Since I haven't read this specific fanfic, it's hard to say for sure. But it could be Harry Potter, of course. Maybe Hermione and Ron are also involved in helping the 'no longer alone' aspect, like they do in the original books, by being his friends and comrades.
In 'no longer alone harry potter fanfic', it could be that the main focus is on Harry himself. Maybe he discovers a group of people who truly understand him and accept him for who he is, which makes him feel no longer alone. It could involve his adventures with this newfound support system, facing challenges like the threat of Voldemort together, and growing as a person and a wizard in the process.
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.
Since I haven't read the 'alone on the water fanfic', I can't say for sure who the main characters are. But it could be a lone sailor, an adventurer, or someone who has been stranded on the water.
It could be a young trainer who prefers to journey alone. They might be the central character, facing Pokemon battles and exploring the world on their own.
Hermione could still be a common character. Even in fanfiction where Harry is alone, Hermione might be mentioned in his thoughts or in flashbacks as someone who has influenced him. For example, he might recall her advice on how to study magic when he is facing a difficult spell alone.
Hermione could still play a major role. She might be the first person to reach out to Harry when he finally enters the wizarding world. Since Harry grew up alone, he would be very different, and Hermione's inquisitive and helpful nature would be drawn to him. She could help him catch up on all the things he missed out on growing up alone.
It could be a Muggle - born protega. This character would face unique challenges as they try to protect the wizarding world while also dealing with their own identity issues. They might have friends among the Hogwarts students, and together they form a group to counter a new evil force that targets both Muggles and wizards.
Without reading it, it's hard to say. But it could feature the main characters from the original series like Harry, Hermione, and Ron as they are usually central in most Harry Potter fanfics. They might be the ones trying to solve the conundrum.
Since it's a fanfic, the main characters could be a mix of new and existing characters from the Harry Potter world. Maybe it has Harry, Ron, and Hermione in some sort of mentoring role to the new hunters. Or it could be entirely new characters who are on a journey of their own, exploring parts of the wizarding world that haven't been fully explored in the original series, like some hidden areas where they need to hunt for something important.
Most likely, the main character is the healer. They could be an original character created for the fanfic. There might also be appearances from well - known Harry Potter characters like Harry himself, Hermione, and Ron. Maybe the healer has to work with them to solve some sort of magical health crisis in Hogwarts or the wizarding world at large.