The good guys had to operate on a higher level than the killers--just for society to keep track of who was who.
Sometimes when you push someone, you find out who that person really is.
Relationships are never chance events.
When people can do something simple to avoid conflict--say, hit a button or unlock a latch--they'll generally do it.
People react predictably, especially when they don't have time to think.
Plenty of people who survive tragedies end up ambivalent about danger--frightened by it, yet strangely drawn to it.