As the internet grew, it served its function and people gathered on sites to express common interests. On one of the most interesting sites on the internet, Tumblr, people excitedly chatted about their favorite books, shows, and movies. They would talk about the characters and how they interact. Eventually, they began to ask how certain characters would behave in certain situations, and fan fiction was born.
People started writing their own versions of their favorite literature. There were stories about "Harry Potter," "Buffy the Vampire Slayer," "Lord of the Rings," and countless others. They could be serious or silly, in depth or just short ideas called "headcanons." People were just writing and sharing their ideas, their work, and their imaginations/talents.
However, many writers and networks did not take too kindly to this, and would force the fanfiction writers to take down their work. They would threaten legal action and in some cases sued young writers for all they were worth.
This all changed with J.K. Rowling and Harry Potter fanfiction. The Grand Duchess of writing simply adored that her fans loved her stories so much that they would write their own versions of it. She believed that so long as it was simply for fun, no monetary gain, it was an amazing thing. This lead to the birth of "A Very Potter Musical" and Starkid Productions, one of the most famous and successful amateur theater groups of our time. People began rewriting the stories but if Harry was in Slytherin, or if only his father survived. They hypothesized what the adventures of James Potter and his friends would do for fun, what Harry's kids are like, or what Voldemort's years in school were like. They expanded the Harry Potter world, and they explored aspects that Rowling could never have fathomed, or had time to work on.
Fanfiction gave many writers an outlet to practice creative writing without having to worry about publishing or their work being stolen. It created a place where people could write, critique, and grow as authors. It created a generation of people who ask "what if.." to what they see. People no longer fully accept what they are given at face value. If people love what they see, they'll fully explore every possible avenue. They want If they don't like something, they start asking themselves what would make it better and then they aim to fix it.
Writing has always been a pivotal part of human intelligence, and, statistically, eras when levels of writing were higher led to golden ages of intelligence. The invention of the printing press led to more people being able to read and thus, the Renaissance. More people being able to read led eventually to the Enlightenment Period, when seemingly everyone was writing about politics, society, economics, and revolution. The advent of the typewriter led to a quicker, more streamlined process for writing the great works of the Gilded Age into the Jazz Age. And now, the Internet has made sharing our ideas and our own opinions and imaginations instantaneous.
The power of the human imagination is limitless. Fanfiction may seem like it is just copycatting with a twist, yet it is more like writing based off a prompt. It takes the characters and their known character traits and puts them in situations they would never have been in. It could be as wild as forcing Jon Snow and Tyrion Lannister of "Game of Thrones" to raise a child together. This type of imagination, the constant asking of "what if," is what leads to great works of art, to great innovations, and to great political movements.
So asking "what if 'Buffy the Vampire Slayer' took place in Feudal Japan" may not have the same weight as asking "What if white people and black people could eat in the same restaurant," but it gets writers in the habit of asking questions. Fanfiction puts people in the mindset of looking past what they are given. They don't end a book and let that be the end of that world for them, they create new aspects of it. They won't let a politician tell them how things are and let that be the end of it, they'll look at the world and ask how it could improve and they'll make it so.