At Platform Nine and Three-Quarters of King's Cross Station, the Hogwarts Express was set to depart in fifteen minutes.
Jon Hart was already on board. After more than half a month of a dull Christmas holiday, he could finally return to school.
Yes, "dull" was the only word that could describe the break in Southampton—no magic allowed, hardly any books to read, and not a wizard in sight within a hundred miles. Each day passed with little more than practicing Occlumency, then nothing else.
Fortunately, he'd managed to persuade Eric and Judi to let him travel to London alone and catch the train back himself... Otherwise, the holiday would've been a complete waste.
He found a compartment to himself, placed his luggage on the rack, and carefully pulled a diary from his pocket.
Its black cover was worn and old, the pages inside yellowed with age... It was clear this diary had been around a while. From afar, it even gave off a slightly eerie vibe.
Jon, disguised as "Varian Urien," had wandered through several streets in central London all afternoon before finally finding it in a used bookstore—for fifteen pence.
Now bored while waiting on the train, he opened it and began writing on a blank page:
"Polyjuice Potion, recorded in Most Potente Potions, is a powerful magical draught.
By adding an item from the intended target—such as hair or fingernails, but primarily hair—and drinking it, one can take on their appearance for a period of time.
Ingredients required include: lacewing flies, crude antimony, de-mouthed leeches, fluxweed picked at the full moon, powdered ammonium chloride, knotgrass leaf powder, bicorn horn powder, saltpeter, mercury, iron filings, and dried boomslang skin.
Though complex, the brewing process is not particularly difficult.
Roughly 5ml grants about 10 minutes of transformation;
50ml offers around an hour;
A large dose (over 1L) can sustain the form for up to 24 hours.
However, 24 hours is the maximum—no amount can extend it further.
The potion initially tastes like overcooked cabbage, though its color and flavor shift depending on the drinker's feelings toward the target. (If you like the person, it's tolerable; if not, it can be vile.)
It is only suitable for human transformation—not animals. Attempting to become an animal causes severe side effects. Trying to transform into a human-animal hybrid (like a half-giant or werewolf) is largely ineffective and likely harmful.
Successful transformation replicates physical traits like voice, strength, and reflexes—but not magical abilities. You can't expect this to make you a powerful wizard.
There are confirmed cases of gender transformation using the potion, but..."
By the time he finished, the page was covered edge to edge with notes about the Polyjuice Potion. So he carefully tore it out.
Folding it neatly, he marked the outside with the letters "P-P" (for Polyjuice Potion), then tucked it away in a hidden compartment in his suitcase, placing it with a small stack of other notes.
...
The compartment door gave a soft knock.
Jon quickly slipped the diary back under his cloak before looking up.
"Come in!"
"Jon..." A pretty girl with golden curls and a slightly childish face pushed the door open.
They'd already agreed by letter to meet here.
"Merry Christmas!" She blinked at him.
"You too, Astoria," Jon nodded.
She sat across from him, and they chatted casually for a while.
"How was your Christmas present?"
"Great!" Astoria's face lit up. "Unbelievable, really... That three-sided makeup mirror was amazing—I loved it! Even my mother praised it, and you know how stern she usually is!"
"Is that so? That's great," Jon smiled.
"What about mine... Did you find the secret I hid in the Chocolate Frog?" Astoria asked suddenly, blushing slightly.
"Uh... secret?" Jon froze.
He didn't like chocolate, so he'd only eaten a few of the frogs she gave him before setting the box aside.
He had no idea there'd been a secret hidden inside!
"You idiot... Hmph!" Astoria huffed and turned her face away.
She decided to ignore him.
...
Fortunately, their silent standoff didn't last more than a few minutes.
The smiling trolley witch arrived just in time to break the tension.
As they munched on cauldron cakes and pumpkin pasties, Astoria seemed to forget her earlier frustration.
After finishing a licorice wand, she suddenly remembered something.
"I heard..." Astoria whispered, "there was another attack at Hogwarts."
"Really?" Jon frowned slightly.
"Sir Nicholas—the Gryffindor ghost—was attacked, along with a Hufflepuff student, Justin Finch-Fletchley," she said seriously. "They were both petrified, just like Mrs. Norris and Colin Creevey. It happened a few days after we left school."
"I see..." Jon nodded with a blank expression.
Just as he'd expected. According to the original story, Nick and Justin should have been attacked around this time. He hadn't heard anything during the holidays, likely because Hogwarts had suppressed the news—but that wouldn't work on influential families like the Greengrasses.
"I wanted to write and tell you about it..." Astoria continued, "but my mother stopped me. She said news like that shouldn't be shared around."
"Yeah." Jon nodded slowly. "Professor Sprout's Mandrakes should be mature in a few months. Once they're ready, the petrified students can be revived. Everything should go back to normal."
"Be careful!" Astoria suddenly lowered her voice and leaned closer.
She spoke in a hushed tone, but Jon could feel the worry behind it.
"My mother almost didn't let Daphne and me return to school... Hogwarts is really dangerous. The monster from Slytherin—it's real!"
"I know... and thank you."