Consistency

I love stories that show imagination, those plot lines that stretch the boundaries of what we thought possible.  However, within that universe, the general story itself must be consistent.  No, I don't go around and nitpick every little detail to ensure it shows continuity from the previous incarnation, but those that are wildly off the mark draw my attention and have the potential to ruin my enjoyment.

We find comfort in the worlds that writers create.  We get wrapped up in our favorite characters, and while they provide an escape, they also provide a sense of security in an otherwise inconsistent world. As characters and worlds grow on us through the course of a novel or a series, we come to expect certain things.  Within an acceptable range, the people in our stories react and interact in a certain manner, and it adds to our buy-in.  The worlds created by a writer do the same thing - we envision ourselves on the steppes of Vallenia, riding along with the Tugar Horde, or picking our way through the Enchanted Forest with Hagrid.

However, when these things do something out of the ordinary, it throws us off and disrupts the flow.  A little surprise is exciting, but that surprise needs to make a certain amount of literary sense.  It would make no sense for Jack Ryan to suddenly be an Asian woman with a penchant for knitting or for Robert Neville to wake up in the middle of a bustling metropolis.  Such deviations make a story silly as opposed to wondrous.

This problem manifests itself the worst in sequels, usually by ignoring the story's history.  In the original Zorro - The Curse of Capistrano - Johnston McCulley was so inconsistent that it makes reading the anthology as anything but a series of independent tales pointless(Captain Roman dies at the end of the first story and Zorro is revealed to be Don Diego Vega, but the books afterwards, such as The Tales of Zorro, ignore this, leaving Roman alive and Zorro's identity still secret).  This can be maddening as we get invested in a novel, only to have later works supposedly set in the same world show wildly divergent themes, thus ruining what we thought the novel was about.

To a certain extent, this can be understandable - an author has to keep the history of his or her world in mind while writing, and they usually do this from memory(yes, some have elaborately detailed arcs that are meticulously written out on poster board, but that is rare).  However, maintaining a semblance of order is one of the things that keeps us as readers sane.  We want to be thrilled and challenged, but usually within a set of boundaries.  Writers that brazenly ignore these boundaries risk alienating their audience. A person might slam down a book, so mad that they vow to never read that author again.  When that happens too often, a writer might as well shout his or her stories into the wind, because that's about the only thing that will listen.