Because I knew he wanted to go die.
He did not care how he died. We could stop him from dying that way, but we could not stop him from killing himself out in the wilderness while we were not paying attention.
So, I let him go.
Besides, I was also worried that he would not bear to kill Voldemort..."
Dumbledore hesitantly voiced his thoughts.
Harry stared at him in shock.
"How could you think that?"
"I was not merely guessing. I never imagined that Tom had truly come to feel love.
I do not know when it began, but Tom had already started valuing Darren more and more.
I thought it was just my imagination, but once, when I instinctively used Legilimency on Darren...
Yes, that was my despicable side. I cannot deny it.
When I used Legilimency on Darren, I discovered that one of his memories had been altered...
I went to great lengths to finally extract that memory from his mind... Perhaps, Harry, you should watch it with me.
That memory made me question Darren's origins. It was only after learning of it that I felt I could not let Darren face Voldemort!"
Dumbledore's eyes were red as he took out another small glass vial.
He poured the silvery memory inside into the Pensieve.
Harry was brought into it.
He saw Voldemort fighting Darren.
Dumbledore explained from the side, "This was when Darren was in fifth year. I sent him on a mission, and he encountered Voldemort... They are fighting now. Watch Voldemort carefully."
Harry watched Voldemort continuously wave his wand, a vaguely amused expression on his face.
As he watched, he suddenly cried out, "Voldemort is holding back!"
Dumbledore nodded.
"Yes. Voldemort is holding back. He did not use the Killing Curse, nor did he use