I love being able to slowly peel layers off these characters. I adore Eve and Roarke, and the rest of the characters. I have tremendous fun with the setting, making up the new toys. I don't think there's anything about writing the series I don't love. I believe people are fairly constant.
Certainly emotions are.
Love, hate, greed, courage. But the toys change. In these books, I've more or less created a world. I have to see it, create the rules as well. Then I have to stick to them.