In order for readers to immerse themselves, a book’s characters need to react to the setting. In my futuristic Intervenus series, a cosmic impact shoved orbits of all planets outward by light years. Earth fell into a second Ice Age. When moon-sized asteroids crashed on Mars and Venus, water erupted and morphed their atmospheres into habitable. After Mars’ nuclear war, Venus became the next big hope. The atmosphere morphed into habitable at craters’ lower levels. A group of Europeans arrived two hundred years before, built canals, stocked them with fish, and created a pond with a tree.