  Fear is a universal concept; people crave it in urban legends, scary movies,
and modern stories. Open questions remain, however, about why these stories are
scary and more generally what scares people. In this study, we explore these
questions by analyzing tens of thousands of scary stories on forums (known as
subreddits) in a social media website, Reddit. We first explore how writing
styles have evolved to keep these stories fresh before we analyze the stable
core techniques writers use to make stories scary. We find that writers have
changed the themes of their stories over years from haunted houses to
school-related themes, body horror, and diseases. Yet some features remain
stable; words associated with pseudo-human nouns, such as clown or devil are
more common in scary stories than baselines. In addition, we collect a range of
datasets that annotate sentences containing fear. We use these data to develop
a high-accuracy fear detection neural network model, which is used to quantify
where people express fear in scary stories. We find that sentences describing
fear, and words most often seen in scary stories, spike at particular points in
a story, possibly as a way to keep the readers on the edge of their seats until
the story's conclusion. These results provide a new understanding of how
authors cater to their readers, and how fear may manifest in stories.
