Alexa here. I get this question a bunch. In the book Cooper and Me and the First Halloween, Cooper, Trooper, and Bella become good friends by the end of the story. In real life, Cooper and Bella are like typical brother and sister. They fight, steal each other’s toys, chase each other around the yard and sometimes in the house (which is a big no-no but they do it anyway hoping not to get caught), and play games like tug of war. At the end of an exhausting day, Cooper and Bella snuggle on their favorite bed and cuddle--it's very cute. They really do get along in real life!