One possibility is that Voldemort wants to break Harry's spirit. By putting him in timeout, he isolates Harry from his friends and allies. Harry, being the strong - willed character he is, could use this time to gain some inner strength or discover a new magical ability that will help him when he finally faces Voldemort again.
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.
Hermione could be a main character. She might be trying to find a way to rescue Harry from the timeout situation. Ron could also be there, supporting Hermione in her efforts.
It's hard to say for sure. Given the rather unusual concept, it might be difficult to find one with a widely appealing plot. But in the vast world of fanfiction, there could be some hidden gems. Maybe a plot where Harry, through some magical accident, starts to see things from Voldemort's perspective and tries to'spread' his new - found understanding among others in the wizarding world.
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.
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.
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.
Perhaps a major plot twist could be that Voldemort actually has a change of heart after 'adapting' Harry. He sees something in Harry that makes him question his own evil ways. This could lead to a strange alliance between the two where they try to find a new way to rule the wizarding world that is less about destruction and more about a new form of magic governance. It would be a very unexpected turn considering Voldemort's character in the original series.
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.
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.
Another plot point is that sometimes the circumstances around the prophecy are changed. Maybe Harry figures out a different way to fulfill it that doesn't involve the long, drawn - out battle in the original series. So he's able to use this new understanding to quickly take down Voldemort.