Well, Harry is the central figure. Then, there could be an experienced sailor who acts as a mentor to Harry. This mentor helps Harry understand the unwritten rules and traditions of the navy. And perhaps there's a female character, a navy medic, who Harry has a bit of a romantic interest in and she also plays an important role in the story.
In this fanfic, Harry is a main character. There may be a group of his comrades in the navy that are also important characters. They might be involved in various activities together, like going on patrols or participating in naval drills. And there could be a senior admiral who makes important decisions that affect Harry and his unit.
Obviously, Harry is one of the main characters. There might also be his commanding officer, who could be a strict but fair person guiding Harry through his naval career. Another main character could be Harry's best friend on the ship, someone he shares his thoughts and experiences with.
There might be some original characters created for the fanfic. For example, a wizard who has prior experience as a Navy Seal in the Muggle world and now brings those skills back to the wizarding world. He could be a mentor - like figure, teaching other wizards about things like discipline and combat strategies. Or maybe Ron could also take on a more prominent role, with his loyalty and courage being emphasized in a Navy Seal - inspired context.
Well, apart from Harry, there might be an older, experienced sailor. This character has been in the Royal Navy for years and has a wealth of stories and knowledge to share with Harry. Then there could be a group of fellow trainees who are all going through the same experiences as Harry. They support each other, but also compete in a friendly way. And there could be a mysterious figure on the ship, perhaps a stowaway or a spy from another country, which adds an element of mystery and danger to the story.
It's possible that Hermione could be a main character too. She might interact with the Navy Seal character, perhaps learning from their combat and strategic thinking. Another likely main character could be a Navy Seal team leader who gets involved in the wizarding world's battles and forms an alliance with the Hogwarts students.
I don't know for sure as I haven't read it. It could be the captain of a ship, or a young recruit who has to prove himself in the Atlantic navy.
Some RWBY Navy fanfics also introduce original characters. These new characters can be the captains or crew members of the naval vessels. They interact with the RWBY characters, creating new relationships and storylines. Their presence can bring fresh perspectives to the fanfics.
I don't know for sure without reading it, but I would expect the main characters to be Navy Seals. Maybe there's a senior officer leading the team, and some younger, more inexperienced Seals who learn something important during the Christmas - related events in the story.
In 'Harry and Teddy fanfic', the two main characters are Harry and Teddy. Harry is the one who has been through so much in the wizarding world. He has a sense of responsibility towards Teddy. Teddy is a character full of possibilities. He's the product of a tragic event (his parents' death), and Harry's presence in his life is like a guiding light. Their personalities, Harry's wisdom and Teddy's eagerness to learn, are often explored in these fanfics, which makes for very engaging stories.
In some fanfics, there could be magical animals other than crows. For instance, a wise old owl that serves as a mentor to Harry. The owl could give Harry advice on how to deal with various situations, such as when he is facing a difficult choice or when he is in danger. These additional characters add more depth and variety to the fanfic stories.
Then there might be some souls that Harry has a special connection with. These souls could be recurring characters, each with their own backstory and personality, and their interactions with Harry would drive the story forward in different ways.
Harry is the central figure. But there could also be other students who become aware of Harry's situation. For example, Hermione might be a key character. She could be researching ways to either help Harry or deal with the consequences of his transformation. And then there could be a new character, perhaps a magical cat - keeper in the Forbidden Forest who has some knowledge about cat - like magic and can offer assistance to Harry.