Well, it could involve Voldemort having some strange newfound attraction to Harry and trying to make Harry his 'queen' in a very dark and twisted way. Maybe he uses dark magic to bind Harry to him and Harry has to find a way to break free.
The plot might start with Voldemort realizing that Harry has some sort of power or essence that he desires. So he decides to make Harry his queen. Harry, of course, resists this. Along the way, there could be battles between the Order of the Phoenix and Voldemort's forces, with Harry in the middle, trying to figure out how to use his situation to defeat Voldemort once and for all. There could also be some sort of internal struggle within Harry as he has to deal with the strange feelings that Voldemort's actions might evoke in him.
There could be. The Harry Potter fandom is huge and diverse, with fans exploring all kinds of creative and sometimes out - of - the - box ideas. So it's not unlikely that someone has written a fanfic with this concept. But it may be a bit of a niche idea within the fandom.
One possible plot could be that Harry tries to reason with Voldemort about the futility of his dark ways. He might talk about how much destruction Voldemort has caused and how many lives have been lost. Harry could also try to appeal to any remaining shred of humanity in Voldemort, perhaps by bringing up his own orphan status and how they both lost their parents in a way, though for very different reasons.
Maybe Harry has all of Voldemort's powers but uses them for good. He could start to look like Voldemort but with a kind heart, and he uses his new - found dark magic to fight off new threats that are even more powerful than Voldemort ever was.
In the 'harry joins voldemort fanfic', it could start with Harry being captured by Voldemort. Instead of killing him immediately, Voldemort decides to brainwash him. Through a series of dark magic spells and psychological manipulation, Harry starts to see Voldemort as a mentor. As time passes, Harry becomes an integral part of Voldemort's inner circle, helping him plan attacks against the wizarding world, believing that they are actually for a greater good as Voldemort has convinced him.
Well, one possibility could be that Voldemort adopts Harry as a way to control the wizarding world. He might think that by having Harry on his side, the resistance against him will crumble. Another could be that Voldemort discovers some sort of connection between him and Harry that makes him want to take Harry under his wing, perhaps related to some long - forgotten prophecy.
In such a fanfic, the plot could involve Harry finding a long - lost magical artifact that reveals his connection to Voldemort as his heir. As a result, he starts to have strange dreams and visions similar to what Voldemort had. The wizarding world would be in chaos as they try to figure out if Harry is going to turn to the dark side. Harry himself would be in a moral dilemma, trying to decide whether to embrace this new identity or fight against it.
In this fanfic, perhaps Voldemort has some grand plan. He puts Harry in timeout to wait for the right moment. He might be using this time to gather his Death Eaters and prepare for a big showdown. Harry, while in timeout, could be thinking of ways to break free and defeat Voldemort once and for all.
One possible plot could be that Harry, initially shocked and confused, discovers his true parentage. Voldemort, instead of seeing Harry as an enemy, tries to groom him to be his heir. Harry might struggle with his new identity, having grown up believing he was an orphan with no relation to the Dark Lord. He could be torn between the values he learned at Hogwarts and the dark allure of his father's power. Eventually, he might use his unique position to try and change Voldemort's ways, or he could completely reject his father and fight against him in a new way, using his knowledge of Voldemort's weaknesses from their family connection.
Well, one possible plot could be that Harry is somehow transformed into the snake against his will. He then has to figure out how to break the spell while being in the form of the snake and also being close to Voldemort. He might use his knowledge of Voldemort's secrets to his advantage even in that form.
One possible plot could be that Harry discovers a prophecy that in order to truly end the dark magic in the wizarding world, he has to get close to Voldemort by becoming his assassin. So he pretends to be on Voldemort's side, all the while planning his demise.