When I decided to write Dream Duology, it was meant to be two books (hence Duology), but I thought I would separate it to five, and then four, books. Then I decided it really should be two books.
This was based on a story idea I wrote back in high school or early college time. Revenge was about five pages of the very short story that wasn't fleshed out at the time. I had a second story called The Princess, The Traitor, and the Savior that I wrote in high school. I used this story to help determine more ideas (Alan training her for a number of years was from this second story).
I went through various names for Dariel, starting with Najod, but eventually settled on Dariel. I when I came up with Morca's dream world name, I came up with the name for her magic.
I wrote book one after I wrote book two because I love the second book more than the first. However, I ended up very happy with how the first ended up as well.