Fiction: what is reality, anyway?

I still don’t have a definition of “fiction” that covers all the territory, but I have discovered (!) that published stories aren't always fiction.  That's another duh for me.  I mean...

...take a look at The Wild Trees, by Richard Preston.  It came out in 2007 after its meaty core about the tallest redwoods appeared in The New Yorker.  That book would never have hit the New York Times bestseller list (which it did) except that Preston, in naming the discoverers of the tall ones, turned the men and women into three-dimensional characters with goals, problems, virtues and faults.  Like in fiction.

Gavin Menzies, in 1421, The Year China Discovered America, (2003) did a similar thing.  In fact, his book is written a lot like a mystery novel and reveals history one clue or episode at a time.  It was another best-seller.

And then, consider some terms we use about fiction: novel,‭ ‬novella,‭ ‬short story,‭ ‬ flash,‭ ‬playscript,‭ ‬video/movie script,‭ ‬graphic novel, narrative poetry.  Each genre concerns a made-up story, right?  So what did Menzies and Preston make up, and why did I eat 'em up like candy? 

Because I was involved in the, er, story.  Because the characters seemed real and their goals interested me.  Because the settings were exotic.  Because the writing was good. 
 
As I remarked before, Ralph Waldo Emerson wrote, “Fiction reveals truth that reality obscures.” He might have said the same thing about poetry, but maybe the whole argument, about genre and its relevance, is beside the point, and maybe his claim is the best definition.