there is always something that isn't in there that informed the writing but doesn't matter to the plot so isn't on the page.
Do you consider those things to be part of the story, or not? I know what you mean about unseen things informing the story - I had to know exactly what a character had been doing in the war, although only his uniform made it onto the page - but I don't think of them as being part of the story as such. It's intriguing, and those are the things that sometims spawn sequels/prequels/monster-ficverses-that-you-didn't-mean-to-write.