Treasa darted forward, reaching Lupin almost as soon as he hit the floor. Severus stiffened against the wall, giving the wand at his side the merest flick. Homenum Revelio. He felt the magic spread out around him, searching through the house for other humans.
His wand vibrated four times. Four occupants, all of them in this hallway. No possibility of a surprise attack.
"Let the werewolf lay," screamed the portrait of Mrs. Black, accompanying her triumphant tones with a peal of demented laughter. "One less blight on this noble house."
"SHUT UP!" Sirius roared, rounding on his mother's portrait with a Stunner that scorched the air by Severus' face.
The spell seemed to work for the moment. Mrs. Black looked far too shocked to immediately continue her tirade. Sirius took up the curtain Lupin had been wrestling with, jerking it almost closed in one, manic heave. He shuddered with the effort. A near-inhuman growl curled from his throat.
Severus took hold of the other side, stretching it the last few inches to meet its straining partner. Black's eyes unscrewed and darted to his face, disbelieving. Severus merely released the curtain and turned away, still scanning the hallway for anything that could have caused Lupin's collapse. There were any number of murderous objects in this house.
Treasa was casting basic diagnostic charms, her wand shifting from heart to skull to abdomen with the smooth flow of habitual work. Black had thrown himself down on Lupin's other side, eyes glued to the sweeping motions of the verawood wand.
"Well, Treasa?" Sirius asked as the silence stretched into eeriness.
"No head injuries, nothing internal," Treasa replied, almost absent-mindedly. "Ah, there!" Her wand paused near the base of Lupin's right ribs, visibly pulsing.
She laid the wand aside and probed the area with her fingers. Severus, rather fascinated despite himself, stepped closer to observe her work. He had once scoffed at the idea of being a Healer himself, but Slughorn had been right that the intricacies of the work were intriguing in their own right. Treasa's movements were steady and sure, but infinitely careful. She peeled aside Lupin's black outer robe, grimacing at the spreading dark stain on the faded gray shirt he wore underneath. It clung slightly to the wound underneath as she attempted to pull it away.
It was a rounded slash in his side. Severus realized with a detached thrill of recognition that the edges bore the unmistakable impressions of teeth, though from a jaw too elongated and canines far too large to be human. Treasa was frowning, probing at the seeping edges with her left hand.
There was a sudden shift in Lupin's breathing as Treasa pressed on the wound – a sharper inhale, a groan on the exhale. Treasa drew back, eyes on Lupin's face, left fingers instinctively cupped to avoid dripping the blood that clung to them. When he gave no other signs of reviving, she picked up her wand, casting a rapid-fire set of charms that left the wizard utterly limp, his breathing now steady and relaxed, the blood from the wound cleared away, and the edges beginning to close.
"He's..." Black apparently had no intention of continuing the sentence. He seemed incapable of drawing his eyes from the ugly gash.
"He'll be fine," Treasa said briskly. "Bite wounds such as that are a Knut a dozen around St. Mungo's. I've healed more than -"
But she broke off, frowning. Severus could see why even from his vantage point several feet away. The edges that had begun to draw together were retracting once more, blood seeping in a manner that gave him a strong feeling of deja vu.
"What in Merlin's bloody pants?"
Severus had the distinct impression Treasa had not intended to verbalize the muttered query. She was leaning over Lupin again, waving her wand in the same pattern she had used before. Again, the wound began to heal over, only to pull back in an eerily familiar pattern.
"Treasa," Sirius began, voice quivering rather less noticeably than his body. "It's not working."
This time, Treasa's exclamation was stronger. She changed tactics, giving a simple double spiral that had no effect whatsoever. Two more silent spells, then she snapped in exasperation, "Abracabrius vigorato!"
Black looked as if he might go to pieces where he sat. Severus could only hope that such an action would prove equally difficult for Treasa to heal. He'd heard of that last spell. It was rarely used, a sort of last recourse when targeted charms had no effect. The werewolf was rather stubbornly still bleeding. Werewolf...
"Where are your potions ingredients?"
Both Treasa and Black started, heads whipping around to where he stood. Treasa's eyebrows were furrowed.
"Listen, Snape, this is no time -"
Treasa cut across Black's threat, "You have an idea, Severus?"
He controlled the startled jump of his muscles by pure instinct, keeping his eyes on Treasa though he longed to see if Black had noticed her use of his first name. "Lycanthropy."
Her eyes widened in comprehension. "Basement."
He kindled the fire under the first cauldron on the table as soon as he stepped in the door. "Accio moonstone, aconite and salamander blood."
A large vial and two cloth bags soared off the shelves and landed neatly next to the cauldron. He poured half the salamander blood into the cauldron and ripped two sprigs of aconite into quarters, not bothering with the knife to chop it finer. For this particular plan, finesse was less important than speed.
With the two ingredients sluggishly coming to a boil, he searched the shelves for fluxweed. There was no time to test his theory that the wound was reacting badly to Lupin's monthly transformation, and the paste he was creating was pure invention of the moment. If Treasa had thought to purchase new-moon fluxweed as well as full-moon, he might be able to use a pinch in the paste to counter the changing properties of the wound. He had not risked Summoning the leaves for fear his spell would not make the distinction he needed. It had happened before.
There were four tins marked "Fluxweed," each with a different drawing of the moon on the label. He grabbed the one with a blacked-out circle, thanking Treasa mentally for remaining as meticulous as he recalled.
"If this works, you may finally have won that Order of Merlin for yourself, Severus," he muttered in half-sarcasm, grabbing a pestle to prepare the fluxweed.
