Sometimes you reach a point in a story and you can’t figure which way to go. Sometimes, oh allergic to writing things down pantsers, we forget what was supposed to happen, after a hiatus. Sometimes we read a blog that decries our choice we haven’t even written. Sometimes we have too many ideas.
If you can’t remember what your plot was, the grim reality is that if you can’t recover it through meditation, free-writing, or hypnosis, it’s gone. Take the pieces you have and make a new plot, cursing all the way, because we always know that the one that slipped our minds was just fabulous. Except it probably wasn’t or we’d remember it. It probably just seemed clever at the time. Very often, after you’ve written a new version, if you find the steno book or disc with the missing plot notes, you find they’re just so-so and you’ll be happy with the new one.
If the markets and your ideas conflict, you will discover one of two things. Either you are the kind of writer who can enjoy working to plan and modifying your ideas to suit — you lucky dog! — or you are the kind who is stuck writing what you have to write. (This does not excuse bad plots, junk characters, or derivative settings as being what you “have to write.”) What you will likely find is that after you have written one complete draft, you can put that away as “the true story.” After that, you can write “the fictionalized version” and feel free to modify it any way it needs to go. That, or you may find that you were thinking of the wrong market for this, and it’s really some other genre.
Sometimes you reach the middle and you know your ending, but you just can’t decide by which road to get there. Sometimes you reach a point in the manuscript where you realize that, at this point, you could go for one of two endings, either of which is good. Or a character could be one of two things. In all cases, both are good — it’s not like one is soggy or undramatic or unsatisfying — but it makes it a very different book.
Worst of all is when the character, as you’ve been writing, has revealed itself to be something you’re not sure would be in some planned plot situations. Even though you had been decided on the plot, the character has made it all questionable.