The plot might involve the OC using their knowledge from their previous life to navigate the wizarding world during Grindelwald's rise. They could end up being a double agent, pretending to support Grindelwald while actually working against his more heinous plans.
The OC's character would likely start with an idealized view of Grindelwald. As the story progresses, they might see the darker side of his actions more clearly. This could lead to a crisis of faith within the OC, causing them to question their own beliefs and values.
Love and loyalty are also common themes. The OC could fall in love with someone in Grindelwald's inner circle or have to choose between loyalty to their friends and family and loyalty to Grindelwald. This creates a lot of internal conflict for the character and drives the story forward in many different ways.
One challenge would be the stigma. The wizarding world would likely view him with suspicion. He might have trouble making friends or being accepted into certain groups.
The plot could also involve the OC being hunted by those who fear he will follow in Grindelwald's path. This would create a lot of action and suspense. He would have to constantly be on the run while also trying to prove that he is not like his father. He could seek refuge with a group of rebel wizards who are fighting against the remnants of Grindelwald's followers.
There's also 'Grindelwald's Hidden Ally'. In this fanfiction, the original character has special powers and forms a complex relationship with Grindelwald. The story is full of mystery and intrigue as the OC tries to navigate the dark wizard's world. It shows how an original character can be integrated into the existing lore quite well.
In such a fanfiction, the OC son of Grindelwald could have unique magical abilities. Since Grindelwald was a very powerful dark wizard, perhaps the son inherits some extremely potent magic. However, he might use it in unexpected ways. Maybe instead of using it for aggression like his father, he uses it to protect the weak. For instance, he could have the power to control the elements, but he uses it to shield a Muggle village from a dark wizard's attack, defying the common perception of Grindelwald's descendants being inherently evil.
First, create a well - developed OC. Give them a unique backstory, personality, and set of magical abilities. For example, an OC who grew up in an orphanage for magical misfits and has a special power to sense dark magic. Then, tie their story into Grindelwald's. Maybe they were influenced by his early speeches. Also, make use of the existing Harry Potter lore. Use familiar locations like Hogwarts or Diagon Alley in new ways in relation to the OC and Grindelwald.
To write a compelling OC in Gellert Grindelwald fanfiction, first, give them a unique backstory. Maybe they come from a long - lost magical family or have a special connection to an ancient magic. Second, define their personality traits clearly. Are they brave but reckless? Or perhaps wise but a bit naive? Third, give them a goal or motivation that ties into the story. For example, if they want to stop Grindelwald, what made them take on this huge task? Also, make sure their appearance is distinct. It doesn't have to be overly elaborate, but something that makes them stand out, like a unique hair color or a special piece of jewelry.
One popular trope is the 'Powerful Alliance' trope. In many Gellert Grindelwald OC fanfictions, the original character (OC) forms an unexpected alliance with Grindelwald. This could be because the OC has a unique power or knowledge that Grindelwald wants to utilize for his own grand plans. Another common trope is the 'Redemption Arc' for Grindelwald through the influence of the OC. The OC might see some good in him deep down and tries to steer him away from his dark path. Also, the 'Mystery Unraveling' trope is often used. The OC gets involved in Grindelwald's world and starts to uncover secrets about his past, his true motives, and the dark magic he's dabbling in.