Who's says to Montag that they are twins and that he wasn't alone anymore?

Faber tells Montag that their twins..... that neither of them is alone anymore.

"Listen. Easy now," said the old man gently. "I know, I know. You're afraid of making mistakes. Don't be. Mistakes can be profited by. Man, when I was young I shoved my
ignorance in people's faces. They beat me with sticks. By the time I was forty my blunt instrument had been honed to a fine cutting point for me. If you hide your ignorance, no one will hit you and you'll never learn. Now, pick up your feet, into the firehouse with you! We're twins, we're not alone any more, we're not separated out in different parlours, with no contact between. If you need help when Beatty pries at you, I'll be sitting right here in your eardrum making notes!"