Or: Writing for Stress Relief.
You see, I'm a murderous person. (I'm sure those that have read my Hunger Games fan fictions will be shocked by this revelation.) My "backup" career choice is based on my fascination with how people die.
At the same time, the Bible says murder is a no-no. I'm not going to get all of the schooling necessary for medical examiner-dom anytime soon, either.
The only instantly-gratifying, bloodthirst-satisfying solution, then, is killing people who don't exist. It's also great for stress relief.
For example, let's say I'm extremely upset with people who travelled long distances to Oklahoma in order to rob the people who had lost their homes, limbs, and/or elementary-age children to the recent tornadoes. So I write a story where some fictionalised versions of these thieves engage in such matters and either meet their terribly gruesome deaths or head home only to find their houses have been destroyed in one of the wildfires in Colorado. Or both. Yeah, probably both.
Of course, I do my share of killing off perfectly innocent characters as well. It's just whatever I feel like doing at the time, whatever would help blow off steam. That's the magic of writing—I can do whatever I want to these characters, and it will never be wrong. It might even be enjoyable or helpful to some people.
Do you like to get away with murder in your stories? What else?