Plot twists

As a reader, I rarely critique basic storylines, saying, "Well, I would have done this if I had been writing the story." I take it for granted that the characters have minds of their own and that the author is just telling their story.
The funny thing is, as an author, I find that to be just as true. Oh, I can change things, of course - especially when the story's stalled or feels off somehow. But usually all I do is change the circumstances, the situation. Then the character "reacts" and ZOOOOOOM! The story is telling itself again.
I just finished the rewrites on Troubled Skies, for example. I had originally written it so that a particular character is very mysterious, appearing almost out of nowhere. But it didn't feel right. It felt too...melodramatic, I guess. chuckle - To my surprise, as I reworked the prison break, I found myself inserting a hint of the character here and there. Poof! He was part of the story, equally mysterious, just not appearing, so to speak, out of a blinding flash and a veil of smoke (think Las Vegas magician).
And I've dumped a whole new problem in my lap, because that's more or less where that story trails off. Now I've got to write the next story to figure out his background, his interaction with the rest of Fairydom, etc.  Believe me, plot twists can be just as surprising to the author!