I agree that you never really know until it happens. When I was 13, I woke up about 6 am to find a drunken stranger sitting on the edge of my bed. Being the extremely shy, anxious kid I was at the time, I would have been sure that I would have panicked at the very least. Instead, I sat up and talked to him for close to an hour before he finally looked away for a minute and I ran out the door to get my mother up.
Long story short... we lived in a lower duplex and my bed was in front of the door that led to the inside door to the upstairs. He had just gotten out of prison (for assaulting his mother), and was there to kill his ex-wife who lived upstairs. My mother was a basket case, and kept telling me I should have screamed. About 7 that night, I had a brilliant thought and said to her "Maybe it's a good idea that I didn't scream. He had to have a knife if he cut the screen to get in." We found out later that he had also broken into the sporting goods store around the corner and stolen a gun and ammo.
I really do believe that if someone were to pull a gun on me today and tell me to get into his car, I'd probably just tell him that he might as well shoot me because I'm not going with him. Of course, I also believe that I'll never know if that's true or not; I'm forever the optimist!