Well, in this fanfiction, a plot twist could be that Harry has some sort of magic that is only activated by his new family connection to Arthur. This magic could be something that is both a blessing and a curse. It could attract unwanted attention from dark forces. Another plot twist could be that the Weasley family has a hidden past related to Harry's parents that comes to light because of this new family relationship. This could change how Harry views his parents' death and his own role in the wizarding world. And maybe there is a character within the Weasley family who is not what they seem, and Harry's new position as Arthur's brother makes him the only one who can uncover the truth.
One plot twist could be that Voldemort tries to use Harry's new family ties to get to Arthur and the Ministry. Another could be that Harry discovers some long - hidden family secret that changes his view of the Weasley family and his place in it.
One plot twist could be that Harry's real father was not James Potter but an unknown figure from Hawkgirl's world. This would completely change the dynamics of his family story. Another could be that Voldemort discovers Harry's Hawkgirl heritage and tries to use it against him by creating a spell that combines dark magic with the technology or powers associated with Hawkgirl's world.
Well, it could be that Harry, as James' brother, discovers that there were more secrets about his first life than he thought. Maybe he finds out that there was a hidden power within him that was never fully awakened in his previous life. This new discovery could change the way he approaches magic and his role in the fight against the Dark Arts, and it might also lead to a different ending to the battle against Voldemort.
One possible plot twist could be that Harry, as James' brother, has a different role in the fight against Voldemort. Maybe he's more of a behind - the - scenes strategist. Since he's in the family earlier, he could have different relationships with the other characters too. For example, his bond with Sirius might be even stronger as they grow up together more closely.
A plot twist might be that Harry's past enemies from the wizarding world somehow find a way to cross over into the Naruto world. This would force Shikaku and Harry to team up not only with the ninjas but also with some of Harry's old friends from Hogwarts. It would create a really chaotic and interesting situation where two different worlds' powers and skills collide.
A potential plot twist could be that Harry actually has a hidden agenda. He accepts Voldemort's offer just to get closer and find a way to defeat him from the inside. He might pretend to be on Voldemort's side while secretly working against him.
There could be a lot of conflict too. Bruce is used to working alone in the shadows, while Harry is used to having friends and allies at Hogwarts. Harry might want to use magic more openly to solve problems, which could clash with Bruce's more stealthy and non - magical approach in Gotham. Also, they may have different views on how to deal with enemies, with Harry perhaps more inclined to rehabilitate and Bruce more focused on incarceration.
Well, one possible plot twist could be a revelation about a character's true heritage that was hidden all along. For example, a minor character might turn out to be related to one of the major wizarding families in ways no one expected.
A really interesting plot twist in some fanfictions is that the Hogwarts houses are not what they seem. For example, Gryffindor was originally founded to be a sort of 'cover - up' for a secret society within Hogwarts that had a much darker purpose. Or that Slytherin was actually trying to protect the wizarding world from an even greater evil, but his methods were misinterpreted. This changes the whole dynamic of the story and how we view the different houses.
The protective brother can change the plot significantly. For instance, if he's highly skilled in magic, he can prevent Harry from getting into some of the dangerous situations he faces in the original series. He might be able to stop Harry from entering the Triwizard Tournament by interfering with the Goblet of Fire's magic. This would then change the entire course of that year at Hogwarts and Harry's relationship with Cedric Diggory and others.
One possible plot could be that Harry discovers his true heritage as King Arthur's son. This would likely throw the wizarding world into chaos as it challenges the existing ideas about his family. He might inherit some of Arthur's leadership and combat skills, which could be used to fight Voldemort in a new and unexpected way.