Grindelwald studied him for a long time.
"You're afraid, Albus," Grindelwald said, sounding surprised. "Is it because he reminds you of me, or because you're afraid he'll become like me?"
Dumbledore did not deny it.
He took off his glasses and slowly wiped the lenses with a corner of his robe. The gesture made him look terribly old, terribly tired.
"I once believed I could guide Tom," he said quietly. "I believed I could show him a path beyond power and fear. I failed. We both know how much suffering and death that failure caused."
"Albus," Grindelwald said, "you're a hundred and thirteen. I'm not far behind.
We belong to the last century. We were shaped by an age of upheaval in the Wizarding World. Our paths, our pride, our mistakes, our redemption... all of it belongs to that age."
Dumbledore put his glasses back on and said nothing.
"But that boy belongs to this age," Grindelwald continued. His gaze seemed to pierce through time, looking toward the distant past.
"Yet human weakness is eternal," Dumbledore said, bitterness edging his voice. "The hunger for power, the desire for control, the arrogance of believing one can make 'better choices'... none of that disappears when the times change."
Grindelwald shook his head so slightly it was almost imperceptible. "You're right. Human nature is eternal.
But it takes different forms. Tom Riddle wanted power for its own sake. He wanted to rule through fear. He wanted to escape death.
"And we..." He paused, something complicated flickering in his eyes. "We once wanted to use power to create a new order, one where wizards need not hide and could freely lead the world. We both believed we were right. We both believed our path served 'For the Greater Good.'"
He looked straight at Dumbledore.