How to Avoid Death in a Book

The characters aren't real enough. They have just enough roundness to them that you feel bad when they die and no more than that. And so that is a cue to you that their purpose in the book will be to make you sad when they die. If they die, people are sad, but you know that the plot would still succeed. So I actually think that planning something that is longer so that you can see the arc and when it is cut off short, it comes as a surprise. It tricks the reader into investing in that character and arguably works much better because they're invested in a different way.