The high tower of Nurmengard was cloaked in a biting, frigid wind.
The door to the top-floor cell was ajar, as if it had always been waiting for someone to arrive.
When Dumbledore pushed the door open and entered, the cell's occupant was facing the one narrow window, which offered a view of the lead-grey sky and the endless, snow-capped mountains.
A hoarse voice spoke:
"The frequency of your visits over the last twelve years is frankly flattering."
Grindelwald turned around. He was wearing his usual grey robes and appeared thin and gaunt.
"I need your help, Gellert," Dumbledore said.
At Dumbledore's words, a curve played on Grindelwald's lips.
"So, you only remember this place when you have a request?"
The air instantly solidified.
Only the cold wind howled outside the window.
After a long silence, it was Grindelwald who broke it.
"Ask away. I'm rather curious myself. What could possibly be troubling Albus Dumbledore?"
He walked over to the simple wooden table and pulled out a chair, sitting down.
On the table lay a stack of unused parchment.
Dumbledore sat opposite him and immediately took an object from his robes, gently sliding it across the table toward Grindelwald.
Grindelwald stared at the old, worn black diary. A faint light flickered in his mismatched eyes. He stretched out a long, thin finger and stroked the cover of the journal.
"A Horcrux."
He breathed the word out softly. There was no question in his voice, only confirmation.
Dumbledore nodded.
Grindelwald's expression became entirely serious.
This object, even within the field of the Dark Arts, belonged to the most sacrilegious and wicked of forbidden practices.
The number of wizards who knew of its existence and its principle was already minuscule, but those truly willing and able to create one were the most insane of the mad.
Grindelwald furrowed his brow.
Years ago, he too had briefly considered the idea of creating a Horcrux to ensure his survival, but the thought had been as fleeting as a shooting star.
To achieve his vision for 'the greater good,' Grindelwald required a clear mind and a calm, reasoned perspective.
"Splitting the soul" meant the distortion of humanity and the collapse of reason. He could not accept that price; it ran completely contrary to his ideals.
Grindelwald's sharp gaze pierced Dumbledore's still-blue eyes, and he spoke in a tone of confident statement:
"Is this from him... Voldemort? Or should I say, Tom Marvolo Riddle's Horcrux?"
Dumbledore confirmed the deduction.
Grindelwald's heterochromatic eyes narrowed slightly, and his gaze returned to the seemingly harmless diary.
After a moment, he spoke slowly, his voice low:
"That person has gone too far down the path of the Dark Arts, Albus. So far that... he's practically unmatched."
Grindelwald viewed Dark Arts as a tool—it was efficient, powerful, and very useful at times.
But he never abandoned other forms of magic. He used Dark Arts as his primary focus but supplemented it with other magic, which he used to suppress the detrimental effects of the Dark Arts on his body and mind.
Therefore, compared to Voldemort, Grindelwald was far more "normal."
Voldemort, however, had embraced the Dark Arts with his whole being. His talent in the Dark Arts was already prodigious, and his reckless pursuit of knowledge, regardless of the consequences, meant his mastery in that field was unparalleled.
Dumbledore let out a deep sigh:
"Tom's obsession with immortality was so intense that it warped everything. For him, creating Horcruxes was likely not about seeking ambition or power, but purely for 'not dying' itself. For that, he didn't hesitate to repeatedly fragment his soul, creating such vile artifacts..."
Grindelwald keenly picked up on the key words, a flash of understanding crossing his mismatched eyes:
"So, he created more than just this one Horcrux, didn't he?"
He knew Dumbledore too well.
If it were only a single Horcrux, no matter how sturdy or how rigorously protected, Dumbledore's abilities would eventually find a way to destroy it.
But Grindelwald saw the worry etched around Dumbledore's eyes, and quickly guessed the true problem.
Dumbledore began to explain his theory and concerns.
After that recent "reminder" from young Lucien, Dumbledore felt the possibility of Voldemort possessing multiple Horcruxes was extremely high.
Dumbledore began to re-examine the enormous gap between Voldemort's personality and behavior patterns in his early years and his later life.
The extent to which his rationality was replaced by fury, paranoia, and an incomprehensible cruelty was too vast to be fully explained by simple power inflation or the corrosion of Dark Magic.
"Splitting the soul... and likely multiple times," Dumbledore's voice was low. "That would explain why he transformed into the creature he became later on. But the problem is, we can't be sure how many he made, let alone find them one by one."
"Fortunately, we now have one intact sample. Perhaps it can offer us a clue, point us in the right direction... I have young Lucien to thank for that."
Mentioning that name naturally steered the conversation towards the various events that had taken place at Hogwarts this term.
When the Basilisk was brought up, Grindelwald's eyes flickered almost imperceptibly, as if recalling an unpleasant memory.
Years ago, in an attempt to enhance his 'persuasiveness' with a powerful beast, Grindelwald had also tried to breed that type of magical creature.
However, before the Basilisk eggs could even hatch, he was stumbled upon by a certain perpetually suitcase-carrying young man with an overabundance of enthusiasm for magical beasts.
After a brief struggle, all the eggs were caught in the crossfire and were shattered completely.