One possible plotline could be Harry struggling to regain control of his mind while Voldemort tries to use his body to carry out evil deeds. For example, Harry might have to fight against Voldemort's commands internally. Another could be how his friends notice the strange behavior and try to figure out what's wrong and save him.
The struggle for control is a big theme. Voldemort wants to use Harry's body for his own evil plans, but Harry resists. There's also the theme of identity. Harry starts to question who he really is when Voldemort's influence seeps in. And a third theme could be the power of friendship. Sometimes, it's his friends' love and support that helps him in his fight against the possession.
Well, 'Shadows in Harry's Soul' is a fanfic that's quite good in this regard. It starts with a slow build - up of Voldemort's influence over Harry. As the story progresses, we see Harry's attempts to break free from the possession. The fic also has some interesting sub - plots involving the other characters trying to figure out what's going on with Harry and how to save him.
The other Hogwarts students would be a mix of scared and curious. Some might avoid Harry altogether, fearing that they could be in danger. Others, who are more brave or naive, might try to approach him to see if they can help. The teachers would be in a difficult position. They would need to protect the other students but also try to find a solution for Harry. For instance, Professor McGonagall might be torn between her loyalty to Harry and her duty to keep the school safe.
Well, in some of these fanfictions, Harry's magical abilities might change when possessed. He could start using dark magic in ways he never would have before. It makes for a really interesting twist on his character. For example, he might struggle against Voldemort's will while still being forced to do some dark deeds, creating a complex internal battle.
Harry Potter is central as the possessed. Voldemort is crucial as the possessor. Harry's friends are bound to be main characters. Hermione, with her intelligence, would be constantly observing Harry's strange behavior and coming up with theories. Ron, being Harry's loyal friend, would be by his side and ready to fight for him. Also, characters like Sirius Black, if he's still alive in the fanfiction's timeline, could be involved. He has a close connection to Harry and would surely want to help him get rid of Voldemort's control.
Another option is to check out some Harry Potter - focused fan communities on social media platforms like Reddit. There are often threads where fans recommend their favorite fanfictions, and you might come across some 'Harry possessed by Voldemort' ones among them.
In this fanfiction, it could be that Voldemort has a premonition. He sees that if Harry Potter dies, it will lead to a series of disasters that will also destroy his own plans. So, in order to preserve the balance or to keep his long - term goals intact, he saves Harry. For example, if Harry's death causes an uncontrollable chaos in the wizarding world, Voldemort's rule over the dark forces might be disrupted. So he steps in to save Harry.
The wizarding world might be in shock. People who have always seen Voldemort as the ultimate evil would be confused. They would have to re - evaluate their views on Voldemort. Harry, on the other hand, would be in a very strange situation. He might be distrusted by some of his friends who think he has made a deal with Voldemort.
The relationship would become extremely complex. Harry would be confused and conflicted. He's been taught all his life that Voldemort is pure evil, but now he's been saved by him. Voldemort, on the other hand, might start to see Harry in a different light, perhaps as a tool or as someone with whom he can form an unusual bond. It would be a relationship full of mistrust on Harry's part and manipulative intentions on Voldemort's.