The 'direction of change' in a Harry Potter fanfic could refer to many things. It might be the change in a character's personality. For example, if a normally shy character becomes more confident as the story progresses. It could also be about the change in the overall plot, like the wizarding world moving from a state of relative peace to one of chaos due to a new dark force emerging.
Obviously, Harry Potter himself could be a main character. He could interact with the members of One Direction, like Niall Horan. Maybe Niall is a new student at Hogwarts and Harry is assigned to show him around.
One idea could be that the members of One Direction are secretly wizards and they end up at Hogwarts. They could form a new club there, combining their muggle music with magic. For example, they use spells to make their instruments play on their own during a concert at Hogwarts.
The popularity of 'One Direction Harry Potter' fanfics comes from the combination of two huge fan bases. Fans of One Direction are always eager to see their idols in different scenarios, and the magical world of Harry Potter provides a great backdrop for that. It's a chance to see their favorite singers in a world full of magic, spells, and adventure.
Using the plot structure is crucial. If the fanfic's plot is about a mystery, like a new dark magic item that's causing trouble in the wizarding world, the 'direction of change' can be shown as the characters get closer to solving the mystery. They change from being confused to having a clear understanding, and this shift is the 'direction of change'.
First, work on the characterization. Really study the members of One Direction, their mannerisms, speech patterns, and values. This way, you can ensure that they are in - character in your fanfic. For instance, Louis Tomlinson's sense of humor should be accurately reflected if he's a character in your story.
One good example could be a fanfic where Harry is sick during a tour. The story might focus on how the other band members take care of him. They could bring him warm tea and make sure he gets enough rest between shows.
I've read a fanfic titled 'One Direction and the Sorcerer's Stone'. In this story, the members of One Direction accidentally stumble upon the Philosopher's Stone while on a tour in England. They then get caught up in the world of Hogwarts and all the danger that comes with protecting the stone. It's full of action, humor, and a bit of romance too as they interact with the Hogwarts students.
One possible storyline could be that the members of One Direction are secretly wizards attending Hogwarts. They could form a new kind of wizard band within the school, using magic to enhance their music. For example, they might use spells to create amazing light shows during their performances in the Great Hall. Another storyline could be that they are on a mission to help Harry Potter defeat Voldemort in a more modern, musical way. Maybe their music has the power to weaken the dark forces.
Well, perhaps One Direction could be a wizarding band in the Harry Potter universe. They could perform at the Yule Ball, and Harry and his friends could be huge fans. Maybe they'd even help the boys fight off some dark wizards who are after their magical music.