Let's rewind time a little. Over on Arthur's side, he was sitting with Hermione, accompanying her as she read.
But his attention was fixed entirely on Diagon Alley, so in Hermione's eyes, he looked completely absentminded.
No matter what she asked him, Arthur's replies were always: "Mm.""Ah.""Sure."
Watching her cousin in such a daze, the little witch couldn't help but get the urge to tease him.
"Cousin, did you invent a new spell recently?"
"Mm."
"Can you teach me?"
"Ah."
"Alright then, I want to learn that spell that turns a wand into a sword!"
"Sure—wait, what? How do you know I can use the Carian Greatsword?!"
At that moment, the business in Diagon Alley concluded, and Arthur snapped back to himself—only to realize Hermione had tricked him.
"Hmph! So it's called Carian Greatsword. That day in the garden, I just happened to pass by and saw you casting it."
"And you looked so silly swinging that sword around!" Hermione huffed proudly.
"I was practicing swordsmanship!"
Arthur scratched his cheek awkwardly, trying to argue back.
He had just learned Carian Greatsword not long before. On a whim, he'd wanted to try out a sword technique, but since he'd never studied actual swordsmanship, he ended up flailing clumsily. Who could have guessed Hermione would catch him in the act?
"Don't change the subject. You already promised me—no backing out!"
"Fine, fine, I'll teach you! But we have to agree—unless it's an emergency, you can't use my magic in front of others."
"Got it! Now pinky swear."
After they hooked pinkies, Hermione's stomach growled loudly.
Her cheeks flushed red, and she didn't dare say anything—just looked at Arthur with pleading eyes.
Arthur didn't expose her embarrassment. He stood up and headed to the kitchen.
"Well then, it's lunchtime. Time to cook."
The Grangers didn't come home for lunch on workdays—being dentists, their schedules were busy—so usually, it was just Arthur and Hermione at home.
Thanks to his pre-transmigration otaku lifestyle, Arthur was fairly skilled at cooking. He hadn't liked going out much, so after binge-watching food bloggers online and refusing to mistreat his stomach, he'd picked up the habit of cooking for himself. Over time, his culinary skills had become quite good.
Just a few days earlier, fed up with British cuisine, he'd whipped up a couple of dishes on a whim—completely winning over the Granger family's stomachs.
That night, once Arthur logged in, he went straight for the ruins of the Roundtable Hold.
"Oh! My adorable disciple! How have you been? You haven't come to visit your teacher in quite some time."
"Hehe, I've been alright, I guess."
Arthur chuckled awkwardly.
Well, it'd be better if I hadn't gotten lost in Stormveil Castle, he grumbled inwardly.
Changing the subject, he pulled out a Philosopher's Stone.
"Teacher, I recently got my hands on this strange stone. Could you take a look?"
"Oh? Let me see."
Sellen accepted the stone and channeled magic into it.
The moment her mana touched it, the stone began glowing a brilliant red.
"A remarkable stone. A high-grade alchemical product. It can replenish life force… and it even seems capable of transmuting materials into gold."
"But its energy reserves are almost depleted. Disciple, what do you want with this thing? It's not even as useful as your Crimson Tears Flask."
Arthur couldn't help admiring Sellen's magical mastery. Just from a simple mana probe, she had already unraveled most of the stone's nature.
"Teacher Sellen, please look closely at its shell. When I acquired it, I also received some information—apparently, this stone can be used to brew elixirs that extend one's lifespan. Could I trouble you to analyze its crafting method? I need this knowledge."
Hearing that, Sellen shifted her focus to the stone's casing.
"Oh? If you hadn't mentioned it, I wouldn't have noticed. The energy within is ordinary, but the vessel itself is extraordinary."
"This kind of alchemy doesn't belong to Raya Lucaria, nor to the royal family of Caria… Could it be from the Royal Capital, Leyndell?"
"Transmuting matter into gold—it certainly fits their style."
"But, disciple, a word of caution. As you continue drawing power from Runes, your lifespan will lengthen naturally. Don't get distracted chasing some so-called eternal life."
Arthur saw Sellen mistake the Philosopher's Stone as a relic of the Golden City but didn't explain. He simply nodded repeatedly.
"Yes, yes, of course. Don't worry, Teacher. My pursuit is the essence of magic itself. I'd never be foolish enough to chase after immortality."
