Well, one possible plot could be that Harry would finally experience a warm family life. He'd grow up with the Weasleys' chaos and love. He might learn more about magic in a different way than at Hogwarts, with Molly Weasley's home - cooked meals and Arthur's fascination with Muggle objects influencing him. The Weasley siblings would become his true brothers and sisters, and they'd all get into various adventures together around the Burrow.
Harry's character would likely become more light - hearted. Growing up with the Weasleys, he'd be surrounded by laughter and love. He might lose some of his brooding nature. His self - confidence could grow as he is part of a big family that supports him unconditionally.
In this fanfiction, Hermione might experience a whole new family dynamic. She could become closer to the Weasley siblings in a different way. For example, she might be more involved in their family traditions right from the start. Maybe she would get to participate in Weasley family meetings and have a say in family matters like a true family member.
In some of these fanfictions, a really cool plot twist is that Fem Harry has an unknown magical heritage on her mother's side that gives her powers that are very different from normal wizarding abilities. This makes her stand out even more in the Weasley family. The Weasleys then have to deal with the jealousy and envy of other wizarding families who want to use Fem Harry's powers for their own gain. Also, she might be able to communicate with the portraits in Hogwarts in a way that no one else can, which leads to her getting crucial information about the school's history and secrets.
In stories where Fem Harry is adopted by the Weasleys, her character development is quite complex. Initially, she's a bit of a lost soul, trying to fit into this big, chaotic family. But the Weasleys' love and acceptance start to change her. She becomes bolder in standing up for what she believes in. Her relationship with each Weasley family member also shapes her. For instance, learning from Molly's motherly nature and Arthur's curiosity about the Muggle world. As she gets older, she might use her unique position as both a Potter and a Weasley (in a sense) to bridge gaps between different wizarding groups, showing her growth from a lonely girl to a confident young woman with a purpose.
In the fanfiction, it could start with Hermione having a falling - out with her own family due to her magic. The Weasleys, seeing her distress, offer to adopt her. As a part of the Weasley family, Hermione would be involved in all their family traditions. She could bring her intelligence to help with family matters, like helping with George's business by using her logical thinking. And her relationship with Ginny would become even closer, like true sisters, sharing secrets and having girl - talk that they didn't have much opportunity for before.
One possible reason could be that Harry has post - war trauma. He might have seen so much death and destruction during the war that he doesn't want to bring his darkness and pain to the Weasleys. He may think that staying away is a way to protect them from his own emotional turmoil.
At first, the Weasleys might try to reach out to Harry. But as he continues to avoid them, they could start to feel rejected. This might lead to some resentment building up, especially among the younger Weasleys who don't understand why Harry is acting this way. For example, Ron might be really frustrated as he considered Harry one of his best friends.
I'm not sure if it's a popular fanfiction. It's such a dark and against - the - grain concept for the 'Harry Potter' fandom that it might not have a large following. Most fans are used to the positive relationships between Harry and the Weasleys in the original series.