Well, a riddle or two in fanfic could serve as a plot device to challenge the characters and keep readers engaged. It could also be used to reveal hidden clues or foreshadow future events.
You might get some brain-teasing puzzles that add an element of mystery and intrigue to the story.
A riddle or two in fanfic can bring an element of surprise and make the story more interactive. It might force the characters to think outside the box and showcase their problem-solving skills.