There are many potential characters. The teachers at Forks High School for sure. Harry could have interesting conversations with them. Also, if there are any other supernatural beings in the Forks universe in this fanfiction, like werewolves, he could interact with them. And of course, the students who are into different clubs and activities at the school. He might bond with the science - loving students or those on the school newspaper team, sharing his own experiences from Hogwarts in a veiled way.
Well, if we think about it, Harry could interact with the Forks High School principal. This interaction could be quite comical as the principal tries to figure out this strange new student. He might also cross paths with some of the more popular students at the school who could initially be a bit standoffish but later become friends. And if there are any local witches or warlocks in this fanfiction (even though Forks is known for vampires and werewolves), he could have some really deep conversations with them about the differences between their magic and his.
Obviously, Buffy would be a major character he'd interact with. They could start off as wary of each other but then grow to respect one another's fighting skills. Giles too, as he has a wealth of knowledge about the supernatural, and he and Harry could have some interesting discussions about different types of magic.
Well, perhaps Harry would struggle to fit in at first. He might be shocked by the normalcy of Forks High School compared to Hogwarts. Maybe he'd make new friends and introduce them to some of his magical knowledge in a very discreet way.
He could meet Bella. Since Forks is Bella's hometown in the 'Twilight' series. They might become friends or have some kind of adventure together.
Well, he'd probably be really confused at first. I mean, Hogwarts is all about magic and Forks High School is a normal Muggle school. He might accidentally use magic when he's frustrated with a difficult class like Potions... I mean, Chemistry. And he'd surely stand out with his lightning - shaped scar.
One character could be Dobby. Even though Harry is living alone, Dobby might still find a way to visit him and offer his help. Another could be the Hogwarts ghosts. They can pass through walls and might visit Harry in his solitary abode.
Obviously, Hagrid could be one. He would be so amazed and probably take baby Harry on little adventures around the Hogwarts grounds, listening intently to what Harry has to say.
A potential character could be a reclusive old wizard who lives on the outskirts of the wizarding world. This wizard might have his own reasons for living in seclusion, but when he sees Harry's loneliness, he takes him under his wing. Another character could be a young, orphaned witch who is also trying to find her place in the post - war wizarding world and she crosses paths with Harry.
Definitely the Cullens. Since they are the main vampire family in Forks, they could be great allies. They have their own set of powers and knowledge of the area. Harry could also befriend Bella, who has her own connection to the supernatural world in Forks.
Sakura might be one of the characters. She has her own set of skills in the medical and combat fields. Meeting Harry could lead to exchanges of knowledge about different forms of healing and combat magic.
He could meet the main characters from Death City. For example, Maka Albarn and Soul Eater Evans. They could be initially cautious around Harry but then become friends as they realize his good intentions.