Developing the Idea for "Forgotten"

     As I mentioned in my first post I'm currently editing the third rewrite of a novel I've been working on for quite some time now. Quite some time being almost 7 years. I first go the idea for this novel, titled Forgotten, when I was in 6th grade. However if you were to compare my draft from 6th grade, to my draft now the only similarities would be the character names (some of which have changed) and the very general conflict of the novel. Back in my first draft my characters were extremely flat. All of them, even my MC, Neona, were essentially boring little emotionless lumps of flesh *shudders*. Maybe if I bury my dignity deep enough I'll dig up that first draft and post some excepts on here for humor's sake.
     It is only now that I'm a Senior in high school that I am satisfied with the characters and the plot. However it is interesting to see how the story has changed over the years. I didn't write in my favorite character, Sawyer, until this summer; and now I can't even imagine how I coped without him before. He's one of those pesky little characters that seems to write himself, no matter what I do. You are probably wounding what this story is about, or maybe not. Maybe I'm severely overestimating the amount that you care. I'll save that for another post, build the suspense a little.

What about you? What is the longest amount of time you have spent writing the same novel?