You eat like a bird.
You'd know of course.
- Psycho

Tony Perkins runs up to the old Victorian house on the hill, and from Janet Leigh's perspective, we see the old house and we hear voices coming from inside.
"What are you so happy about, Boy?"
"Nothing, Mother. She's lost."
"And you're the one to show her the way? What do you know about the way, Boy? She'll not be appeasing her ugly appetites with my food, or my son." And when the voice says, "I refuse to speak of disgusting things," what it's referring to is desire.

He brings a tray of a bread and butter down to the motel, and they sit in the parlour. His hobby is taxidermy and the walls of the parlour are filled with examples of his handiwork. She looks around at the stuffed birds.
"It's a strange hobby," she says. "Curious."
"Uncommon too," he says. "And not as expensive as you'd think." And as he fondles one of his glass-eyed birds he says, "It's more than just a hobby." He's not shy talking about his birds, or about his mother. "A son," he says, "is a poor substitute for a lover," and this is when it dawns on Janet Leigh that Tony might be slightly mad. He's nervous and fidgety, constantly sucking on pieces of candy; but he's also lucid. "We're all in our private traps," he says. "We scratch and claw, but only at the air, only at each other." And in talking to him she realizes that she's stepped into her own kind of trap, and she decides then to return to Phoenix, to take the money back and face her life. ... or...