A/N: The sin is greed, and the prompt is "five years on". This one's a bit longer than the others. Please review! :)
As he heard footsteps approach his cell, Grindelwald smiled.
"Hello, Albus," he said, without turning to face his visitor. "Have you come to set me free?"
Dumbledore shook his head.
"How did you know it was me?" he asked.
"I know your sound," Grindelwald replied. "Five years ago, I heard those same footsteps coming from behind me before I was stabbed in the back."
"We had been on different paths for a long time, Gellert," Dumbledore pointed out.
Grindelwald finally turned to face his childhood friend, even managing to look him in the eye.
"You're right," he admitted. "But if we're so different, why are you here?"
"I shouldn't be," Dumbledore sighed.
"They are calling to you again," Grindelwald said, with a knowing chuckle. "But what do you need them for? You've already got one Hallow, and they all say you're the greatest wizard in the world."
"What do you know?" Dumbledore asked, ignoring Grindelwald's inquiry.
"Enough," Grindelwald responded. "But there is nothing that you should know, old friend. I realize that now."
Dumbledore gripped the bars of Grindelwald's cell tightly.
"Tell me what you know," Dumbledore ordered.
Grindelwald sighed and moved back so that he could lean his head against the back wall of the cell.
"I do not plan on telling you anything," Grindelwald told him. "It's for your own good."
"The last time that you tried to do something for other people's good, innocent people died," Dumbledore reminded him. "Do not think you know better than me, Gellert. Tell me what you know about the remaining two Hallows."
Dumbledore's hand reached to grip the Elder Wand, and Grindelwald shook his head.
"I cannot help you, Albus," Grindelwald sighed. "Kill me if you want, but you cannot convince me to tell you anything. I know now that men like us should not have such power."
"I am not like you!" Dumbledore thundered, drawing himself up to his full height to tower over the sitting Grindelwald.
"Not yet," Grindelwald corrected him. "You can manage one Hallow far better than I ever could, but it is unwise, even for you, to try to master death."
Dumbledore took a few seconds to calm himself down before speaking again.
"I could change the world," Dumbledore pointed out.
"Do you not remember that I changed the world too?" Grindelwald replied softly. "Power is intoxicating, I know that better than anybody. But Albus Dumbledore, the headmaster of Hogwarts, will improve the world much more than Albus Dumbledore, the master of death, ever could. Do not let greed cloud your great mind."
Dumbledore opened his mouth but abruptly closed it again. For a long moment, he could only stare at his childhood friend.
"Five years has changed you," Dumbledore remarked.
"For the better," Grindelwald agreed. "I am repenting, Albus."
Dumbledore nodded, at last relinquishing his tight grip on his wand. He could not admit that Grindelwald was right, but he needed to gather his thoughts.
"I may come back," Dumbledore declared, as he turned to leave.
"I hope you do not," Grindelwald replied.
"Goodbye, old friend," Dumbledore said.
Not once looking back, he left Nurmengard, never to return.