" Douluo " was a famous fantasy novel in which the main character's starting age was 100,000 years. However, there were some unwritten rules in the novel. Here are a few of them: Protagonists usually have unique personalities and characteristics that will affect their destiny and growth. The protagonist usually plays an important role in the story, with complicated interpersonal relationships and growth experiences. The protagonist will usually experience some difficult challenges and tests such as combat, magic, social and political struggles, etc. Protagonists usually have powerful abilities and special skills that can help them defeat powerful enemies and solve difficult problems. The growth of the protagonist is usually accompanied by various accidents and surprises, which will affect their character and fate. The protagonist usually encounters all kinds of complicated characters and plots in the story. They need to constantly think and respond in order to grow and move forward smoothly. These are some of the common unwritten rules in Douluo. These rules reflect the complexity and richness of the novel's plot.