The underground laboratory smelled faintly of lavender, mint, and something sharper, a note of crushed peppermint leaves steeping in the cauldron at the far end of the workbench. Cela sat bent over her parchment, quill scratching quickly across the page. A half-empty inkpot rested at her elbow, its rim dark with smudges. Her hair was pinned back untidily, strands escaping as though they, too, were impatient to be free of her focus.
It was the last week of July, hot and sticky above ground, but the cellar beneath the Slughorn family home kept cool, and Cela had chosen it as her refuge. Hermione had visited her a few times earlier in the month—bright-eyed, always curious, poking around at Cela's notebooks and pestering her with questions about measurements and ingredients—but Hermione and her parents had gone to France on holiday the week before. Cela missed her friend's chatter, but the quiet was welcome now. This was the week she had to finish everything.
Her hand cramped as she scrawled down the last of her "Methodology" section. She had already written two research papers before, little projects under her grandfather's supervision—analyses of potion stabilizers, a comparative essay on bezoar effectiveness against modern toxins—but this, this was different. This was hers.
Her first true invention.
Cela leaned back in her chair, stretching her sore fingers. The cauldron behind her hissed softly, the brew simmering to a gentle turquoise, proof that she had gotten the final variation correct. A potion for children, she had told herself, for anyone really—but easy, safe, harmless, and clever. A potion to solve a problem no one ever seemed to talk about but which she had noticed far too many times.
The problem of bad breath.
She could still recall the first spark of the idea, years ago: sitting across from an old wizard at a gathering her grandfather had hosted. He had been kind, friendly, full of stories—but the smell of wine and sour butterbeer on his breath had been so strong Cela could barely keep from wrinkling her nose. Even her grandfather's closest friends suffered the same. Wizards, it seemed, cared for their robes, their beards, their wands—everything but their mouths.
Yes, there was the old Mouth-Washing Potion, a relic from centuries past, still sold in a few dusty apothecaries. But Cela had tried it herself. It worked only for an hour or two, leaving behind a bitter metallic taste, hardly an improvement. In truth, it was miserable.
Cela had wanted something better—something lasting, pleasant, and affordable for ordinary wizards and witches to buy.
She had taken notes from the Muggle world too, sneaking looks at their toothpaste and flavored chewing gums. There was genius there, in the way Muggles made daily hygiene simple and even enjoyable. Why couldn't wizards do the same?
So she had spent five years tinkering, testing, discarding variation after variation. Too strong, too weak, too sticky, too bubbly. More than once the potion had exploded into froth and stained the ceiling blue. Another time, it turned her tongue purple for a week. She had refused to let her grandfather fix it. "It's mine," she had told him stubbornly at eleven, "and if it goes wrong, I'll ask." And Horace Slughorn, half-amused, half-proud, had indulged her.
Now, at thirteen, she had it perfected.
A potion that removed unpleasant odors from the mouth entirely, keeping it fresh for a whole day, sometimes two. More than that—it could be flavored. Strawberry, mint, lemon, vanilla, even chocolate if one dared. Harmless, safe, and even fun.
She dipped her quill again and began on the conclusion.
⸻
Research Findings and Conclusion
The Flavored Mouth-Freshening Potion, developed independently between 1988–1993, demonstrates an effective and lasting improvement upon the archaic Mouth-Washing Potion. Trials indicate odor elimination for 24–36 hours, with complete safety in children and adults alike. Flavor charms integrated within the brewing process allow for personalization of taste, a development unprecedented in hygienic potioneering.
Future uses may include commercial adaptation for daily use, educational adoption in schools (providing children with both hygiene and choice), and integration into healer wards where long-term oral freshness may benefit patients. The potion is stable, affordable, and requires no rare ingredients, making it accessible for mass production.
Cela set the quill down at last, flexing her fingers. Her research paper was finished.
Her heart beat fast. She had written other papers before, but those had been safe, academic exercises. This one was her invention. Hers alone.
She gathered up the parchment carefully, stacked them in neat order, then slid them into a green folder. She hesitated a moment, then took the vial of turquoise potion still simmering in the cauldron and poured it into a crystal phial. She stoppered it tight. The journal reviewers would want proof.
Taking a deep breath, she stood, brushed the ink smudges from her robes, and headed upstairs.
***************
Her grandfather's study smelled of sandalwood, parchment, and faint traces of mead. Horace Slughorn sat in his armchair, dressed as always in rich velvet robes that shimmered faintly in the lamplight. Even when no visitors were expected, he insisted on dressing finely. "One never knows when a guest may arrive," he always said, "and appearances are everything, my dear."
