"[Melinda Gates] is a lot of fun to work with. There's some of the people skills that she's better at and cares about more. It'd be a mistake not to think of her as very numerical and interested in the science. I enjoy, if I get ahead of her, say, understanding the immune system, then we can spend a few hours, where I'm going through how amazing it is and interesting, and how that affects our creating new products, so I've always had a partner."