When I write, I find it really helpful to find real people to "play" my characters while I'm spinning the story in my head. Sometimes I base them on pictures I find in magazines, but in most cases I cast an actor or another well-known personality, and incorporate some of their quirks into my characterization. It helps the characters come to life for me, and makes it easier to write about them.
In this post, I talked a little about how I tuned in to the character of Evgeni. It was finding my Evgeni that got this version of the story moving along. But I also had to find Anna before I could really get underway.
Anna was a shakier process. Originally, I had pictured Faith from Buffy the Vampire Slayer (Eliza Dushku), but as the story changed into its current form, that didn't quite work. While I was doing my initial work, the news arrived that Elisabeth Sladen had passed away. Elisabeth played Sarah Jane Smith in Doctor Who back in the 80s and also in some of the more recent incarnations of the show. She was the first companion I saw, when I started watching Doctor Who with Tom Baker's first story, "Robot," back when the original series was being broadcast on PBS.
Right away, I wanted Anna to be a sort of tribute to Elisabeth Sladen. But she herself didn't quite work for me in the head canon of the role. I named Anna Slaten in her honor (yes, I changed it a little--it just seemed like the right name for Anna although, as an aside, for some reason I kept also calling her Stanten, and had to weed out those typos in the last few drafts), and then started looking at other Doctor Who companions to fill her role. I tried Karen Gillan for a while, but that didn't work. Finally, while I was catching up with some episodes, I hit upon "Planet of the Dead," and the one-time companion Christina, played by Michelle Ryan. She was a kickass type who liked to wear black, and she immediately felt like the right face to put on my Anna Slaten.
I also "cast" Delgrado. This was a strange process, because I had him pictured very clearly in my head, but then couldn't place the face of the actor who had taken him over (this isn't the first time this has happened...). Finally I realized he was Clark Gregg, Agent Coulson from the Marvel movies and now Agents of SHIELD.
You can take a look at all my "casting" photos as well as some other research materials I used for the book on my Pinterest account. And please take a swing by my Kindle Scout page and drop me a vote!