Time travel novels were a common form of literature. They often told stories about the protagonist traveling to the past or future worlds to experience various adventures and challenges. The following are some common plots about time-travel novels: 1. The protagonist travels to the future or past world and returns to the present through technological means or other means. 2. The protagonist transmigrated to a historical event to become a historical figure and experience the adventures and stories related to them. 3. The protagonist travels to the future and discovers that he is the guardian of the future and takes risks for it. The protagonist traveled to the past to become a member of a family and experienced various stories and adventures in this family. 5. The protagonist travels to another parallel universe to explore and interact with other characters. Time travel novels often involved concepts such as time travel, time travel, future technology, historical events, and parallel universes. These concepts could be expressed in various forms in novels, such as science fiction, fantasy novels, horror novels, and so on. Time travel novels are very popular among readers because they allow people to go back to the past or the future to experience different cultures and history. At the same time, they also allow people to explore their inner world and life goals.