A magical creature could also be an important character. Imagine a friendly house - elf that they meet. The house - elf could be in some sort of trouble, and Harry and Daphne decide to help it. This adventure with the house - elf could shape their relationship and also introduce them to different aspects of the magical world.
Well, they might become friends. Maybe they discover they have a shared interest in magic even before getting to Hogwarts. For example, they could both be fascinated by magical creatures and exchange stories about the ones they've read about.
Hermione could be involved. She might suspect Daphne of having ulterior motives regarding Harry and try to warn him, which could play into the betrayal storyline in some way, either as a catalyst or as someone who helps Harry deal with the betrayal later.
Some fanfictions might include Luna Lovegood. Her unique personality and magical insights could add an interesting dimension to the harem. She could be the one who brings a sense of calm and otherworldly wisdom to the group.
One possible plot could be that they meet in Diagon Alley. Maybe Harry is lost while shopping for his school supplies and Daphne helps him find his way. This could start a friendship where they exchange stories about their expectations for Hogwarts. It might also be a chance for Daphne to see Harry as more than just the famous Boy - Who - Lived, and for Harry to make a friend outside of the Weasleys and Hermione.
Hermione would probably be in it. Since she's Harry's best friend, she might offer her intelligence and advice to Harry and Daphne in their post - war endeavors. Maybe she helps them with research or legal matters if they're trying to change things in the wizarding world.
They could meet MACUSA officials. These are the magical authorities in America and would likely play a role in any story set there.
Maybe they attend a pre - Hogwarts magic class together. Harry struggles a bit with some of the advanced spells being taught, and Daphne, though initially a bit aloof, decides to help him. This could start a relationship where they learn from each other, with Daphne learning about Harry's unique experiences outside the wizarding world and Harry getting a better understanding of the pure - blood society through Daphne.
Theodore Nott could be another main character. He might be a friend of Daphne or her future husband. In the fanfiction, he could be involved in the events leading up to the marriage, like helping with the preparations or being part of a sub - plot where he has his own feelings or motives regarding the marriage. Additionally, Luna Lovegood could make an appearance, adding her unique perspective to the story and perhaps being a friend to Daphne during this important time.
Daphne could be a shy and artistic girl. She might be into painting or writing, and she sees Harry as this source of inspiration. Maybe she first noticed Harry in an art gallery or a library, and that's when the crush started.
Well, perhaps it could be about their families being friends, so they are introduced as babies. Then as they grow up, they have a special bond that's different from others around them.