Ah, the dictionary is a lovely thing... as a starting point for a post, a definition is hard to beat (and apparently Michael agrees with me, as you'll see when you read his post about "flashpoint" from yesterday).
Now, here are the two definitions that popped up on my screen, thanks to Google:
- a place, event, or time at which trouble, such as violence or anger, flares up.
- the temperature at which a particular organic compound gives off sufficient vapor to ignite in air.
In fiction, writers rely on emotional flashpoints all the time to justify a twist in action, character, and motivation. They often provide a kind of "tipping point" or point of no return.
You can use an emotional flashpoint to propel a character into doing something incredibly stupid, such as (imagination at work here) having your protagonist chase the theoretical killer down a dark alley in the middle of the night. With no flashlight. An an empty gun. And no backup.
Or, a flashpoint can bring out the sudden (and perhaps unexpected) noble and courageous side of a character, such as maybe the theoretical killer's father--who is the REAL killer--is waiting at the other end of the alley for his daughter to arrive. He hears the protagonist shout "Stop or I'll shoot!" sees the gun come up... and jumps forward to push his daughter out of the way and take the (theoretical) bullet in her stead.
Oh, I said the protagonist's gun was empty, didn't I. Hmmmm. I'll leave it to you to ponder what might happen next.
Or, you could go with the second definition of flashpoint and have fun with flammables... let there be light in that dark alley!