Daniel Wheldon was the most interesting character to write.
I already wrote about him during NaNo 2011 ('The Revolutionaries') but that story ended up failing completely. I didn't hit 22k, and I gave up. I vowed to do better next year. I knew that I was probably going to fail if I chose to rewrite the darn thing, so that's exactly what I did. Fortunately for me, I was able to actually get to a 50k manuscript! This time the story was a bit of a continuation on last year's idea, and I wrote Daniel as such a character. He was older, he had a backstory, and it made his character very much interesting. Here's the thing: background and context define characters.
If you have invented a past for a character, you will be able to respresent said characters much better. I know Daniel does, and I know a bunch of other characters do as well. Another character I particularily like in this book is Lucas 'Luke' Birkby, who was actually called 'Kirkby' in the 2011 draft. Kirkby sounded too much like Captain Kirk so I changed that up a bit. Anyway, I hope to get the draft to you as soon as mid-2013, but I can't promise anything.