- Billie: It's over.
- Sam Winchester: What's over?
- Billie: You and Dean, dying and coming back again and again. The old Death thought it was funny. But now there's one hard, fast rule in this Universe: what lives, dies. So the next time you or your brother bite it, well, you're not going to Heaven or Hell. One of us - and, Lord, I hope it's me - we're gonna make a mistake and toss you out into the Empty. And nothing comes back from that.