... taken an unexpected turn?
SPOILERS FOR COWR AHEAD
When I wrote CoWR (and as I still plan on how to continue it), there was a scene with Aomidori becoming evil. When I wrote that, it was on a whim, and when I later read the first chapters I thought, "wow! I actually set this up for her becoming this way even when I didn't originally plan on her being the villian!" LOL. How about you? I have many other examples XD