Sherlock waited until John and Lindsay had caught up to him before pushing open the potions laboratory door. John sucked in a deep breath through his nose and willed himself not to pant after their sprint from the lake. He hadn't seen Sherlock cast a spell, but he must have done, as the heavy old door swung inward in complete silence, unleashing the scents and sounds of several cauldrons bubbling within. No one was immediately in view.
Sherlock slid his wand from his sleeve into his hand and stepped into the room, every line of his body in a coil. John was only a half step behind, wand already out and pointed ahead, Lindsay at his shoulder. The laboratory was empty.
Sherlock lowered his wand and dashed to the closest cauldron. He peered inside for a moment, then began rummaging amongst the ingredients strewn across two tables.
"Nettles, lovage, chomping cabbage – these explain the burning sensations, John."
"And why the burning bitterroot helped soothe it," John said, leaning closer, attention still partially on the door, to examine the table. "And I wondered if bulbadox mightn't be in there, too."
He was puzzled. So far, the ingredients were fairly innocuous – unpleasant, to be sure, but hardly adding up to the kind of suffering he had seen. There were lionfish spines and belladonna and runespoor eggs as well, all only slightly more dangerous. Overall, it looked more like some sort of stew than a sophisticated potion.
"Here." Sherlock said, picking up a small vial and holding it up to the light.
The liquid inside was the palest blue and milky-looking, but shot through with spirals of a darker, more translucent shade.
"Is that…" Lindsay took a few steps closer.
"A Exaggeration Elixir, yeah," John said, taking the bottle from Sherlock, who allowed it with only a passing frown. "It would take whatever is in there and magnify the effects. And the duration of the symptoms. Madam Pomfrey keeps some of this around in case of dragon pox – that way a little potion can be spread around to all the students. I wonder if this is from her cupboards. It's a controlled substance, have to be over 17 to buy it. And it doesn't come cheap."
Lindsay returned her eyes to the door, keeping her wand partially raised. "Anything lethal mixed in?"
John was still examining the ingredients, but Sherlock answered. "No, not even anything that could be lethal in larger doses. Someone was thorough."
"But why didn't Scarpin's Revealer spell work?" John asked, bending over the ingredients once more. "Hang on, here's an empty bag. Sherlock, any idea what was in this?"
He had just raised his head when a shift from Lindsay indicated they were no longer alone. His wand was in dueling position before he recognized the figure in the doorway.
"It's leopard's bane, relative of wolf's bane, most commonly found in Afghanistan. Professor Sprout just started growing it this year," said Victor Trevor, walking into the room with a casual calm that seemed to ignore the fact he had two wands trained on him. "The mashed leaves are a binding agent that will hold against all but the most powerful spells. Quite useful, really. I can think of dozens of applications."
John glanced at Sherlock, expecting a witty retort, but instead found him staring at Victor with – was that betrayal in his eyes? It wasn't an emotion he expected from Sherlock, but the 15-year-old seemed genuinely confused.
"So I take it one of those applications was poisoning everyone at Hogwarts?" John asked.
"Oh, not everyone," said Victor, smiling almost condescendingly. "Just the ones who helped land my uncle in Azkaban. And poison is such a strong word. I've given them a dose of a potion. It's not lethal. I made sure."
"Your uncle landed himself in Azkaban," John snapped.
Victor's face flushed. "He didn't have a choice! It was join up or get all of us killed. Voldemort knew he was one of the best spell creators in the country. Uncle Roget did what he had to do, and he got sent to prison for it."
They needed to block his exit. John made eye contact with Lindsay, was already moving carefully toward the door, keeping herself in Victor's periphery.
"But –" Sherlock had found his voice again, strained and unnatural, but functioning. "Consider the alternative. You would rather the rest of those men were still at liberty?"
"I would rather have my uncle back with his family," Victor snapped.
"That's not logical," Sherlock said, stepping closer to the Ravenclaw, a hint of accusation in his voice. "You always said too many people make the mistake of letting emotion keep them from the bigger picture."
Victor shrugged. "And I guess I'm one of them. Sorry, Sherlock. Here's another life lesson for you: people never live up to the morals they mouth."
