It could be about Harry, Ron and Hermione's careers. Maybe Harry is now a high - ranking Auror, leading teams to fight the remaining dark wizards. Ron could be running Weasley's Wizard Wheezes successfully, and Hermione might be making great changes in the Ministry of Magic with her intelligence.
The main characters are often the children of the original Harry Potter characters. For example, Albus Severus Potter, James Potter, and Lily Potter. Also, Scorpius Malfoy is usually a central character as he is part of the new generation at Hogwarts.
One interesting story could be about the next generation of Hogwarts students facing a new dark threat that the original characters have to help them with. It might involve new spells and magical creatures.
In '19 years later' in Harry Potter fanfiction, we might see the next generation of wizards at Hogwarts. Harry's kids could be getting into all sorts of adventures, just like he did. Maybe they'd be facing new threats to the wizarding world.
The children of Harry, Ron, and Hermione would likely be main characters. For instance, Harry's son could inherit his father's courage and be at the center of a new mystery. He might have to deal with the high expectations placed on him because of his father's legacy.
One possible storyline could be the children of the original characters starting their own adventures at Hogwarts. They might face new threats that are related to the past but in a different way. For example, a new dark wizard could be trying to revive the ideas of Voldemort and the kids have to stop it using the knowledge passed down from their parents.
In some fanfictions, Harry might become a very influential Auror, traveling around the wizarding world to fight dark magic remnants. He could also be involved in reforming the Ministry of Magic, ensuring fairness and equality for all magical beings.
In other fanfictions, new relationships might form. For example, Harry could develop a deep friendship with some of the children of his former enemies. This shows how the wizarding world is trying to heal and move forward. Also, his relationship with Hermione and Ron might evolve in different ways, such as going on new adventures together as a trio even in their later years.
Hermione Granger would be a likely main character. She has always been a central figure. Maybe she's working on some revolutionary magical research or is involved in political reforms in the wizarding world. Her relationship with Ron and their family life could also be part of the story.
Newly discovered magical families could rise to prominence. These families might have been in hiding or just not known before, but now they play a crucial role in the wizarding world of 1000 years later. Their members could be the main characters, bringing in fresh perspectives and magical abilities that were previously unheard of.