There might also be a powerful leader figure who either contributes to the downfall or tries in vain to prevent it. Their actions and decisions would have a major impact on the story.
The most important characters in 'the cay historical fiction' are Phillip and Timothy. Phillip is a young boy who has to adapt quickly to the new environment of the cay. Timothy, on the other hand, is an experienced man. He has wisdom about the sea, fishing, and building shelters. He not only takes care of Phillip but also helps him see beyond racial differences. There are also some minor characters like the sailors at the beginning of the story that set the stage for the adventure that Phillip embarks on.
I'm not entirely sure without reading the book, but usually in historical fictions, there are protagonists who drive the story forward. There might be a strong female character who is at the center of the events, perhaps a woman who has to face great challenges in that historical period.
There might be a diviner as an important character. This person could have special abilities to see the future or understand hidden things. There could also be a historical figure, perhaps a leader or an influential person in the society depicted in the story.
One of the main themes could be the passage of time and how it affects characters and events. In many historical fictions, the changing times play a crucial role in the development of the story.
The gentleman himself is obviously a very important character. His actions, thoughts, and reactions drive the story. The hotel staff also play important roles as they interact with him and help shape his experiences within the hotel.
Adam is obviously the most important character. He is the protagonist whose journey we follow throughout the story.
Mattie Cook is a very important character. She is the main character around whom the story revolves. She experiences a great deal of growth throughout the story as she faces the challenges of the yellow fever epidemic.
Miss Thomas is also very important. She's kind to Bud when he arrives at the place where he thinks his father might be. And Herman E. Calloway, who turns out to be an important figure in Bud's search for his family. Bud initially thinks he's his father but later discovers he's his grandfather.
Thomas Cromwell is extremely important. He is the central figure around which much of the story revolves. King Henry VIII is also crucial as he is the king whose court is the setting for all the drama. Then there is Anne Boleyn, whose relationship with the king causes a great deal of upheaval.
The most important character is Jim, the young boy. He is the protagonist and through his eyes we experience the story. Then there are the soldiers, both Japanese and Allied, who play important roles in the power dynamics and the overall atmosphere of the story. There's also Basie, who befriends Jim at some point and they have a complex relationship.