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.
In some fanfics, the relationship develops gradually. Grindelwald begins by teaching Harry about magic in his own way. Harry is initially resistant but then becomes intrigued. As they face various challenges together, a bond forms. It could be a love - hate relationship where Harry hates what Grindelwald stands for but loves the care he shows in a strange way.
Harry might become more conflicted. He'd be exposed to Grindelwald's ideas which could make him question the black - and - white view of good and evil he had before. His confidence could waver as he's no longer in the familiar Hogwarts environment.
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.
In some fanfictions, the relationship between Harry Potter and Grindelwald can be quite complex. Sometimes, authors might explore a scenario where Harry has to confront Grindelwald's ideology in a new way, different from what we see in the original series. It could be a way to show Harry's growth and his ability to face different forms of dark magic.
Grindelwald's character might also develop in fanfiction by having a redemption arc. He could be influenced by Harry Potter's ideals of love and friendship. For instance, after a series of battles and discussions with Harry, he starts to question his own beliefs and gradually moves towards the light side.
Harry could also develop a more self - reliant and perhaps a bit of a loner personality. Since Grindelwald is not as nurturing as some other potential guardians, Harry would have to fend for himself more often. This would make him stronger in some ways but also more aloof from others, as he would be used to relying on his own skills and judgment rather than on a community or friends.
Often, fanfiction depicts their interaction as intense. Harry, being the hero, is usually in opposition to Grindelwald's dark plans. For example, he might try to stop Grindelwald from gathering more followers or retrieving some powerful dark artifact.
At first, their relationship might be one of student - teacher, with Harry being curious and Grindelwald being manipulative. Harry would be eager to learn from Grindelwald's vast knowledge, but gradually he would start to sense that something is not right.
In a 'Grindelwald Adopts Harry' fanfic, Grindelwald could be seeking to create an heir of sorts. He adopts Harry when he is very young. Grindelwald might expose Harry to a world of magic that is different from what he would have known at Hogwarts. Harry could be taught magic that is more about power and control. However, as Harry gets older, he might discover the truth about Grindelwald's dark deeds and his plans for the wizarding world. This could lead to a great internal struggle within Harry as he has to choose between the man who raised him and what he believes is right for the wizarding community as a whole. There could be a lot of drama as Harry tries to find his place and figure out his true identity in this new and rather dark scenario.
A common plot might involve Grindelwald taking Harry away from the Dursleys much earlier than in the original story. He could introduce Harry to a different side of the wizarding world, filled with ancient and dangerous magic. Harry would then have to decide whether to embrace Grindelwald's vision or fight against it, all while dealing with his own identity and the power he possesses.
His character would likely become more conflicted. Harry was always a symbol of good in the original series, but under Grindelwald's influence, he'd be exposed to different ideas of power and control. He might start to question his own beliefs.