Mark Ruffalo

I was an introverted kid; I liked my time alone. And the rest of my family is pretty extroverted, so I felt like a bit of an oddball. They're very gregarious and charming and charismatic people. I always felt like I was struggling as a young person. I think everyone was very surprised to hear that I wanted to be an actor.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.