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The beaker smashed satisfyingly against the lab's wall. Severus turned, unaware that he was muttering aloud to himself.
"It must be perfect…belladonna's fickle, fast acting. The first bezoar will absorb any poison he hasn't metabolized, but…" His eyes skimmed the shelves of ingredients, fingers twitching as though ticking through arithmantic calculations.
First things first: counteract the effects of the poison. With no way of knowing how many deadly berries consumed, Severus didn't dare risk underestimating the threat. Atropa Belladona wasn't called 'Deadly Nightshade' for nothing. The berry's alkaloids were already blocking the acetylcholine reception in the nervous system, inducing anticholinergic syndrome. The boy had babbled to his friends about the miniature reindeer flying around his head, prompting one of his friends to—thankfully—run to Professor Sprout, who had sent Severus an urgent patronus.
Now, the boy lay in a coma, his skin a pallid color, his condition slowly declining.
Severus inhaled, closing his eyes for a moment. Acetylcholine wasn't being processed, causing the symptoms they were seeing; this would escalate if not addressed. The chemical was instead falling to the wayside, broken down by cholinesterase before it could be reabsorbed. If he could…no, that was too risky. Severus shook his head, but his eyes went again to two jars on the top shelf, carefully labeled 'Physostigma Venenosum' and 'Hippomane Mancinella'. Both were sealed and labeled in Latin to deter nosy students and avoid exactly this sort of situation.
Sighing, Severus directed another long look at the unconscious boy, shielded on the cot in his lab. Poppy, with full confidence in Severus, had gone to check on her other patients. He knew it was possible; even muggles had begun exploring the chemical interactions affecting the brain, in their search for a treatment for Alzheimer's.
He reached up, carefully pulling the first jar down. He peered at the innocuous looking beans inside. Calabar beans, high in physostigmine, were easily as deadly as the belladonna; it took merely half a bean to kill. The other jar also held a toxic ingredient: fruit of the manchineel tree, another physostigmine source.
"Perhaps…"
He quickly composed a plan of attack; optimal quantities and preparation of ingredients, cauldron choice, and stirring techniques all flying through his head. Robes swirling around his ankles, he rolled up his sleeves and summoned the items, spelling them to hover next to him as he prepared the workspace.
A leaded crystal cauldron for purification, with the added benefit inhibiting the magical properties of the antidote, enabling a time controlled release. Complementary oils for a base, finely blended. A quarter of a Calabar bean, ground and mixed with the oil before introduction to the cauldron.
"Three stirs anticlockwise," he murmured absently, the rhythm of brewing soothing him.
He carefully plucked one manchineel fruit, minced it, and sprinkled it evenly over the surface. He swore as some of the sap dropped on his thumb as he returned the cutting to the jar; a blister formed instantaneously. He despised working with manchineel; the sap was a nightmare. Casting cooling and stasis charms on his hand, he returned to the cauldron and brought it to a simmer over low heat.
This mixture should inhibit the cholinesterase, allowing the acetylcholine to build up instead of being dissolved, thus kicking the nervous system into gear. The danger was in administering too much, or allowing the physostigmine to continue to build up once balance was restored. Both could be deadly.
Severus snatched another bezoar, shrinking and setting wards on it, before lowering it into the cauldron. The wards would sense when balance was attained and disable, allowing the bezoar to absorb the superfluous antidote before it could become toxic.
Pursing his lips slightly, he summoned three pixie wings—inherent hyperactivity should stimulate the parasympathetic nervous system further—from the net in the corner and ground them to a fine powder. Glancing into the cauldron, he noted the mixture had emulsified and turned a deep purple color. He gave it one clockwise stir as he added the powder, then five figure eights to incorporate it. Severus nodded in satisfaction when the potion lightened to a pearlescent lavender hue.
"A dare, indeed," he griped, tension gone. With the pressure of necessity lifted, his irritation was free to rise to the surface. "The dunderheads would dive off a cliff if dared." As he cleaned up, he became engrossed in his muttering about dunderheaded foolishness.
"Now Severus"—Severus started and turned to see Poppy returning. "It's not their fault; Hufflepuffs are social by nature."
"Yes, but it's getting worse," he answered. "Why wasn't Greenhouse 5 locked? That section only has dangerous ingredients. A second year should never be there."
"She trusts them, you know that. And it's never been an issue before…" she trailed off at his quelling look, both turning to look at the boy once more.
"Nevertheless, it's an issue for the staff meeting." He poured a vial of antidote. "This should be sufficient." He knelt by the boy and sat him up carefully, nodding to Poppy to initiate the diagnostic charms. He administered the potion bit by bit, massaging the boy's throat to induce swallowing. Poppy watched the indicators displaying the levels of acetylcholine and physostigmine in the boy's system.
As it leveled, she opened her mouth to speak; he held up his hand, watching for the flare that would signify the release of the wards and the spelled bezoar.
"There!"
They held their breath, gazes alternating between boy and diagnostics. Finally, the numbers equalized, settling in a jewel green tone.
"He'll be fine. I could have done better if I'd had more time and access to certain other ingredients, but…this will suffice."
Poppy patted his shoulder. "Thank you, Severus. That was…I have no words. Why don't you go add some wards to those greenhouses? Perhaps we can avoid another incident. I'll stay with him."
"Indeed."