(Qin Shi Huang: "I feel offended!")
He didn't tell Sellen the truth—that what he wanted from the stone was its ability to create bodies capable of housing souls.
Originally, he'd thought about asking her to study the techniques of human transmutation, but on second thought, that was more up Voldemort-senior's alley. Clearly, Tom Riddle had developed a complete system of research, otherwise he wouldn't have risked infiltrating Hogwarts just to steal the Philosopher's Stone.
Too bad for Tom—Arthur had beaten him to it.
"Hmph, it's good you have that resolve. Still, it is better to keep your feet on the ground. Analyzing the crafting method of this stone will take time. In the meantime, you'll study alchemy with me. Otherwise, when the knowledge is in front of you, you won't even understand it."
"Understood, Teacher Sellen."
"Oh, and about the creation of the Albinaurics—you'd like me to teach you that as well?"
Arthur was planning to combine the Lands Between's Albinauric creation techniques with Voldemort's soul-revival methods… to craft a body for his future wife.
"Oh? You already know of the Albinaurics? That means your journey has taken you to Liurnia, hasn't it?"
"Ah, such nostalgic lands…"
"Very well. I'll teach you that too. But brace yourself—alchemy is nowhere near as simple as the magic you've learned so far."
In reality, Arthur hadn't even left Stormveil Castle yet. Even after defeating Godrick, he was still wandering inside… still lost.
From then on, Arthur immersed himself in the study of alchemy.
This discipline—barely even mentioned in the game—took him a whole month just to grasp the basics.
Not because he couldn't understand the material, but because the foundational knowledge was vast. Memorizing alone took up most of his time.
On top of that, the Roundtable Hold had few resources, so he had to go out scavenging for materials while learning under Sellen.
Even in the daytime, at home, Arthur would be hunched over notebooks, scribbling symbols that looked like nothing more than chicken scratch (in truth, they were alchemical runes from the Lands Between).
Hermione, watching him draw those bizarre glyphs, began to suspect her cousin was either possessed or cursed by some Dark Wizard.
Thankfully, Arthur otherwise behaved normally. Otherwise, the little witch would probably have raised her wand and hit him with a good old "Stupefy!" to calm him down.
Yes, you read that right—our little witch had already mastered Stupefy, a spell meant for older students.
She had Arthur's Mimic Tear and the Mimic's Veil to thank for that.
After experiencing the convenience of the Mimic Tear, he'd disguised it with the Mimic's Veil, then snuck it into both Diagon Alley and Knockturn Alley.
His goal in Knockturn Alley had been to sell dragon's blood—since explaining its origin would have been… problematic.
With the money, he'd rushed to Flourish & Blotts, buying one of every book he could find.
And right in front of the clerk, he stored them all into his system inventory.
The clerk, stunned at first, then turned around and reported him for illegal use of the Extension Charm.
That forced Arthur to cut his shopping trip short.
Later, he learned that the Ministry of Magic strictly prohibited the private use of Extension Charms. Only authorized companies approved by the relevant magical department could manufacture such items.
That's why legal products like school trunks and family tents bore the Ministry's official seal.
Since the clerk hadn't seen any such seal on Arthur, he wasted no time turning him in—probably hoping the Ministry would confiscate the books and return them to the shop, letting him profit twice.
Arthur made a note to settle that score.
True to his "revenge before bedtime" philosophy, he immediately transformed into a book and snuck back into the shop.
The clerk noticed the old tome Arthur had become but thought nothing of it, assuming some customer had dropped it. He casually tossed it into the secondhand section.
That night, when the shop was empty, Arthur reverted to his real form, swept the entire secondhand section into his inventory, and even retrieved the money he'd spent earlier. A perfect "zero-cost acquisition."
Don't underestimate those secondhand books—though most were worthless junk, sometimes there were treasures hidden among them: textbooks filled with diligent student's notes, or notebooks discarded by careless wizards.
One can only imagine the clerk's face the next morning when he found the secondhand section stripped bare and the till emptied.
Oh, and speaking of schoolbooks… I wonder if the Weasleys had already bought Ron's first-year supplies.
If not, Ron would be thrilled. With the secondhand section cleared out, Mr. and Mrs. Weasley would have no choice but to buy him brand-new books.
Then again… they might just hand him one of his older brothers' spares.