The dead are hard to look at. Their faces shimmer. They all look slightly angry or confused. they will come up to you and speak, but their voices sound like chatter, like bats twittering. Once they realize you can't understand them, they frown and move away. The dead aren't scary. They're just sad.
Percy Jackson and the Lightning Thief (ed. Penguin UK, 2008) - ISBN: 9780141924403