Carmen was onboard the London Bus Number 200 with the Tenth Doctor and Lady Christina de Souza during Easter time. She was kind to the other passengers and towards the Doctor, whom she warned to be careful after giving him a deadly prophecy. She worried during dangerous or unexpected situations.
Carmen had low-level psychic abilities, which were strengthened by the triplet suns of San Helios. Every week, twice a week, she and Lou won ten pounds on the lottery. She could sense what was going on without seeing it and hear the voices of the dead. After the bus went through the wormhole to the planet San Helios, she warned the Doctor and the passengers that something was coming, riding on the wind, something that devoured.
After the Doctor had saved her and they had returned to Earth through the wormhole, Carmen offered him a prophecy: "...Your song is ending, sir... it is returning through the dark... and ... oh, but then... he will knock four times." (TV: Planet of the Dead)