Here are some helpful tips from Charles Yallowitz on adding fear to you writing.
Even if you don’t write horror, you may want to include some fear in your stories. From fear, we can create hope and relief. We can also drive people into despair and sadness. It’s a fascinating jumping point for so many stories. Yet, one does come off a little depraved if they enjoy the manipulation too much. Still, we’ve come this far (5.5 sentences) and might as well move on to the advice.