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.
Well, perhaps a plotline where Harry is trained by Grindelwald in secret while still attending Hogwarts. He has to keep his training a secret from his friends and teachers. As he progresses in his training, he starts to have a different perspective on the war against Voldemort, as Grindelwald might have his own views on that matter. This could lead to a lot of internal conflict for Harry as he tries to balance what he's learning from Grindelwald and his loyalty to his friends and the wizarding world he knows.
Well, perhaps in this fanfiction, Grindelwald trains Harry to be a sort of double agent. Harry would learn Grindelwald's ways so that he can infiltrate the dark wizard's followers. Grindelwald thinks he can control Harry, but Harry is secretly using the knowledge to gather information for Dumbledore. Along the way, Harry would face a moral dilemma as he has to pretend to embrace the dark arts while still holding onto his own values.
Well, it depends on what you consider 'good'. Some people might like the ones that focus on Harry's internal struggle while being trained by Grindelwald. For example, there could be fanfictions where Harry has to decide whether to follow Grindelwald's teachings or stick to his own values. However, not all such fanfictions are well - written. Some might have plot holes or out - of - character moments.
Perhaps Grindelwald teaches Harry about the history of magic in a very different way than what Harry has learned before. He might show Harry the secrets of magic that have been hidden by the wizarding world's authorities. This could lead Harry to question the existing order and his own beliefs. Maybe Harry starts to see the gray areas in the battle between good and evil.
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.
Perhaps in the fanfiction, Harry is trained by Grindelwald to face a greater, unknown threat. Grindelwald could be using Harry as a tool to achieve his own ends, but in the process, Harry discovers hidden aspects of the wizarding world. This could include ancient spells or secrets about the origin of magic that Hogwarts has long forgotten or suppressed.
A plotline might involve the magical community's reaction. Since Grindelwald was a feared dark wizard, when the news spreads that Harry is his grandson, there could be a lot of chaos. Some might fear that Harry has inherited Grindelwald's dark tendencies. However, Harry could use this situation to prove that one's upbringing and choices matter more than blood relation. He could embark on a journey to clear the name of the Potter family and show that he is different from his grandfather.
Harry might start off as a bit naive about the darker aspects of magic. But as he is trained by Grindelwald, he becomes more aware of the grey areas in the wizarding world. His character could become more conflicted as he is exposed to Grindelwald's teachings. He may question his previous beliefs and values.
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.
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.
In the 'harry trained by grindelwald fanfic', the character development of Harry would be a key point. Harry, who is used to the values of Dumbledore and Hogwarts, now has to adapt to Grindelwald's teachings. This could lead to an internal struggle within Harry. He might question his own sense of right and wrong. Also, the plot could involve Harry using the skills he learned from Grindelwald to face new threats or solve old mysteries in a completely different way than what we expect from the original series. The fic could also introduce new magical elements or interpretations of existing magic based on Grindelwald's knowledge.