You are the Chosen One?”
“Of course I am,” said Harry calmly.
“But then . . . my dear boy . . . you’re asking a great deal . . .you’re asking me, in fact, to aid you in your attempt to destroy —”
“You don’t want to get rid of the wizard who killed Lily Evans?”
“Harry, Harry, of course I do, but —”
“You’re scared he’ll find out you helped me?”
Slughorn said nothing; he looked terrified.
“Be brave like my mother, Professor. . . .

Thought we were supposed to be friends? Best friends?”
“We are, Sev.

It is real, isn’t it? It’s not a joke? Petunia says you’re lying to me. Petunia says there isn’t a Hogwarts. It is real, isn’t it?”
“It’s real for us,” said Snape. “Not for her.

But this is touching, Severus,” said Dumbledore seriously. “Have you grown to care for the boy, after all?”
“For him?” shouted Snape. “Expecto Patronum!”
From the tip of his wand burst the silver doe. She landed on the office floor, bounded once across the office, and soared out of the window. Dumbledore watched her fly away, and as her silvery glow faded he turned back to Snape, and his eyes were full of tears.
“After all this time?”
“Always,” said Snape.

The — the prophecy . . . the prediction . . . Trelawney . . .”
“Ah, yes. How much did you relay to Lord Voldemort?”
“Everything — everything I heard! That is why — it is for that reason — he thinks it means Lily Evans!”
“The prophecy did not refer to a woman. It spoke of a boy born at the end of July —”
“You know what I mean! He thinks it means her son, he is going to hunt her down — kill them all —”
“If she means so much to you, surely Lord Voldemort will spare her? Could you not ask for mercy for the mother, in exchange for the son?”
“I have — I have asked him —”
“You disgust me.

Well, you split your soul, you see, and hide part of it in an object outside the body. Then, even if one’s body is attacked or destroyed, one cannot die, for part of the soul remains earthbound and undamaged. But of course, existence in such a form . . .