Harry Potter and the Deathly Hallows
And Dumbledore had known that Harry would not duck out, that he would keep going to the end, even though it was his end, because he had taken trouble to get to know him, hadn't he? Dumbledore knew, as Voldemort knew, that Harry would not let anyone else die for him now that he had discovered it was in his power to stop it. (34.7)
"I am sorry too," said Lupin. "Sorry I will never know him – but he will know why I died and I hope he will understand. I was trying to make a world in which he could live a happier life." (34.57)
"But…" Harry raised his hand instinctively toward the lightning scar. It did not seem to be there. "But I should have died – I didn't defend myself! I meant to let him kill me!"
"And that," said Dumbledore, "will, I think, have made all the difference."