He needed to be smart, but with a cynical view of the world and a very jaded view of women.
He would need to be placed in a situation where he would be forced to be with someone like her (which normally he would not), get to know her intimately and in dangerous situations, and realize that she was the one thing that would make him whole again: his saving grace. Because of this, Richard became a compelling character in the novel and grew to exhibit his untapped humanity and nobility of character. He was a lot of fun to flesh out.
I wrote the screenplay for this novel and I went to a workshop where I needed to pitch the project. While thinking about how to best explain in a few words about what the novel was like, it came to mind that I could describe it succinctly by telling them that the character of Richard could be visualized as a cross between Rick in Casablanca and James in James Bond, with a lot more from my end.