A/N I don't own this. I just wanted to try to explain some of Dumbledore's actions.
"Sir, can I tell this to Ron and Hermione?" Harry asked cautiously. The memories were one thing, but Horcruxes were something else. He trusted them, but he would understand if Dumbledore wanted him to keep it to himself.
"Miss Granger and Mister Weasley are very good friends, Harry, but I'm afraid I'll have to ask you to keep this to yourself. Horcruxes are even more dangerous than you think, my dear boy."
"Tom is afraid of dying, which enabled him to do anything that was necessary to prevent his inevitable death, but Tom doesn't know all there is to know about splitting his soul."
"Sir?"
"I trust that you know about the war against Gellert Grindelwald?"
"I have, sir. You defeated him in the same year muggle World War II ended. He is now a prisoner in Nurmengard."
"Indeed. In that war, Harry, he had as many – if not more – followers than Voldemort. The battles raged on, muggles, wizard, squibs, all of them started dying. There was no day that there were no deaths in the Daily Prophet. We were eventually forced to kill."
The old man stood and walked to Fawkes' perch. He started petting the magnificent phoenix and silence filled the room.
"Sir?" Harry asked.
"Yes, Harry?"
"Did you ever…?"
"I've killed, Harry. It is something that makes me disgusted with myself. I took the life of men and women to save those that were fighting on our side. Mothers and fathers, daughters and sons. We all did. I doubt that there is one witch or wizard in my generation that didn't commit that horrible deed."
"I've killed too," Harry admitted. "I've tortured."
"Professor Quirrell was dead the moment Voldemort decided to posses him. You did nothing wrong, my dear boy."
"How can you say that? I killed a man, I hated a woman enough to torture her. I wanted her to…," he trailed off.
"You wanted her to suffer. In a moment of rage, you lost your control of your magic. It's nothing to be ashamed of Harry. Hate is an emotion too. Love cannot exist without its opposite. If hate didn't exist, love would lose its meaning."
Harry sighed and let the matter drop. You couldn't win this kind of argument from Dumbledore.
"That was not what I wanted to say however. In that war many have committed the sin of murder, Harry. They have ripped their soul apart. If anyone gets the knowledge of Horcruxes, we have many objects lying around."
"But why would they do that?" Harry asked, confused.
"You Harry, who has never known how not to love, won't understand the simplicity of immortality. If your soul has been split already, and you feel no remorse for killing someone that would've harmed your loved ones, you can make a Horcrux. There are books about the subject that will fall into the wrong hands, and soon it will become public knowledge. Noone would die."
"I trust Hermione and Ron, though," he defended.
"And I, Harry, trust no one but you with this information, not even myself."
"Sir, did you make a Horcrux?" Harry exclaimed.
"Even I have contemplated the idea of immortality, Harry. I do not fear death, but I am nearing my death. I'm an old man after all. I feel that I'm needed in this war sometimes, and I can be if I make one Horcrux with a murder I've already committed."
"But Hermione and Ron have no reason to, I can tell them."
"Tell me, Harry, what is it that Miss Granger likes most?"
"Books," was his abrupt answer.
"There are many books in this world, most she will never have the time to read. So if she could just give herself a little more time, would she do it? She only has to say in incantation after all."
Harry looked surprised at his mentor. Hermione would never do something like that, would she. She would never commit murder for the purpose off creating that which they want to destroy. But she had probably already committed it by the time the war ended. Only that simple incantation in Latin and a pretty necklace and she would be able to read everything she wants to.
"I could tell you something similar about every student and Professor in this school. Even Miss Lovegood and Mister Longbottom would give in if they thought that a few years extra would allow them to find a cure for Alice and Frank and some creatures that have yet to be found."
Harry knew the headmaster was right. He would give anything to get his parents back, and Neville would too. He could start thinking of reasons everyone he knew would create one, given the chance.
"I've suspected Horcruxes for a while now, but I couldn't tell anyone in fear of their surrender to their own desires. I don't trust myself with it, and I'm afraid to trust anyone but you with this knowledge," Dumbledore confided.
"I have unofficially been appointed as leader of the war. I know things that others need to know, but I can't tell them. I've sent members of the order to capture or kill a Death Eater that had taken one of our own. Voldemort forced my hand and I saw a wife kill her Death Eater husband in cold blood, and see her scream and cry when she saw his face. I knew who he was, but I couldn't tell her. I'd hoped to let her belief that her husband died in a duel and heroically. I could've spared her so much pain, but I couldn't, because they wouldn't have done that to their friend."
Harry sat in his chair silently as he contemplated what he had been told. The choices the man made had been hard on him, but he was willing to do it again because it was the right thing to do. Many hated him for it. For his manipulation. For keeping his plans and ideas to himself. Harry couldn't imagine having to make those decisions.
If Dumbledore had to choose between three woman and one child, his choice would always be viewed as wrong. Whether it be the parents of the child, or the spouses of the women.
"And the prophecy?"
"I told your parents and Alice and Frank because they deserved to know. They loved both of you very much, and your mother was far too suspicious. She'd never do something without a very good reason. But we didn't tell your Godfather or Remus. If someone told Voldemort the prophecy, on purpose or not, it would've ended right there. Tom would overpower me, and without you, the Wizarding world would've crumbled at their feet. "
"I'm sorry to have burdened you with this task, my boy. But there is noone that I would trust more with it than you. I am proud of you, Harry, and there is not a single doubt in my mind that your parent are too."