The main character is likely Ash, as it's in the title 'ash trains alone fanfic'.
Since the title mentions 'ash trains alone', it's safe to assume that Ash is the main character. This Ash is probably on a training journey all by himself, and the whole fanfic would be centered around his experiences, growth, and challenges during this solo training.
Well, 'ash trains alone fanfic' could be a story where Ash decides to train by himself for various reasons. It could be that he wants to prove himself without the help of others, or he might be seeking a special kind of growth that can only be achieved alone. It could involve him facing challenges and overcoming them on his own during his training sessions, like dealing with difficult terrains or powerful opponents that he has to figure out how to defeat all by himself.
It could be a mermaid or merman who is alone in the ocean for some reason, maybe banished from their community.
The main character is Ash. But in some versions of the fanfiction, there could be new characters introduced that are related to the situation he's in. For instance, a hermit who lives in the forest where Ash is stranded. This hermit could either help Ash or be a hindrance, adding more depth and complexity to the story.
Well, in such a fanfic, Naruto might focus on mastering a new jutsu. He could be in a secluded area, like the forest near the village. He would practice over and over, facing challenges like controlling his chakra better. Maybe he'd also be thinking about how to become stronger to protect his friends and the village.
He could meet an old hermit who has some unique knowledge about chakra control. This hermit might be living deep in the forest where Naruto is training. The hermit could give Naruto some tips on how to better manage his chakra during his intense training sessions.
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.
A war veteran could be the main character. They might have come back from the war with PTSD and find it difficult to connect with people. At a community event, the crowded room full of happy and carefree people makes them feel even more isolated as they struggle with their own inner demons.
There could be a wise old hermit who lives in a secluded forest that Ash meets during his solo travels. This hermit might have a deep knowledge of Pokémon lore and give Ash some valuable advice.
Obviously, the main characters are Kurenai and Sakura. Kurenai is the trainer and Sakura is the one being trained.
Obviously, Lucy is one of the main characters. And the dragons would also be main characters as she is training with them.