The Ministry of Magic could also be the main antagonist in this case. If the Ministry is corrupted or under the influence of dark forces, they could manipulate Harry's friends. They might convince his friends that Harry is a danger to the wizarding world order, and his friends, being naive or misinformed, end up betraying him.
One consequence could be a breakdown in their friendship. His friends might feel hurt and start to distance themselves from Harry. For example, Hermione, who is very loyal, might be deeply offended if Harry constantly doubts her.
In some fanfiction, the author might create a plot where Harry has been betrayed before. So, he has trust issues even with his friends. For example, if he was tricked by someone who seemed like a friend in the past, it could make him more cautious and less trusting in new situations with his real friends.
Well, usually in such fanfictions, Harry might face a lot of emotional turmoil and have to find his way alone to overcome the betrayal and the challenges that come with it.
Harry's acceptance of his destiny would make his relationships with his friends more complex. On one hand, they would be proud of him. But on the other, they would have to adapt to his new role. His friends would need to find their own places in his journey. Hermione might focus more on researching ways to help Harry fulfill his destiny, while Ron could become more of a protector, guarding Harry from distractions. This evolution in their relationships would be a crucial part of the fanfiction's story.
Later, he could become depressed. Harry has always valued his friends highly, so losing them would be a huge blow. He might isolate himself in his dormitory, not participating in school activities as much. He would probably be constantly thinking about what went wrong and how to fix it.
One possible plotline could be Harry feeling extremely isolated and trying to find new friends outside of his usual circle. Maybe he starts to focus more on his studies and discovers new magical abilities on his own.
Hermione would probably be very curious at first. She'd want to research all about the Peverell family to understand the significance of Harry's decision. Ron, on the other hand, might be a bit more confused and a little worried that Harry is trying to distance himself too much from their group. But overall, they would support him because they are his true friends.
His friends might be initially confused. They're used to seeing Harry's face clearly, so a mask could create a sense of distance. Hermione, for example, would probably be very curious and try to find out the reason behind it right away. Ron, on the other hand, might be more laid - back at first but would also start to worry if Harry didn't explain soon.