Tip #271: Backstory & plot

your protagonist should have an emotional backstory that enhances or complicates the plot of this book now.

Given example:

If he’s falling in love in the plot: What has his experience with love been like before this?

http://thewholemegillah.wordpress.com/2012/03/13/second-sight-an-interview-with-executive-editor-cheryl-klein/

This backstory tends to be one of the reasons why this story could have only happened to this person in this way.