"What was your plan? Poison all the DA members? Didn't you think people would make the connection? What was next? Get to McGonagall? Get to Potter, somehow?" Sherlock asked. "This was hardly thought out, was it?"
Victor's chin jutted out. "I didn't care if people made the connection. I wanted people to understand that being the winner doesn't mean escaping unscathed."
"Oh, we learned that lesson without your help, thank you," John said.
Victor curled his lip at him, but it was Sherlock who spoke, his voice still strangely subdued. "You know we're going to have to tell them, Victor. What does this mean for you? Expulsion?" A crack of heat was in his voice as he moved forward. "Perhaps a stint in Azkaban yourself? You didn't even bother to consider repercussions, did you? Didn't think that anyone in this school was clever enough to get to the truth."
"I'd expected to get farther along, possibly have more bargaining leverage," said Victor, returning to his cool, collected tone. "But really, does it matter? Two of you were on my hit list, regardless."
John instinctively ducked when Sherlock did, letting Victor's spell sail above his head and crash into a shelf. A jar of pufferfish eyes exploded.
Lindsay shot a spell from behind Victor, but he pivoted to the right and avoided it. John aimed around all three of them and magicked the door closed. Victor rolled his eyes.
"Oh dear, I'm trapped," he said mockingly. "There's no way I can ever leave this room. Mudblood fool."
Lindsay aimed a Stunner at him so powerful John could hear the air crackle around it as it crashed into the stone wall. Victor shot a spell in return, which Lindsay ducked. John took a moment to look around. Sherlock was shuffling toward the cauldrons on his knees while Victor was engaged with Lindsay. Lindsay and Victor were exchanging and parrying spells at lightning speed. Victor fought with the trained grace and rhythm of a duelist, keeping his body turned so he could turn at any moment to face an opponent from behind. John scrambled forward to cover Sherlock's progress and sent a stinging jinx at Victor. It ruffled his robe, but did not hit him.
Annoyed, Victor slashed a spell over his shoulder and turned to block one from Lindsay. John ducked and threw another Stunner. A shield charm rebounded it toward him, but it careened into the table instead, making the cauldrons wobble. The bolts of light dazzled his eyes as the duel continued. Victor was holding his own, blocking and retaliating with a panache John could almost envy. And his own skill was returning. He'd managed to slip two spells past Victor's guard, causing the unsightly swelling on the left side of Victor's face, and a dust cloud that had given John the split second he needed to get close enough to get into clear space. He was aiming to simply tackle the Ravenclaw, but the boy Vanished the dust and turned a particularly strong spell onto John, which he dove to the right to avoid.
"Stop."
It was Sherlock's voice, deeper than usual and positively intimidating in its authoritative chill. He was standing by the cauldrons, his wand tip dripping. Something flickered across Victor's fierce expression.
"Sherlock –" he said warningly.
"You think I couldn't figure out how the system works?" The boy smirked. "You shoot a stabbing jinx of some sort with the wand tip dipped in the substance. It creates a hole like a creature's stinger, and the potion is cleanly administered. Excellent idea. The problem with this type of administration, though, is that anyone could do it."
He flicked his wand and sent a spell whizzing directly between Lindsay and Victor. They both jumped a bit to the side.
"Now listen, Victor," Sherlock continued, dipping his wand back into the cauldron and glancing with some interest at the smoking divot in the wall. "There's nothing I can do to keep you from whatever punishment the Wizengamot decides on. I might be able to help your uncle, though, if you'll put down your wand and go quietly."
"Your negotiating skills need some work, Holmes," Victor said, grinning suddenly. "You're better suited to the world of theories." He flicked his wand to his left and a rope twined around Lindsay's torso.
Victor tugged it toward himself, positioning Lindsay as a shield between himself and Sherlock, over her squirming protests. John caught Lindsay's eye for a split-second, and she nodded. John made a low tackle that caught Victor's knees and threw all three of them to the ground. A swift punch to the jaw drove Victor's head back and into the stone floor with a rather sickening crack. His grip on his wand slackened for a moment, and John pulled it out of his hand. The boy reared up, and brought his knee into John's stomach. The air rushed out of his lungs painfully, and he crumpled. Victor shoved him aside, scrambling for his wand. John gathered himself with one gulp of air, and Victor's face collided with his fist. This time he relaxed onto the stone floor, apparently out cold.
