Rose: I thought it was a warning… maybe it’s the opposite. Maybe it’s a message. The same words written down now and two hundred thousand years in the future. It’s a link between me and the Doctor! Bad Wolf here… Bad Wolf there!
Mickey: But if it’s a message, what’s it saying?
Rose: (already running off) It’s telling me I can get back! The least I can do is help him escape!
Doctor Who - 1.13 - The Parting of the Ways