He looked up as Cela entered, clutching her folder. His Face twitched.
"Well, well! My industrious little brewer emerges at last! You've been hiding down there for days, Cela. What have you got for me, eh? Another essay on bezoars? Or have you at last brewed the Elixir of Everlasting Clean Cauldrons?"
Cela rolled her eyes but smiled, stepping forward. "No, Grandpa. This is it. The paper. The one I've been working on all these years."
Slughorn straightened a little in his chair, intrigued. "Ah. That one."
"Yes." She set the folder on his desk, then carefully placed the turquoise vial beside it. "I finished it."
His eyes gleamed. "Well then, sit, sit. Let's hear it from the inventor herself. Explain it to me, every detail. Pretend I'm one of those stuffy old reviewers from the Journal. Convince me."
Cela flushed but obeyed, sitting across from him. She opened the folder and began, her voice nervous at first but steadying as she went on.
"It's called the Flavored Mouth-Freshening Potion. It's an improvement on the ancient Mouth-Washing Potion, but instead of lasting only an hour or two, this lasts twenty-four to thirty-six hours. It completely removes unpleasant odors, and it's safe for children. No side effects, no bitterness. And—" she hesitated, then smiled—"you can flavor it however you like. Mint, strawberry, lemon. Even chocolate."
Slughorn let out a rich, delighted chuckle. "Chocolate breath! Merlin's beard, half the girls at Beauxbâtons would swoon at the idea. Go on, go on."
She explained her methodology, how she had altered the infusion stages, how she had drawn inspiration from Muggle toothpaste and adjusted wizarding flavor charms to bind with peppermint oil. She admitted her failures—the purple tongue, the blue ceiling—but showed him her notes where each attempt had led closer to success.
Her grandfather listened, stroking his mustache, nodding along, occasionally interjecting with a question. "Mm, clever. And it doesn't interact badly with pepper-up potions? Good. And stable shelf life, you say? Excellent. Accessible ingredients, too—ah, yes, I can see the commercial potential already."
By the time she finished, Cela was flushed with excitement.
Slughorn reached for the vial, uncorked it, and sniffed. The faint scent of fresh mint rose in the air. He swirled it, watching the turquoise shimmer, then dabbed a drop to his tongue. His eyes widened.
"Oh-ho-ho! Perfectly refreshing! And minty, too! My dear girl, this is brilliant!"
Cela grinned.
"Not only clever, but practical, marketable, and dare I say—profitable." His eyes twinkled. "Do you realize, Cela, that every wizarding household in Britain would buy this? Hogwarts alone could order it by the cauldron-load for their students. St. Mungo's too. Why, even the Ministry clerks could use it."
She laughed, shaking her head. "I didn't make it for money, Grandpa."
"No, no, of course not," he said warmly. "But innovation, my dear, must be recognized. And this—this deserves recognition."
He reached for his quill, drew a fresh sheet of parchment, and began writing. His script was bold, sweeping with confidence.
⸻
Endorsement for Submission to the Potion Journal
{As a certified Potion Master and long-standing member of the International Guild of Brewers, I, Horace Eugene Flaccus Slughorn, hereby submit the attached research paper and invention for review.
The work of Miss Celestia Slughorn represents an innovative and original contribution to hygienic potion-making. The Flavored Mouth-Freshening Potion is safe, effective, and elegantly brewed, offering significant improvement upon archaic methods. Its commercial and social value is undeniable. I have personally tested the sample provided and found it flawless in execution.
I urge the Journal to accept this research for publication and to recognize Miss Celestia Slughorn's achievement as a young innovator of remarkable promise.}
Slughorn set down his quill, signed with a dramatic flourish, and stamped it with his seal.
"There we are." He looked at her with eyes shining with pride. "Your first true invention, Cela. Off to the Journal it goes. I daresay you'll have letters flooding in before the summer's end. Potion Masters clamoring, shopkeepers begging for rights to sell it. Why, even the Ministry might come knocking."
Cela sat very still, her cheeks warm. For years she had dreamed of this moment, but now that it was here, it felt strange, fragile, like she might wake and find it had been only a daydream.
"Thank you, Grandpa," she whispered.
"Nonsense, nonsense. You did this yourself." He leaned back, smiling. "And I couldn't be prouder."
*************
Cela went to bed that night with ink still smudged on her hands and the faint taste of mint lingering in the air. For the first time, she allowed herself to imagine a future where her name, not just Slughorn's, would be known in the world of potions.
Her invention was real. Her paper was complete. And tomorrow, the owl would carry it to the Potion Journal.
She closed her eyes, heart thrumming with anticipation.