continuing on her own track.
"That patch behind the greenhouse. Three feet down is a layer of compacted clay. Every spring I spend three days breaking it up with magic, layer by layer. My arms ache for a week."
She tipped the dust from her palm onto the edge of the bench and gathered it with her fingertips. "If this could break up the compacted layer from the inside..."
She turned to him, eyes full of warmth and a weighty sort of expectation.
What sat before her was not a second-year who could develop his own spells. What sat before her was a particularly good shovel.
The corner of Regulus's eye twitched.
The same creation, and he and his father thought about scaling it up. The professor thought about scaling it down.
Father and son saw weapons potential... Professor Sprout saw agricultural potential.
He gathered himself and nodded with due respect. "You're right, Professor. It's perfectly suited for loosening soil. Lower the intensity, limit the range, break up the clay without damaging root systems. Entirely doable."
The professor slapped her knee in satisfaction, regarding him with even greater approval.
"Come help me till when spring arrives."
Regulus straightened on his stool, his expression close to delighted, his voice carrying unmistakable eagerness. "No problem, Professor."
She laughed, standing and brushing dirt from her apron. "Wait here a moment."
She turned and walked deeper into the greenhouse, crouching before two rows of planting troughs full of Bouncing Bulbs. Her fingers sank into the potting soil to test the moisture, then she turned over a few leaves to check the undersides, pulled out her trowel, and loosened the topsoil.
Regulus sat on his stool and waited.
Before long the professor came back, wiping her hands on her apron.
She sat down again, her gaze settling on the pile of debris. Her tone remained gentle. "Mr. Black, what you learned from the Whomping Willow is how to shatter. The Willow doesn't know what it's hitting. A branch comes down, strikes whatever it touches. Your spell is different. You have a target. You choose what to shatter."
"A person who can choose what to shatter can also choose what not to. That's the difference between you and a tree."
Regulus met her gaze and nodded with care. "I understand, Professor."
Destruction was a capability. Choosing not to destroy was one too.
He thought of what Professor Slughorn had told him: stay away from the irreversible things.
The professors at Hogwarts were each guiding him in their own way. None of them forced him down any particular path or grabbed his arm and said you must do it this way.
Sprout didn't press the point. She stood and patted the dirt from her apron. "Remember it. That's enough."
The conversation wound down, and Regulus's gaze drifted unconsciously toward the depths of the greenhouse.
In the far corner stood a glass cabinet under a temperature-regulating charm, silent and still. A thin mist clung to the inside of the glass, obscuring whatever lay within.
But he knew what was in there. The Sunlight Ebony Bush.
A shrub less than thirty centimeters tall, branches black as charcoal, leaves pure white, golden threads of light flowing through its veins.
The only specimen left at Hogwarts, planted three hundred years ago by a Ravenclaw headmaster.
Sprout followed his gaze, then looked back at him, her tone airy. "It's still there."
Regulus was still looking. Honestly, he coveted it.
This was nothing like the Whomping Willow.
Rare as Willows were, they at least had known habitats. Bulgaria had them. Romania had them. With enough money, resources, and favors, you could acquire one.
The Sunlight Ebony Bush couldn't exist in the wild, not really. Its growing conditions were too exacting. You couldn't give it the right soil and temperature and expect it to live. It needed a quality inherent to the place itself.
This wasn't something that could be obtained. The last specimen in all of Britain sat under that glass dome, where it had lived for three hundred years.
In all of Europe, you could probably count the surviving specimens on one hand.
Sprout watched him. "You're not ready."
Regulus pulled his gaze back and lowered his head. "I know."
She studied him a while longer.
She knew the boy hadn't given up. She'd seen it the last time he visited. He wanted to touch it, but she could also tell he'd held himself back.
Another term had passed, and his attitude was the same.
She shook her head and said nothing more.
Regulus exhaled softly and tucked the longing away. The professor was right. He wasn't ready.
Then he looked up and steered the conversation back. "Professor, there's something I'd like your help with."
Sprout settled back onto her stool. "Go on."
Regulus cleared his throat. "During the Whomping Willow research, one specimen was damaged."
Her expression shifted. Her lips pressed together, a flash of pain in her eyes, her voice sharpening with urgency. "How badly?"
"Excessive magical extraction. The circuitry nearly shut down." Regulus kept his eyes low, looking suitably abashed.
Then he picked up speed. "I restarted the circulation with verdant magic and cleared the root absorption channels. It's recovering, but slowly."
He finished with: "The branch tips have started budding again, and the coloring along the scar margins is deepening. It's alive, but far from healthy. I was hoping you could take a look, see if there's a way to accelerate the recovery."
Sprout drew a long breath. "A mature Whomping Willow. Do you know how many years it takes to grow a mature Whomping Willow?"
Regulus dipped his head further, his tone even more deferential than before, edging into meekness. He knew she wasn't blaming him, and couldn't. She was grieving for the tree.
"You've told us. Thirty years as a sapling, thirty years of growth."
"Where is it from?"
"The Bulgarian Magical Reserve."
Sprout's fingers tapped twice against her knee.
A Whomping Willow from the Bulgarian Magical Reserve. That wasn't a matter of sixty years.
The wild specimens there had documented histories reaching back to the twelfth century. In the valleys of the Balkan mountains, trees several centuries old were far from uncommon.
She took another long breath and settled herself.
She wasn't blaming Regulus. The tree had been procured by the Black family, procured specifically for research.
That Orion Black was willing to provide resources of that caliber as experimental material for his son was the Blacks' business.
Research meant losses. Magical plant studies especially. In decades of teaching she'd watched countless students ruin their materials.
But a centuries-old specimen...
She was quiet for a moment, then asked, "Where is it?"
Regulus maintained his meekness. "Cornwall. My family's plantation."
The professor glanced at him.
She knew about the Black plantation in Cornwall. In British magical botany circles, it was a significant asset. From Mandrakes to other ingredients, the estate maintained stable yields and had been in operation for at least two hundred years.
But Whomping Willows growing there? Her professional curiosity sparked. "Two of them?"
"Two. The healthy one is untouched. The damaged one is the one I extracted magic from."
Another pang of grief, but she recovered quickly into professional mode.
One damaged mature Whomping Willow alongside a healthy specimen meant the magical differences between the two states could be compared directly. That had immediate research value.
And the damaged tree, its circulation sustained by verdant magic at a bare minimum, requiring external intervention to recover, was virtually unprecedented in the history of magical plant care.
It could be done, certainly. But almost no one had ever faced this situation.
Mature Whomping Willows were too rare. Who would drain one to the point of shutdown?
And yet here one was, in Cornwall.
She was the foremost authority on magical plants in Britain. A case like this was impossible to resist, let alone refuse.
"This weekend. Saturday morning I have greenhouse work. The afternoon is free." She stood, decision in her voice. "Are you picking me up, or shall I go myself?"
Regulus rose as well. "I'll come for you. Saturday afternoon, two o'clock, at the greenhouse door."
Sprout nodded, then pointed a finger at him, its tip still caked with dirt, her tone carrying a note of exasperation. "Mr. Black, next time, before you start your research, consider whether you can manage to waste one fewer tree."
Regulus's mouth curved slightly. "I'll try."
The professor huffed, plainly unconvinced, but let it go. She turned and walked back into the depths of the greenhouse, crouching before a drooping Bouncing Bulb and getting on with her work.
Regulus stepped out of the greenhouse and walked toward the castle along the stones.