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.
I haven't actually read this specific fanfiction, but it's a very dark and disturbing concept. In the normal 'Harry Potter' universe, Harry and the Weasleys are friends. So this fanfiction probably involves some sort of dark plot twist or alternate reality where Harry turns against them for reasons that could range from being influenced by dark magic to some misinterpreted prophecy or a huge misunderstanding.
In this fanfiction, the betrayal might also stem from jealousy. Harry is often in the spotlight, and the Weasleys, who have always been a big family but not always in the center of attention, could let envy get the better of them. This could lead to actions that Harry perceives as betrayal, like spreading rumors or withholding support when he needs it most.
He will most likely meet Sirius Black. Sirius is an important figure in Harry's life and his presence at Grimmauld Place is quite significant. They could have a deep conversation about Harry's anger and what to do next.
They might be shocked and sympathetic. The Weasleys are a kind - hearted family. When they see Harry's scars, which are symbols of his difficult past, they would likely show concern. For example, Mrs. Weasley might immediately fuss over him, asking how he got them and if they still pain him.
The Weasleys are likely to be horrified. They are a warm - hearted family. Mrs. Weasley might immediately take on a motherly role towards Harry, perhaps making him his favorite foods and fussing over him. Mr. Weasley could become very protective, ensuring that Harry is safe from any further harm. The siblings, like Ron, might be angry that Harry had to endure such abuse and vow to always have his back.
They would likely be shocked and angry. The Weasleys are a kind - hearted family. They might immediately take Harry under their wing more protectively, like Molly Weasley would probably start fussing over him even more, making sure he has enough to eat and a warm place to sleep.