He let the mixture simmer for exactly 60 seconds without stirring before adding the moonstone powder. It was already starting to congeal,taking on the consistency of pudding. If his theory was correct, the moonstone would work with the fluxweed to counteract the lycanthropic symptoms and activate the salamander blood's restorative properties when the healing began, speeding the process.
The final result was a gloppy, irridescent blue. He eyed it skeptically as he poured it into a bowl. Far from his best work, and if he'd gotten it wrong in any way, he would have the full fury of the Order to deal with. He doubted even Dumbledore's protection would be enough to spare him if Black thought Lupin had come to more harm because of him.
Treasa was in much the same position he'd left her, muttering spells in a rapid-fire manner, though none of them seemed to have much effect. He passed the bowl to her and stepped back, wand raised in preparation for whatever reaction was forthcoming.
She, in stark contrast to the panicked Black at her side, had returned to her calm, brisk Healer demeanor. She scooped the paste out with her left hand and smeared it on the wound.
"Can't believe I didn't see it sooner," she said, addressing her comment to Severus, though her eyes remained fixed on her work. "Same principle as Animagus attempts and faulty transfigurations."
Black looked predictably as if he hadn't quite managed to follow her reasoning. Severus indulged in a moment of pleasure at his confusion. "The paste should halt the transfomations long enough for your spells to take effect."
She pointed the wand at the wound and did two figure eights while murmuring, "Vulnaverto vigorato."
The bite marks eased together, pulled slightly back, then completed the healing by absorbing the last of the paste and sealing themselves seamlessly. Lupin stirred, attempting to push himself up off the floor.
"Rest for a moment," Treasa admonished, hand on his shoulder. "You'll need your strength for the tongue-lashing you're in for. Been keeping that bite a secret have you?"
Lupin's hand went to his side. "How did you manage that? I've been trying for -"
"Nigh onto two weeks, by my calculations," Treasa supplied.
He had the sense to look abashed. "It – it seemed to be healing," he offered, trying again to edge into a sitting position. "Merlin's beard, I'd forgotten what it was like to move without pain. You're a miracle worker, Treasa Shannon."
Severus Summoned the bowl from the oh-so-touching scene, prodding the blue residue with his left index finger. It was a rather ingenious concoction, a shame there would never be a market for it. Werewolves weren't frequent patrons to Diagon Alley, preferring the ministrations of their own kind. Still, perhaps the Institute of Magical Research might take an interest in it as something of a derivative of Wolfsbane.
Black was helping Lupin to his feet, relief making his already-loud voice positively raucous. "Moony, you bloody fool, the next time you pull a trick like that, I give Treasa permission not to heal you."
"It wasn't just my spell," Treasa protested, waving away Lupin's thanks. "Really, it was Severus who came up with the idea that your lycanthropy was the key." She turned toward him, something rather like respect in her eyes. "And it was his potion that gave the spell a chance to work."
"Well, then, Severus," Lupin broke away from Black and crossed the hall with hand outstretched. "Your talent with potions saves me yet again. My thanks."
Severus tightened his grip on the bowl, feeling rather than seeing Black's stifled protest. He wanted Lupin's thanks less than Black wanted him to give it. The honest smile on Lupin's face faltered as his proffered hand was not met. Behind him, Treasa's brow creased.
"May I suggest that the next time you have a disagreement with one of your kind, you take care not to let it happen during your transformation?" Severus said finally, keeping his voice and face expressionless. He made rather a production of conjuring a large phial for the paste and using his wand to transfer it from the bowl. "I presume that was what caused the fluctuations of the wound, correct?"
Lupin let his hand drop, covering the frustration in his tone fairly well. "Yes, well, I hadn't planned on Greyback's clan finding the group I was staying with last month. I'll do my best to keep it from happening again."
Severus sealed the phial with a half dram or so left in the bowl. He held it out to Lupin stiffly. "In case you don't manage it."
The werewolf accepted it with more graciousness than it was offered, Severus had to admit. Lupin took the bowl down the hall and disappeared into one of the doorways. A moment, a breath too long, Severus stood motionless in the corridor. Long enough to notice that Black already had Treasa laughing at some inane comment and was taking advantage of her laughter to edge another half-step nearer. Now their bodies were close enough to one another that Severus doubted a demiguise could have fit between them. He turned toward the door, fully intending to slam it on the way out so the portrait of Black's mother would re-awaken.
"Severus."
It was the second time Treasa had called him by name in the presence of Order members. Severus attributed the odd half-lurch in his midsection to suppressed frustration that she would be so careless. She, after all, was the one who was so intent on pretending they'd never met outside of school. He turned on his heel and almost took a step back. Rather than remaining with Black, she'd covered the length of the hall that separated them, standing only a few inches behind him.
Severus chose to simply look at her. If she wanted to speak, she could.
"Stroke of genius, that was," she said, her brogue coloring her words.
She paused, evidently waiting for him to respond, which he had no intention of doing. For him to do anything other than stare coolly at her would be uncharacteristic enough for even Black to notice.
Treasa's expression slid toward exasperation, then halted. "Just wanted to thank you for helpin' me with the cure. I'd hate to lose a patient so soon after moving into headquarters."
She was frustratingly close to divulging that she which insisted be kept secret. Severus couldn't fathom what she meant by it. It was not her neatest attempt to bait him, and he couldn't be sure that was what she was trying to do. Black's blazing, hate-filled eyes found his over Treasa's head, clearly daring him to do anything he found offensive or rude.
His best recourse was his original plan. The door-muffled screech of Mrs. Black was rather hollowly satisfying as he strode away.