You can try Archive of Our Own (AO3). It has a large collection of fanfictions, and there are bound to be some great ones about young Gellert Grindelwald. Fanfiction.net is also a good place to look. There are many writers who contribute to different fandoms there, and you might find some interesting stories about him.
One good young Gellert Grindelwald fanfiction could be 'The Early Days of Grindelwald'. It delves into his time at Durmstrang and how his ideas started to form. Another might be 'Grindelwald's Youthful Alliances' which focuses on the friendships and rivalries he had as a young wizard. And there's also 'Young Grindelwald: The Road to Darkness' that traces his journey towards the dark path from his early days.
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.
At first, it might be a relationship based on Grindelwald's self - serving motives. He sees Harry as a tool. But as they spend time together, there could be moments of mutual understanding. Harry might start to see Grindelwald not just as a villain but as someone with complex ideas.
Aberforth Dumbledore can be a very important character in these fanfictions. He is Albus Dumbledore's brother and has his own feelings and history related to his brother and Grindelwald. He might be the one who tries to bring his brother back from the brink when Dumbledore is too involved with Grindelwald. Also, Leta Lestrange could be popular. Her family's dark reputation and her own complex relationship with Newt and the wizarding world in general can add an extra layer of drama to the fanfictions involving Dumbledore and Grindelwald.
One great 'Harry Grindelwald Fanfic' is 'The Rise of Grindelwald's Heir'. It has an interesting plot that explores what could have happened if Grindelwald had a secret heir. The character development is well - done, and it keeps you on the edge of your seat.
Well, Grindelwald's back story is quite complex. He was born with great magical talent. In his youth, he and Dumbledore were close, sharing ideas about a new world order for wizards. However, his view became more and more extreme. He believed that wizards should rule over Muggles forcefully. He started a series of dark deeds, using his powerful magic to intimidate those who opposed him. His actions eventually made him one of the most feared dark wizards in history before Voldemort.
In some fanfictions, it might be possible for Harry Potter to be depicted as the heir of Grindelwald. Fanfiction allows for a lot of creative interpretations. However, this goes against the original canon where there is no such indication.
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.