Have a seat and sit right there, let me tell you about the time Derek Moss didn't even exist in the Kingdom of Walden
At first, the only mention of him was when he was "Steve", which may or may not be the name of the person I based him off of (it is) was during an aborted phone conversation. In fact, the first sign of trouble (ie: the end of civilization as we knew it) was that Terrence's conversation with Steve was cut off because the phones went dead... and then we never heard from poor Steve again.
Flash forward to me having the first draft done, or almost anyway, as I was in the middle of writing it during NaNoWriMo 2012 (yes, After Oil is a NaNo novel!). Steve calls our house somewhat late at night to share the fact that he had managed to sign a pretty fantastic deal (Derek = Steve, remember... completely). Shortly after, he asks the Big Question, which was, "So, what are you up to?"
I answered, and it took awhile to explain it, and he asks if he's in it. I answer that other than for a few seconds, no. He was so upset that he was left out... and I mean really... that he spent a good half hour arguing with me, almost with bullet points, about why he should be there and why it would be realistic for me to add him. I promised him I would include him, but that he could be the "Obi-Wan Kenobi" of the book - I'd kill him off after he trained the protagonists to survive and be the reason they left the Manor. He even argues that he would be a better main character than the one I planned and I really should consider him instead of Terrence.
At that point, I knew I couldn't keep calling him Steve
So, I began calling him David. And, to not use his real name, I changed it to Moss... which made his name go from his real name (which is totally not Steve...
it totally is...) to David Moss.
Oh, and David Moss died of pneumonia midway through the first book.
Cue edits one through three, as David continues to take over more and more of the book... right up until he dies and the reason they leave becomes obvious. Like Obi-Wan, the main characters remember him and that he's the Reason They Left.
And then we get to the great hard drive crash which eats up and spits out my novel into unrecognizable pieces, forcing me to pick up and start over.
It's at this point the betas tell me, "Make David live and see what he's like as the main character of that group instead of Terrence..."
So I did.
Everyone likes David. Edits four, five, and six happen.
I submit it.
The publisher likes the name fine enough, but find that they like David with another character (who would become Zachary anyway) and Derek to become David (which means David Moss becomes Derek Moss instead).
David, wait, no I mean Derek...
Rewrite seven, and another substantive edit... and now you have The Kingdom of Walden as it stands.
The book gets released, and I go to the book signing. Unfortunately, no one managed to tell Steve and he misses it entirely but he, his wife, and I meet up the next day at the Chapters the launch happened at... and that's when he finds out that he told his own future.
Now we're four books, going on five and six, and his character is still the anchor character of the entire series...