Well, Hagrid would be overjoyed. He loves Harry so much, and having a twin sister would mean more family for Harry in his eyes. He might even try to give Bella a tour of the Forbidden Forest, much to the dismay of others. In the Twilight world, the werewolves would be on edge. They already don't trust the Cullens, and now with Harry in the picture, they'd be worried about what new threats or changes could come. The Dursleys would be horrified if they ever found out. They barely tolerated Harry, and the thought of another 'freak' in the family would be too much for them. And the students at Hogwarts would be gossiping non - stop, speculating about how two such different people could be twins.
In Hogwarts, the teachers would have mixed reactions. Dumbledore would be intrigued and see it as another part of the grand plan. Snape would probably be his usual sour self, but also secretly curious. Hermione would be eager to learn about Bella's world and would probably start researching right away. In Forks, Bella's human friends like Angela and Jessica would be shocked. They already thought Bella was a bit odd, and now this? Charlie, Bella's father, would be very protective and would want to make sure Harry was a good influence on his daughter. The Volturi, on the other hand, would see it as a potential threat or an opportunity to gain more power if they could somehow use this connection between Harry and Bella.
The Weasleys would probably be very welcoming to Bella. Molly would likely try to mother her just like she does with Harry. Ron might be a bit jealous at first, thinking Bella would steal some of Harry's attention. In the Twilight world, the Cullens would be cautious. Carlisle, being the rational one, would want to study this new connection between Bella and Harry. Edward might be a bit possessive over Bella still, but also curious about her new 'twin' and his world. Jacob would be confused and probably a bit angry, seeing yet another strange element in Bella's life.
If they were twins in fanfiction, they'd likely have a very unique bond. Harry is used to being the 'chosen one' in his world, but with Bella as his twin, she might also share some of that destiny. They could have a connection that allows them to sense each other's danger. For example, when Harry is in trouble at Hogwarts, Bella might feel a strange unease all the way in Forks. And when Bella is facing the Volturi, Harry could have some sort of premonition. Their powers could also combine in unexpected ways. Maybe Harry's ability to use spells could be enhanced by Bella's strong willpower.
Harry would likely be cautious at first. He's used to dealing with his own set of magical beings, and Bella is something new. Bella, on the other hand, would be curious and a bit overwhelmed by the wizarding world. They might start by simply asking each other questions. Harry would want to know about Bella's world, like how vampires function there, and Bella would be eager to learn about magic spells. As they get to know each other better, they could become friends and rely on each other's strengths in difficult situations.
In Percy Jackson, the gods themselves would have mixed reactions. Zeus might see the twins as a threat to the balance of power between the worlds. Poseidon and Athena, on the other hand, might be more intrigued and want to use the twins to their advantage. In the Harry Potter world, the students at Hogwarts would be divided. Some, like Ron, might be a bit wary, while others, like Luna, would be very open - minded. The Death Eaters would likely see the twins as something to be exploited if they thought it could help their dark cause.
For the Harry Potter characters, Ron would probably be a bit jealous of the twins' cool powers at first. But as he gets to know them, he would become friends. Snape would be highly suspicious and might even try to find a way to control them. In the Percy Jackson realm, the other demigods would have mixed reactions. Some would be in awe of their magic, while others would be worried that they might bring too much attention from the wizarding world. The twins would have to work hard to gain the trust of both sets of characters.
Hermione, on the other hand, would likely have a more critical view. She'd analyze the fanfictions for their accuracy in terms of magic lore and Hogwarts traditions. If there were any inaccuracies, she'd be quite perturbed. However, she might also appreciate the creativity that goes into some of the well - written ones that add new dimensions to their magical world.
Hermione would probably be very curious. She would start asking the gods all sorts of questions about their magic and their history. Ron, on the other hand, might be a bit intimidated at first but would soon warm up when he realizes they can offer some help against the Dark forces.
At first, it might be a bit rocky. Harry would be confused about this new place and Bella, and Bella would be a bit overwhelmed by the sudden presence of a magical child. But as time goes on, they would start to bond. Bella would see Harry's vulnerability and his need for love and protection, and Harry would see Bella as a source of stability in this strange new world.
Some characters might be amused. For example, Ron would probably find the wilder and more comical fanfictions really funny. He'd be laughing out loud at the absurd scenarios where he's made into a heroic food - loving wizard who saves the day with a well - timed puking pastille.
Edward might be extremely protective. He already has a strong urge to keep Bella safe, but with the added connection to the Joker, he'd be on high alert. He might be worried about the Joker's influence on Bella and try to keep her away from that part of her life.
Edward might be very protective of the twins. Since he has a close relationship with Bella, he would see it as his duty to keep the twins safe from any harm. He could also be interested in seeing if the twins have any special abilities related to his own mind - reading ability.