Kill off your main characters. Please. Not
as a cheap ending, or right at the
beginning for shock value. Kill them in the
middle, and do it well. Leave every
character reeling and unable to
comprehend what happens next. Leave
your antagonists without a solid enemy,
wondering if they've gone too far.
When you shatter the heart of a story, a
thousand tiny shards will spilt away and
grow. Focus on the side characters; the
supporting cast, the love interest. Think
about how they would change, break and
reform. Think about the growth, the quiet
moments of reflection and depth.
You don't have to do it, but think about it.
If your story stops with a single character,
your story is weak.
Kill the protagonist.