If Harry Potter goes to Beacon Hills, he'd probably be quite confused at first. The rules of the supernatural world there are different from the wizarding world. But then, he would start to adapt. Maybe he'd team up with Scott McCall. Harry's experience in fighting Voldemort would give him the courage and skills to face the threats in Beacon Hills, like the Dread Doctors or the Nogitsune.
He could meet Scott McCall. Scott, being a werewolf, would be intrigued by Harry's magic. They could become friends and learn from each other. Harry could help Scott better control his werewolf side using magic, and Scott could show Harry how to survive in Beacon Hills' supernatural chaos.
Well, perhaps Harry could bring his magic to Beacon Hills. He might use his spells to help the locals deal with the supernatural threats they face there. For example, he could use a Patronus to fend off some of the dark creatures that lurk in the town at night.
The Nogitsune could also be a great antagonist. It thrives on chaos and mischief. Percy's presence and his powers would be something the Nogitsune would want to either corrupt or use for its own evil purposes. It could try to possess Percy or those around him to gain access to his demigod abilities.
Well, he might get involved in the supernatural chaos of Beacon Hills. Maybe he'd team up with the local werewolves or other supernatural beings to fight against a common enemy. He could use his demigod powers in unique ways, like using his water control against a fire - based threat in Beacon Hills.
Well, maybe she'd use her magic skills to solve the supernatural mysteries in Beacon Hills. For example, she could help the pack with her spells when they face a really tough enemy that normal means can't defeat.
One idea could be Percy arriving in Beacon Hills and being mistaken for a new supernatural threat. The local pack tries to figure out his powers and intentions. Another could be Percy teaming up with the pack to fight a common enemy that is drawn to the unique energy of Beacon Hills and Percy's own demigod powers. Maybe he also has to adjust to the high school life there while hiding his true identity from most of the students.
The nogitsune could also be a major antagonist. It thrives on chaos and mischief, and a powerful wizard like fem Harry Potter in its territory would surely draw its attention. It might try to possess her or use her magic for its own evil purposes.
The characters in Beacon Hills would be shocked at first. Scott might be a bit wary but also curious. He would want to know more about Harry's magic. Stiles, on the other hand, would be full of questions and would probably pester Harry to learn all about the wizarding world.
One possibility is that Harry's arrival in Beacon Hills shakes up the existing power dynamics. If there are different factions in Beacon Hills, like werewolves, hunters, etc., Harry could be an unexpected wildcard. He might form alliances with some while being a target for others. His magical abilities could either be a great asset or a cause for fear among the residents. For example, if there's a conflict between the werewolves and some dark force, Harry could use his magic to help the werewolves in ways they never expected, but this might also draw the attention of those who don't trust magic in the town.