Having made his decision, Karl immediately sprang into action, heading to the Ravenclaw tower to find Nina and Helena.
After a brief discussion, Karl, now with his story straight, arrived at the gargoyle guarding the corridor on the eighth floor of the Castle.
"Hey there, Stubborn Mule, it's me, an old acquaintance. Mind opening the door?"
Gargoyle: (._.)
"Alright then, let me try a few passwords... Cockroach Clusters, Fizzing Whizzbees... Huh?"
To Karl's utter astonishment, the gargoyle sprang to life, hopping aside to reveal the spiral staircase behind it.
"Well, I'll be... Did I just get lucky, or has a straight-laced fellow like you started following procedure?"
He strongly suspected Dumbledore had given him a backdoor pass, letting him through with any old nonsense.
Ascending the spiral staircase, Karl soon reached the Headmaster's Office.
The portraits of past headmasters lining the walls immediately began whispering amongst themselves upon seeing him.
Phineas Nigellus Black, in particular, glared at Karl with open hostility.
"Look! Look! That sly, despicable little brat is back! What does he want this time?"
"Dumbledore, I must remind you, you are the Headmaster of Hogwarts. You should not be colluding with this brat!"
The man held a deep grudge against Karl, likely stemming from that line about 'returning all Sickles to the other three houses and splitting Slytherin's Galleons seventy-thirty,' which rankled this former Slytherin headmaster deeply.
"Headmaster Black, you're already hanging on the wall. No need for such fiery temper; you might spontaneously combust."
Hearing such disrespectful words from the seemingly well-behaved Karl, Phineas Black began hopping up and down in his frame in fury.
"Dumbledore! Expel him at once! A student like this has no place at Hogwarts!"
Dumbledore, who had been enjoying the spectacle, suppressed a smile and winked at Karl.
"You must maintain a headmaster's dignity, Phineas. Mr. Orolin is only a first-year student."
But Phineas Black was having none of it. "Headmaster's dignity? Dumbledore, you're always like this. I don't understand why you constantly favor and coddle these..."
"Silence, Black!"
Headmistress Delphini Delphini, hanging nearby, sharply cut him off. "Mind your language!"
"What's wrong with me? You're as peculiar as Dumbledore, always cozying up to those Muggle-born students!"
Before long, all the headmaster portraits had joined the argument between Delphini Delphini and Phineas Black.
It quickly devolved from random bickering into personal attacks, revealing a trove of hidden scandals.
Karl, munching on his metaphorical popcorn on the sidelines, felt immensely satisfied, like a Hufflepuff let loose in a melon patch with the owner away.
Wasn't this ten thousand times more interesting than any *Secret Little Stories of Hogwarts Headmasters*?
Unfortunately, Headmaster Dumbledore didn't let Karl indulge to his heart's content. With a gentle wave of his hand, a large curtain covered the entire wall.
It not only hid the portraits but also completely muffled the sounds.
After all, such mutual airing of dirty laundry among generations of headmasters wasn't quite suitable for a student's ears.
"Karl, what did you need to see me about?"
Hearing this, Karl immediately shelved his regret at missing out on the juicy gossip.
"Headmaster, sir, I wish to report Professor Heller for harboring sinister intentions, sowing chaos at Hogwarts, and committing crimes deserving of death!"
Dumbledore: (⊙ˍ⊙)
He gestured for Karl to sit down and poured him a steaming cup of Black tea.
"I believe we have plenty of time. Please, explain in detail."
"Right away!"
Karl sat down opposite Dumbledore and led with his trump card.
"Headmaster, Professor Heller used his Allure to lead me to the Room of Requirement, where I encountered Lord Voldemort."
The impact of this single sentence was considerable, instantly turning Dumbledore's previously gentle expression grave and serious.
"Karl, I truly didn't expect to hear that name from you. You certainly know who he is, so you wouldn't be joking with me, would you?"
"I'm serious, Headmaster. Inside the Room of Requirement, I found Ravenclaw's Diadem, and Lord Voldemort's soul was within it."
As for Dumbledore not knowing about the Room of Requirement, Karl had never believed that when he read the books.
Because the first mention of the Room of Requirement came from Dumbledore's own lips, and to an outsider at that.
While discussing school secrets with Igor Karkaroff, Headmaster of the Durmstrang Institute, Dumbledore mentioned once taking a wrong turn while looking for a bathroom and ending up in a beautifully furnished room filled with various splendid chamber pots. The room vanished after he left and he could never find it again.
Back then, Karl had only wondered why Dumbledore secretly winked at Harry, suspecting he was hinting at the existence of a magical room.
Later, when he learned the method to enter the Room of Requirement, Karl believed it even less.
Because he found it hard to imagine Dumbledore, in urgent need of a bathroom, pacing back and forth three times in front of a tapestry.
What, got lost in a single corridor?
Surely the old man wasn't on the verge of an accident, contemplating solving the problem right there?
Later, when *fantastic beasts and where to find them* was released, the mystery was finally solved. Dumbledore not only knew about the Room of Requirement but was also quite proficient in using it.
Dumbledore remained silent, meeting Karl's gaze, then let out a deep sigh.
"Ravenclaw's Diadem, Lord Voldemort's soul... combined, that is not good news at all."
"To choose to hide it in that room... his understanding of human nature is even more precise than I imagined."
"Karl, you communicated with him, didn't you? What did he say to you?"
In truth, since Grindelwald's imprisonment in Nurmengard, he had never visited the Room of Requirement again.
Karl feigned embarrassment, scratching his head, seizing the opportunity to bring the Fiendfyre Curse into the open.
"Lord Voldemort said he had conquered death and walked the path to immortality farther than anyone. He wanted me to follow him and teach me to create something called a Horcrux."
Hearing the word 'Horcrux,' a flash of light passed through Dumbledore's eyes. "And then?"
"Then I burned him with Fiendfyre. But he said he would meet me again."
Karl wore a look of contrition. "I'm sorry, Headmaster. I'd heard from Nina about the power of Fiendfyre, so I went to the Restricted Section on my own to learn the Fiendfyre Curse."
Dumbledore blinked, suddenly at a loss for words.
It wasn't just because a Horcrux of Lord Voldemort had been so easily destroyed, but also because of Karl's reason for learning Fiendfyre.
Nina must have learned about Fiendfyre from Queenie and Newt.
After all, one of them had crossed a ring of fire, and the other, along with Nicolas Flamel and others, had helped stop Fiendfyre from destroying Paris.
And the source of that Fiendfyre... was that man...
Gellert Grindelwald.