There's no way to tell without reading the fanfic. It could be a crossover fanfic, in which case it might combine characters from different works. Or it could focus on minor characters from the original work and give them a chance to shine during this 'summer like no other'.
I'm not sure specifically as it depends on the particular fanfic. But they could be young hippies, musicians, or artists who were part of the Summer of Love scene.
Since I don't have the book in front of me, it's hard to say exactly. However, based on the title, there could be characters who are deeply affected by the Indian Summer season. Maybe an old man who has seen many Indian Summers and has stories to tell. There could also be young characters who are just starting to experience and understand the significance of this special time.
Since I haven't read 'Summer Days and Other Stories', it's hard to say for certain. However, in stories with such a title, we might expect to find characters like a young couple spending their summer together, a family on vacation during the summer months, or perhaps a solitary figure who finds solace in the summer days. There could also be local characters in a small town where the summer stories are set, such as a friendly shopkeeper or a beachcomber.
Sometimes, new and younger characters also take the spotlight in these fanfics. For example, Ms. Marvel might join the Avengers during their summer adventures. Her fresh perspective and new powers can add a different dynamic to the group. Also, characters like Doctor Strange might be involved if there are magical elements in the story, which could be related to some summer - themed mystery or threat.
Well, it could be a story where the summer is filled with extraordinary events that are not common in normal summers. Maybe it involves the characters going on an unexpected adventure, meeting new and interesting people, or facing challenges that are only possible during that one special summer. For example, in a fanfic based on a superhero universe, the heroes could have a summer where they discover new powers or face a villain with a strange summer - related plot.
It might be that the characters have unusual experiences during the summer. Maybe they encounter mythical creatures or find themselves in a parallel universe. Or, it could be that the relationships between the characters undergo profound changes in a way that's never been seen before.
Well, in the 'Girls in Their Summer Dresses' story, the man and his wife are likely main characters. They are central to the plot as it seems to be about their relationship and the man's wandering eye when seeing other girls in their summer dresses.
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 main characters would be Austin and Ally, of course. Austin, the talented singer, and Ally, the brilliant songwriter. They are the heart of any Austin and Ally story, including one set at a summer camp.
The main characters in the 'Harry Potter 4th Summer Fanfic' could be Harry Potter, of course, as the central figure. But Fleur Delacour could be introduced early in the summer, maybe she has some business at Hogwarts or in the wizarding world near where Harry is. Viktor Krum might also make an appearance, perhaps he is scouting the area where the Triwizard Tournament will be held. And Ginny Weasley could be a main character as well, she might be developing her own magical abilities and sharing some of her insights with Harry.