So, all yesterday and all today, I've been going through google images, which is harder than it seems. Most of the faces I'm seeing look too pretty, or too posed. There isn't the roil of inner lives in the faces. I even went on match.com (I told my husband beforehand that it was just for research) to scan faces, but those, too, seemed too posed, too anxious, or simply not right. I wish I knew a better way to search for the really interesting photos where people are in action, revealing themselves.
But I'm not frustrated. I know I'll recognize my characters the moment I see their faces, and all I have to do is find them.