"...Held it in all night, didn't you?"
William didn't pause for long, the magic wand in his hand still emitting a faint golden light, slowly stripping away the curse wrapped around the old man's arm.
"I actually wanted to stop you at the time— it was a bit overconfident of me."
Dumbledore chuckled, a trace of "a hero in decline" melancholy on his face, but William's next words interrupted the old man's sentimentality.
"Forget it, even if you were thirty, you couldn't have stopped me."
"..."
Dumbledore was once again met with silence. He pondered for a moment, then decisively decided not to continue discussing this issue and instead said in a slightly serious tone, "William, the Sorting Hat's choice shouldn't actually be interfered with, for over a hundred years, it's discerned the essence of every student and guided them to where they can grow best..."
"You're saying nothing ever went wrong, or are you suggesting — "
William flicked his hand, dispelling the black energy wrapped around the wand's tip, "Do you think Voldemort turned out well? You want Tom to walk the same path again now?"
"...It won't be the same."
"Are you counting on that bunch mostly bred from close-kin marriages, not to bully an orphan with no parents? Or do you think in such circumstances, Tom wouldn't leverage my, or your status to bully others?" William's tone was very calm.
"That's a bit of a personal attack... even among Slytherin, there are good kids."
"Of course."
William paused, "Just like Gryffindor also has bad students— there's no perfect choice, but at least if Tom lives in the Gryffindor dormitory, he wouldn't have arthritis and rheumatism at such a young age, with knee pain every time it rains —"
"...That's what you're really focused on, isn't it?"
"You read me well."
"...Forget it, William, I'm not joking with you. The Sorting Hat tests the nature of the child. If Tom feels out of place in Gryffindor, would he face rejection, or even stir up something in his heart... that boy is not ordinary."
Dumbledore sighed, "Sometimes I even wonder if he really has been reborn, as you said."
"Of course, it's just because the soul isn't complete, so Tom can more easily feel or see the essence of those around him. If you put him in a snake pit... with ambition praised and surrounded by peers, he'd just find his companions faster— rather than that, it's better to throw him into a lion's den, and hopefully, he becomes a standard Gryffindor, a hot-blooded fool."
"...Did you just insult me?"
"You could tell? That proves you're not a fool."
William tugged at the corner of his mouth, and the magic wand pressed against Dumbledore's wrist shone brightly. He decisively lifted his hand, controlling the golden light at the tip to "pinch" another wisp of black energy and yank it out harshly, which was thoroughly pulled out and crushed in the air as a palpable, bone-chilling black mist.
"Alright, maybe it will last a week?"
William exhaled a long breath, "At least, it can change your hand from a fossil back to human, for now, take care, eat less spicy food, read more, watch the news, eat less snacks, sleep more..." William rattled off a bunch of instructions, then frowned, "Forget it, I'll hand the list to Professor McGonagall later—"
"...She doesn't know about this yet."
"Not planning to tell her?"
"...You shouldn't tell her either."
Dumbledore kept a bitter face, indicating he would follow "doctor's orders," as long as William didn't blab to Minerva.
"Fine— treating it a few more times like this, there won't be any immediate issues, as for a complete cure."
William put away the magic wand and gulped down the completely cooled lemon tea beside him, "I still need to think of a way, the Philosopher's Stone completely distorted Voldemort's curse, now this thing has some traits of ancient magic—"
"It's already very good."
Dumbledore moved his fingers a bit, the relief after the pain disappeared made him let out a sigh, "Thank you, William."
"No need for thanks, just pay me."
...
After leaving the Headmaster's Office, William went to find his chief inventor under him— and as soon as Grindelwald saw William appear at the door, he instinctively tugged at the corners of his mouth, "Well, well, well, if it isn't our Dueling Class Professor? What wind blew you here?"
"You look like a resentful woman in a deep boudoir—"
"Get lost!"
Grindelwald laughed and cursed, then his expression grew slightly serious, "…Tell me, how many days does that old man have left?"
"I don't know, but perhaps he won't die?"
"Bullshit, I've seen the curse on him, just touching it would deepen the curse's progress —"
Grindelwald's face showed no change, making it hard to decipher his current emotions, "Do you really think you can cure that thing?"
Do you hope for his recovery? Or the opposite?
William couldn't quite figure out these two old frenemies who had loved and hated each other for a lifetime, so he simply decided not to ponder it and said directly, "Don't use your rudimentary magic knowledge to gauge my abilities, when I galloped across Scotland back in the day, you were still learning Lumos— what's with that look? Not convinced? Want to duel?"
"…Seems you really have a way."
And so, Grindelwald laughed, apparently having made those expressions just to coax the truth out of William— ensuring that this "doctor" wouldn't promise anything just to pacify patient's relatives.
"…Idiot."
Having figured it out, William returned the man's gesture with a middle finger, "Alright, let's talk business— the network issue, how's your research going?"
"Learning from Muggles won't work this time."
Grindelwald shook his head, "Launching modified magic satellites into space would only cause them to completely lose connection—"
"Is that so... wait, you've already tested it?"
William was just about to nod and say he understood when he suddenly caught a blind spot, his eyes widened in confusion.
"—During your 'quality family time', the rockets had already launched twice."
…
Late at night, William finally emerged from the Muggle Studies Class, and conveniently picked up Mrs. Loris, the guiding cat respawning at the classroom door, holding her in his arms as he smoothly walked downstairs. Instead of climbing to the seventh floor to find the tapestry, it was better to head straight for the Hufflepuff Common Room to take a shortcut—
But, as William hummed a tune while passing the fish-shaped statue beside the Great Hall, a hand suddenly reached out from behind the statue, grabbing the hem of his robe.
"Wait, Professor."