One interesting plotline could be Harry somehow traveling back in time to meet Grindelwald in his prime. This could lead to a battle of wits between them, with Harry trying to stop Grindelwald from starting some of his more heinous plans early. Another might be that Grindelwald, seeing Harry's power, tries to recruit him to his side, offering him power and knowledge that Harry has to resist.
In some fanfictions, there could be a plotline where Harry Potter discovers a hidden connection between himself and Grindelwald. Maybe through some ancient magic or a family secret. This connection then leads to a series of events where they must interact and understand each other better. For example, they might have to exchange magical knowledge to solve a mystery that is plaguing the wizarding community. Or perhaps Harry has to enter Grindelwald's mind to find a way to defeat a common enemy, which is a very mind - bending and exciting plot.
One possible plotline could be Harry's internal struggle with his heritage. Since Grindelwald was a dark wizard, Harry might battle with the idea of having such a connection. He could face prejudice from the wizarding world while also trying to understand if there are any redeeming qualities in Grindelwald's ideology that might be passed on to him.
Plots that involve Grindelwald's unorthodox magical experiments are really captivating. In 'Grindelwald's Forbidden Magic', the fanfic shows how his experiments could have changed the wizarding world if they had been fully realized. It's full of mystery and danger.
One interesting plotline could be exploring their early days at Hogwarts together. Maybe they were both brilliant students with different outlooks that gradually diverged. Another could be a story where they meet again after Dumbledore defeats Grindelwald, and there are still unresolved feelings and thoughts between them. A third one might be a fanfiction that delves into an alternate universe where they actually work together to achieve some 'greater good' that they both misinterpreted in different ways.
One possible plotline could be that they meet in the library while searching for a rare book. Harry might be looking for something to help him with a difficult class assignment, and Daphne could be researching dark magic for a different reason. They start off as rivals in this search but gradually develop a mutual respect and then friendship that could potentially turn into something more.
One possible plotline could be that Harry, perhaps lost in the forest near Forks, stumbles upon Carlisle. Carlisle, being the kind-hearted vampire he is, offers to help Harry. They start to exchange stories about their different worlds, with Harry sharing about the wizarding world and Carlisle about the vampire society. This could lead to an unlikely friendship where they work together to protect both the wizarding and vampire communities from common threats.
Dumbledore would be a great addition. Since he has a long history with Grindelwald, his presence could add a lot of depth and backstory to the fanfiction. Another good character could be Hermione. Her intelligence and knowledge of magic could help Harry in his encounters with Grindelwald. Also, Newt Scamander could be included. Given his experience with magical creatures and his own adventures in the wizarding world, he might be able to offer unique perspectives and assistance.
Maybe Harry finds himself in a situation where he has to team up with the Marauders to fight a common enemy that was previously unknown in the original Potter story. This would create a whole new dynamic and show how different generations of Hogwarts students can work together.
One plotline could be Harry's discovery of his relation to Grindelwald. Maybe he finds an old family heirloom or a hidden letter that reveals the truth. Another could be how the wizarding community reacts to this news. Some might fear Harry, thinking he has inherited Grindelwald's dark tendencies.
One possible plotline could be Harry initially being forced into the training but then gradually getting intrigued by Grindelwald's knowledge. He might start to question the traditional teachings of Hogwarts. Another could be that Harry is tricked into the training, thinking Grindelwald has good intentions only to discover the truth later.