John reached for his own wand and severed the cord holding Lindsay. He staggered to his feet and held out a hand to her.
"How's that for a dramatic rescue?"
The larger Zhacan cub seemed to be developing quite an attachment to him. John held it under his robes cautiously, as he maneuvered the corridors to the Transfiguration study. It snuggled closer to his cardigan and released a noise John assumed was the equivalent of purring.
"You'll have friends of your own kind soon," he told it.
The Doctor had convinced the Zhacan to leave with him, but for extra insurance, the cubs were coming to the TARDIS via John and Lindsay. Sherlock had no further interest in the creatures now that the mystery was solved, and had stayed in the castle to discuss Victor's situation with Professor McGonagall after they'd delivered the potion components to Madam Pomfrey. He'd agreed to meet them in the study when he was done to see the Doctor off, John assumed because he was curious to see how the spaceship was to take off or land from within the study.
"It's almost a shame they can't stay," Lindsay said, tickling the smaller one under the chin as they approached the door, where the Doctor was waiting. "They'd make great pets."
"Yeah, except for the fact no other animal would be safe around them," John said incredulously. "I don't want a pet that can almost take down a thestral."
"Alright," the Doctor said, rubbing his hands together. "Mummy's going to be joining us through the window. In fact, she's probably hanging around outside now. So let's get this done."
He opened the circular lock and rearranged the various curves and circles until there was an audible click and the door swung open. John let the little Zhacan down and herded it into the room on foot. The Doctor was already unlocking the TARDIS.
"I thought you said the TARDIS wasn't working properly," Lindsay said. "Are you sure you'll be able to make it back?"
The Doctor grinned. "Oh, I gave my word, never fear. I told Professor McGonagall she may need to cover classes for me for a few days, just in case I'm not as precise about getting back as I'd like to be."
"What if you waited till the weekend?" Lindsay suggested. "Then you'd have a buffer."
"I think you're trying to ask another question in all this, Miss Lovejoy," the Doctor said, smiling.
"She's trying to say that she'd love a ride in your space-traveling phonebox," Sherlock said from the doorway.
"And hello to you, to," John said by way of a remonstrance.
"I'm sorry, Lindsay, but I couldn't risk you missing your classes. What would your parents say?"
"That it's a valuable opportunity?" Lindsay suggested hopefully. "No, who am I kidding? They'd be horrified."
"Precisely. And you're not quite of age yet to make the decision on your own."
"Only a few more days."
"I'm sorry," the Doctor said firmly, leaning out to open the window. "Maybe at the end of term. Like an end-of-school road trip."
"Really?" Lindsay asked, eyes shining. John found himself almost jealous.
"Sure, if you want to come. Any of you," the Doctor said, his eyes lingering reluctantly on Sherlock. "It's the least I can do for you keeping my secret from the rest of the school."
The Zhacan climbed in through the window, eyeing all of them with distrust. The Doctor motioned it into the TARDIS door and shooed the cubs along with it.
"Well, I guess I'd better get going. With any luck, I'll be back from Zhactarm by tea time. If not, I'll be seeing you soon."
He gave Lindsay a hug, shook hands with John, and offered one to Sherlock with a rather uncertain air. The Ravenclaw took it briefly.
"You're legitimately mad," he said. "I hope you know that."
"Oh, I should hope so. All the best people are. Even you, I fancy," the Doctor responded.
He leapt into the TARDIS with one final wave and closed the door. The rusty sound John had triggered the other night came again, and the light atop the box began glowing. The phonebox was literally fading away, something John thought ruefully shouldn't be surprising after 7 years at Hogwarts. A glance at Lindsay's face, though, made him pause. She looked rather desperately disappointed.
The noise stopped. The box rematerialized. John exchanged glances with Sherlock and Lindsay, but neither face held any answers. The door swung open and the Doctor poked his head out.
"Or, maybe, just one adventure now?"
Fin.
To all my readers, thank you for following along. This story has been such fun to write!