Your character has been kidnapped!
What is his/her first reaction? Is it a scary situation or just confusing? Maybe it was a pleasant aside that turned sinister, or maybe your character knows the kidnapper and doesn’t even realize what is happening?
Try to create a beginning, middle, and end to the situation…if it ends. Does the character lose his/her identity or sense of what is real? Does s/he dream about her “real” life? Does your character try to escape? How?
Or…switch it…
Your character has kidnapped someone! Who? Why? What happens?
Even if you don’t use this writing exercise in a story, thinking about your character’s reactions and choices can really help shape them into a more “real” entity with a better-defined personality. And, if you can really take yourself into such a scenario, you might just have a new story on your hands! Good luck!