Harry Potter and the Order of the Phoenix2007

[about the thestrals]

Harry:
So why can't the others see them?

Luna:
They can only be seen by people who've seen death.

Harry:
So... you've known someone who's died?

Luna:
My mum. She was quite an extraordinary witch, but she did like to experiment, and one day one of her spells went badly wrong. I was nine.

Harry:
I'm sorry.

Luna:
Yes, it was rather horrible. I do feel very sad about it sometimes. But I've got Dad. We both believe you, by the way. That He-Who-Must-Not-Be-Named is back and you fought him and the Ministry and the Prophet are conspiring against you and Dumbledore.

Harry:
Thanks. It seems you're about the only ones that do.

Luna:
I don't think that's true. But I suppose that's how he wants you to feel.

Harry:
What do you mean?

Luna:
Well, if I were You-Know-Who, I'd want you to feel cut off from everyone else. Because if it's just you alone, you're not as much of a threat.