Here's a simple rule:

If you bring your audience into darkness, bring them back into the light.

Not every story has a happy ending, but it should at least offer a worthwhile lesson.

If everybody in your story loses and there's no silver lining, your audience loses, too.

Stories affect how we think and how we feel.

A dark story can leave the whole room feeling depressed or angry.

Even holocaust survivors tell stories about small victories, small ways they were able to fool their captors, and miraculous moments when they were able to smile despite their circumstances.

Don't ruin your audience's day.

If you bring them into darkness, bring them back into the light.