In some fanfictions, Harry might change physically. He could have grown taller or more muscular from any summer training he did. For example, if he was secretly practicing Quidditch on his own, it could have affected his physique. Also, mentally he could have become more mature. Maybe he spent the summer reading advanced magic books and this broadened his understanding of magic, making him more confident and less impulsive in his actions.
Well, physically he could change too. Fanfic writers might describe him as growing taller or stronger during the summer break. Emotionally, he might deal with his past traumas better. For example, if he had nightmares about Voldemort, he could learn to overcome them, perhaps through some new magical techniques he discovers or with the help of his friends. This could make him more resilient and less haunted by his past, which is a significant change for his character.
Perhaps it focuses on the changes in Harry's relationships. He might grow closer to some friends while drifting apart from others. For example, his bond with Hermione could strengthen as they explore some new magical mystery together during that summer. And his relationship with the Dursleys could also take a turn, like they finally start to show a bit of understanding towards him.
It could center around the changes that occur in the wizarding world during a particular summer. For instance, new spells could be introduced, or there could be a shift in the relationships between different magical families. It might also be about how the Hogwarts students adapt to these changes when they return to school after the summer.
It could also focus on some of the minor characters from the original series. For example, Neville could be a main character in this fanfic and his growth and change during the summer could be the main focus. Or Luna, with her unique perspective, could be in the center of all the happenings during that summer of change.
The important characters could also include some of the Hogwarts professors. They might be keeping an eye on Harry during the summer, or there could be a plot where one of them needs Harry's help. Even some of the minor characters from the original series, like Neville or Luna, could pop up and have an impact on Harry's summer. They could bring different perspectives or abilities that contribute to the overall theme of change in the fanfic.
Well, without actually reading the fanfic in full, it could potentially involve Harry Potter experiencing personal growth during the summer. Maybe he discovers new magical abilities or forms deeper friendships. It might also include changes in his relationship with the wizarding world, like getting involved in new secrets or plots.
Emotionally, he could have changed a great deal. If in the fanfiction he faced some personal challenges over the summer, like dealing with the loss of a friend or a new family situation. This might have made him more withdrawn or on the contrary, more determined to face his enemies. For example, if he discovered some secrets about his family that made him question his identity, it would have a profound impact on his emotional state.
He could work at Weasleys' Wizard Wheezes. He has a good relationship with the Weasley family, and it would be a fun place for him to work, helping with inventing and selling all kinds of magical pranks and toys.