Rereading for details: the kids ask why Bob has a cast in only this picture. I told them I'd ask the author. They didn't believe me. I messaged him on Instagram, and he got back to me within the hour. "Bob has gout, a build up of Utica (sic uric) acid in the joints of his foot. It's from a diet of very rich food. It was referenced as '"The disease of kings'" because only the wealthy class could afford such culinary luxuries."