An Author's main role is something of a fallacy to many people who don't write. To many it seems like a novel's contents are based on the whims of the author, or is, in a good friend's terms, "your world on demand." This is a big misconception.
It is, indeed, an author's role to create the setting, plot, and characters of the story, but the story's path is as unpredictable as our own lives. Our original ideas provide only the backbone to what will originally develop into an organism of many systems.
When a writer starts to write, it is an awkward step, like stepping into cold jell-o or giving yourself a pelvic exam. But as the writing utensil makes its lines and arcs and dots, it gets easier. Soon the author is submerged in their own ideas, their own world, and the utensil seems to almost write by itself. Words fly out onto the page, words and ideas that never occurred to the author. Perhaps it is the subconscious. Perhaps it is the Hand of God. Who's to say?
In the beginning, the characters are created and brought to life. But as soon as that vitality is breathed into them, they start to dance. They dance together, alone. They are not marionettes. They are not hand puppets. An author is more of a director than a puppet master; they write the words and steps, but the characters dance it out and, in doing so, provide their own grace and their own technique.
Oftentimes, as a story is written, many of the author's original ideas are metamorphosed or cast aside completely, just as our plans are in our lives. Novel-writing is as unscripted as our own lives are. Often an author must edit their ideas around the character's steps. Mostly a story works itself out to be drastically different than the original plan. Most times the change is positive.
An artist's example:
Sketch something; it's very structural and basic, right? Now spend a year or two making a masterpiece out of your sketch. You'll find that the end result differs massively from the original sketch.
No one can predict the outcome of the story. One can make a guess, or plan for an outcome, just for completion's sake, but no one knows what the ending will really be. The characters get up and dance. An author only records their steps, speaks for those who cannot speak themselves.
For some professional word…
Famous Horror novelist Stephen King would agree. His series, The Dark Tower, started when he was just 19. The manuscript for the first book, the Gunslinger, sat in his garage in a box until his mid-thirties, I believe, until he started work on it once more. He had no idea what the outcome of these novels would be; after the third book, the Waste Lands, he got two letters. The first asked for the outcome of the novels, from a man on death row. He told King in the letter that he would "take the secret to his grave." Despite his desire to indulge, King could not; he did not know himself. The second letter was from a woman dying of a brain tumor, by the name of Coretta Vele. On the subject, Stephen king says, "They think I'm in charge, every one of them from the smartest of critics to the most mentally challenged reader. And that's a real hoot. Because I'm not." (The previous information can be found in the afterword of the sixth book, Song of Susannah, by Stephen king. The quote is from the entries of his journal featured there.)
On the contrary, another quite famous author, Christopher Paolini, author of the Inheritance series, says that, at 15, he had the entire outline for the series out on paper, and wrote the entire tale accordingly. (According to the interview in the extra features of the movie eragon.) His own published books discount his claim. In the first two books, the back says to stay tuned for the next book in the Inheritance trilogy. However, he is now finishing the tale in the fourth book.
Author J.K. Rowling also said that she knew the outcome of the world-famous Harry Potter series, that it was "locked in a vault somewhere in London." This may be true, but upon its resurfacing from said vault, I'm willing to bet that it had a good deal of change.
I just wanted to clear up a common misconception of an author's ability to "play God." They do invent the basic backbone of the character's fate, but the characters are also prone to their own whims. Authors are indeed inventors, but most of the work is character-to-reader translation. It's like childbirth: painful, stressful, and difficult, but more than rewarding.
As a huge fan of Stephen King's work, I highly recommend the Dark Tower series. Just a few words of advice to those who decide to embark upon that journey:
Have the next book handy as you finish one. The wait between books is enough to drive one crazy.
Bear with the ending of The Waste Lands; as long as you have the next book handy, that is.
Happy writing (and reading)!