In this fanfiction, it could start with a chance encounter. Harry could be lost in a magical forest near Bill's place. Bill finds him and takes him home. There, Harry gets to know Bill's family better. They form a bond over their shared love for magic and stories of the wizarding world. As they grow up, they continue to support each other through different challenges at Hogwarts and in the wizarding community at large.
Well, perhaps they could become friends quickly. Bill might introduce Harry to some interesting magical things he hasn't seen before, like some unique creatures. And they could start having little adventures together around the wizarding world.
They might start as a sort of mentor - mentee relationship. Bill, being more experienced, can guide Harry in the wizarding world. As time passes, they could become like brothers, always having each other's backs.
In a 'Percy meets Triton at a young age' fanfiction, it could start with Percy being bullied at the beach. He runs into the water to get away from the bullies. Triton, who is observing from afar, is intrigued by Percy's quick thinking to use the water as an escape. Triton approaches Percy and offers to give him the ability to breathe underwater for a short time. They then have a conversation where Triton tells Percy about his own powers and how the ocean can be both a friend and a foe. This encounter plants the seed for Percy's future adventures in the underwater world.
Well, perhaps they could go on an adventure together. Maybe they discover a hidden magical place in the Forbidden Forest. They might use their combined skills, Harry's courage, Bill's experience with magical creatures, and Charlie's knowledge of dragons to overcome some sort of danger or mystery.
One possible plot could be that Hermione meets Bill and Charlie during a magical creature research project. Bill's extensive knowledge of magical creatures from his work with Gringotts and Charlie's expertise from his time at the dragon reserve in Romania could complement Hermione's academic approach. They might start off a bit skeptical of each other, but as they work together, they come to respect and rely on one another, with Hermione learning a great deal from their practical experiences.
In this fanfiction, perhaps Harry will be initially hesitant and quiet when meeting Bill and Charlie. He might be in awe of their more experienced and confident personas. Bill could offer Harry some words of wisdom regarding the wizarding world outside of Hogwarts. Charlie, on the other hand, might share stories about dragons which would both fascinate and intimidate Harry.
One possible plot could be that Bill mentors Harry in the art of ancient magic. Since Bill has been around for a while and has dabbled in many different areas of magic, he could introduce Harry to spells and magical knowledge that has been long forgotten. This could help Harry in his future battles or in his general understanding of the magic world.
Well, it could be about Harry Potter, in his younger days, stumbling upon a teen Teddy. Maybe they team up to face some sort of magical mystery in Hogwarts. For example, they might find a strange enchanted object that's causing chaos in the school and they have to figure out how to stop it.
In the 'bill cipher meets black hat fanfiction', it could start with Bill Cipher getting bored in his own dimension and decides to explore other realms. He stumbles upon Black Hat's domain. At first, Black Hat is hostile towards this strange triangular entity. But Bill Cipher, being his glib self, tries to convince Black Hat that they could achieve greater things together. Black Hat, seeing the potential of Bill's powers, reluctantly agrees. Then they embark on a journey of causing chaos across different universes, with each having their own motives hidden beneath their new - found partnership. Their interactions would be filled with mistrust and power plays as they constantly try to one - up each other while still maintaining their joint goals of destruction and domination.
One possible plot development could be that Harry develops a fear of dogs. This fear might then become a character trait that affects his actions in other situations. For example, he might be hesitant to enter certain areas where he suspects dogs could be present. Another development could be that the attack was not accidental. Maybe there's a dark wizard using the dog as a tool to harm Harry, and this discovery could lead to a whole mystery-solving adventure for Harry and his friends.
One possible plot could be that Harry, through some time - traveling magic, meets young Severus. Harry, knowing Severus' future, tries to befriend him and change his path. He could introduce Severus to different ways of using magic that are less dark - oriented, which might change Severus' perception of magic and his future relationships in Hogwarts.