There are several main characters. For example, James Holden is a key figure. He often finds himself in the middle of major events and is known for his strong sense of justice.
Well, one of the main characters is Naomi Nagata. She is highly intelligent and plays a crucial role in the technical aspects of the story, especially when it comes to the ships and their operations. Another important character is Amos Burton. He is a tough and loyal guy who is always ready to fight for his friends. And of course, there's James Holden as I mentioned before. They all interact in different ways and drive the plot forward in the 'last expanse novel'.