When a story goes off the rails.

[Logan]

Have you ever had your story mapped out, but just let the story flow as it comes into existence. I have pretty much been a seat of my pants writer, with an idea where it will start and where it will ultimately end, but the meat of the story can take any number of roads to get to the finish.
My current novel, Valqis: The Search, which I am hoping to have ready for release by the end of next month, has had two places where after I had written them, looked at it, and asked, "Where did that come from?" One just appeared when an elf's life was being threatened and he wiped out half a platoon of trained soldiers with the weather. This was nowhere to be seen when I started this process.
Have you ever had a book that has done this?

[Logan]

India, my first off the rails was when my protagonist came home to marry his fiance only to find that she was engaged to someone else.... never saw that one coming when I sat down to write that day.

[Ulff]

If it happens, it happens, screw planning... I started a chapter and due to the music I was listening to, it turned into a slight case of erotica... didn't see that coming... went with it, and that was that.

[Justin]

When I read the title of this one of my short stories, "Horrorglyphics" immediately came into mind. The story is now actually a part of the Detectives of the Fantastic: volume IV but it took some time to get just right.

When I started writing it I had an idea in mind but mid way through I felt that half of the idea I had were going to be way too dragged out so I kind of just came up with something on the fly but then I asked myself where the hell I got the idea as it was completely out of left field. It sort of takes the story out of where it starts but it doesn't hurt it in my opinion just sums it up quicker than if I dragged it out which may have come off as boring.