The main characters are the same as the other two books, except that we see a bit more of the two new characters from Kwaide; Ledin and the visitor.
Ledin crept into Kwaide as one of the Kwaidian pilots who Grace trained up. He is nice, sturdy, dependable, and kind. He grew up in the uninhabitable zone, like Six, but he unfortunately lost his only sister during that time. He is greatly liked by the other Kwaidians, and has taken over the running of the Kwaide International Orbital Platform.
The visitor is another character who first came into the series in Kwaide. He is a traveler from the Dessite system, and he and Six rub each other up completely the wrong way. The visitor thinks that no category 3b species can be of much help to category 2 species, such as the Dessites and Arcan. Six does not agree with this!
One of the new characters in Xiantha is the canth keeper. He becomes rather important to Grace, who loves the philosophy of the Xianthans, and feels very much at home on their planet. He is an important man on the planet, being in charge of the well-being of the canths, but circumstances make him even more important as the story continues.
The ticket collector, on the other hand, is just a cameo character, but rather charming. He is so delighted when he gets another colour; so determined not to make a mistake. He is fun.