to other "one-off" companions like Astrid Peth.
He walked away into the shadows of the tunnel, a lonely traveler with the dust of a dead world still on his shoes. Key Takeaways from "Planet of the Dead" [S0E13] Planet of the Dead
She didn't hesitate. She handed over a necklace of psychically-responsive crystals. The Doctor jammed them into the steering column. to other "one-off" companions like Astrid Peth