Of course, there are often original characters in Harry Potter trains fanfiction. These could be new students who have their own secrets or powers. They might interact with the well - known characters, and sometimes they can even be the key to solving a mystery on the train, like uncovering a plot against Hogwarts that starts on the Hogwarts Express.
Obviously, Harry Potter himself is a main character. Since it's about him being alone on the train, he is the central focus. But sometimes, other characters like Dumbledore might make an appearance in his thoughts or as a sort of guiding force. For example, Harry could be reminiscing about Dumbledore's advice while on the train.
There could also be new characters introduced in the fanfic. Maybe a new mentor figure who guides Harry in his training. This character could have unique magical abilities and knowledge that they pass on to Harry. Another possibility is an antagonist who tries to disrupt Harry's training for some reason, adding conflict to the story.
Harry is the central figure, but there might be some new characters introduced in the fanfic. For example, an old wizard who lives on the outskirts of Hogwarts and has some unique knowledge about magic that Harry discovers. This character could become a sort of mentor, even if from a distance, as Harry trains himself using the knowledge he imparts. Also, there could be antagonists like some students who are jealous of Harry's self - improvement and try to disrupt his training.
I'm not sure specifically as it depends on the author of the fanfic. But it could include the classic Harry Potter characters like Harry, Hermione, and Ron. They might be on the train for some special reason related to their fight against Voldemort or some other new threat.
Sirius Black could be a trainer. Sirius, being Harry's godfather, would be highly motivated to train Harry. He could use the time - turner to go back to a time when he was at his peak in terms of combat skills and pass on his knowledge to Harry, especially in the areas of dark - wizard fighting and survival skills.
In 'Harry Potter Rebel Fanfiction', characters like Sirius Black can be important. He was a rebel in the original story, and fanfiction can explore more of his rebellious nature. Severus Snape could also be a character in such stories, especially if the fanfiction delves into his complex relationship with the Death Eaters and his own form of rebellion against Voldemort. And don't forget about Dumbledore. There could be fanfictions that explore his more secretive and perhaps rebellious actions behind the scenes that we didn't fully see in the original series.
Harry Potter himself is often a common character. He could be at the camp as a mentor or a special guest. Hermione Granger might also be there, sharing her vast knowledge of magic with the campers. Ron Weasley could be around too, getting into some comical situations. Additionally, new characters created specifically for the fanfiction might be present, like a young wizard who is a bit of a troublemaker at the camp.
Hermione Granger is often a common character. She would likely be at the top of her class in the university setting, continuing her thirst for knowledge. Harry Potter himself might also be there, perhaps as a teaching assistant or a more experienced student helping others. Ron Weasley could be around too, still providing his loyalty and humor. And Luna Lovegood might be involved in some of the more unique and esoteric studies at the university.
Goblins are essential characters in Gringotts - related fanfiction. They are the ones who run the bank and have their own set of rules and personalities. Some fanfictions might introduce new goblin characters with unique traits. And then there are the dark wizards or witches who could be trying to break into Gringotts for their own nefarious purposes, like Bellatrix Lestrange who had an interest in the Lestrange vault.
Well, of course, Harry Potter himself is a common character as the heir in these fanfictions. Hermione is often there too, helping Harry figure out the implications of his new status. Ron may also be present, providing support and some comic relief. Sometimes, characters like Dumbledore play a key role as well, guiding Harry through the revelations about his heritage.