A really interesting plot twist could be around the Half - Blood Prince himself. The fanfiction could explore the idea that the identity of the Half - Blood Prince was misinterpreted in the original book. Maybe it was a red herring, and there was someone else who was the true 'Half - Blood Prince' all along, with a completely different set of motives and actions that would have a major impact on the story.
For Ron, fanfictions might develop his insecurities further. He could struggle more with the idea of Harry being in the spotlight all the time, especially when it comes to the knowledge from the Half - Blood Prince's book. This can make his character more complex and relatable as he tries to find his own place within the group and Hogwarts.
Perhaps in some fanfictions, the past reveals that there was a secret alliance between the Leaf Village and an enemy village long ago. And in the future part of the fanfic, this alliance resurfaces and creates a whole new dynamic among the characters. It might lead to Naruto having to make difficult choices between loyalty to his own village and this newfound connection.
Well, sometimes in these fanfictions, the reborn Ultron might find out that it was created with a hidden purpose by an even more shadowy figure. This discovery could lead it on a journey to uncover the truth about its origin, and along the way, it has to decide whether to continue its vendetta against the Avengers or not. It's really interesting to see how the writers play with this concept of self - discovery.
One interesting plot twist could be that a minor character from Hogwarts, like Neville, discovers a hidden power within the Deathly Hallows that was previously unknown. Maybe he realizes that the Elder Wand has the ability to not only transfer power through combat but also through acts of self - sacrifice, which completely changes the way everyone views the power of the Hallows.
Many such fanfictions also tend to create new magical elements or spells that are in line with the magical world of Harry Potter. They might introduce new potions or magical artifacts that tie in with the theme of the Half - Blood Prince's expertise in potions. For instance, a fanfic could have a new potion that Snape was secretly working on. Moreover, they usually stay true to the overall tone of the series, which is a mix of mystery, adventure, and a touch of the dark side, especially when dealing with Voldemort's influence and the secrets that are being uncovered throughout the story.
A really cool plot twist in Hermione as a Marauders' daughter fanfictions is when she realizes that her real mother was a powerful witch who was erased from history by some dark force. This makes her quest not only about finding her place as the Marauders' daughter but also about restoring her mother's name. Another plot twist could be that the Marauders had some sort of magical pact that is now passed on to Hermione. This pact might force her to make difficult choices between her loyalty to her new - found family and her friends. And sometimes, there's a plot twist where Hermione discovers that she has a twin sister who was separated from her at birth, and this sister has been living in the shadows, also with a connection to the Marauders, which throws a whole new set of challenges her way.
Another possible plot twist is if the Forerunners from Halo are somehow related to the ancient magic in Familiar of Zero. Maybe they left behind some technology or knowledge that is now perceived as magic in the Familiar of Zero world. This would open up a whole new avenue of exploration for the characters, as they try to understand the true nature of their powers and the connection between the two universes.
Perhaps in some fanfictions, a major villain from 'Worm' teams up with a powerful organization from 'Darker than Black'. This alliance could lead to a whole new set of challenges for the heroes of both universes. They would have to put aside their differences and find a way to combat this unexpected union. This plot twist not only changes the power dynamics but also forces the characters to grow and adapt in new ways.
One interesting plot twist could be that Snape's blood adoption gives Harry some of Snape's memories. This would allow Harry to see Snape's true motives throughout the years, not just the ones Dumbledore had revealed. Another could be that the adoption gives Harry a new magical ability related to Snape's potions expertise, like the ability to brew extremely powerful potions without much effort.
One common plot twist could be that they initially seem to be enemies but are actually long - lost brothers. Another might be that they both get caught in a strange alternate universe where their roles are completely reversed. And a third could be that an outside force tries to make them fight, but they end up teaming up against it.