Patrick O’Hara — a former TV star with a poolside home in Palm Springs and a closet of caftans — is everyone’s favorite uncle. At the end of Steven Rowley’s 2021 novel, “The Guncle,” Patrick has just spent a summer taking care of his young niece and nephew after their mother dies. The hilarious and heartfelt book became a beloved bestseller — and a movie adaptation is in the works.