Augustus P. Dechantagne is the third of the Dechantagne siblings in the Senta and the Steel Dragon saga and is probably the least important. He is least important to the story and he is least important in his own life. Augie is a happy go lucky rake-- the kind of guy that everybody loves and who can get away with anything.
Augie plays a big part in Book 0 and Book 1, particularly the latter. When we meet him in Book 1, he is in Birmisia. This is important because as a result of his knowledge, his family decides to build a colony there. Augie is a lieutenant in the artillery, so he is obviously intelligent, but being in the son of a wealthy family, he is generally unambitious (the exact opposite of sister Iolanathe) and is never serious about anything (the exact opposite of brother Terrence).
Lt. Arthur McTeague
McTeague was created for Book 0, and he doesn't appear again in the series. He is Augie's co-commander and friend. We don't learn much about McTeague, other than he is a likeable friendly guy, like Augie. The name Arthur comes from my own family-- a cousin and a grandfather, both of whom I am very fond. McTeague comes from the book McTeague by Frank Norris, about a sociopathic dentist. I read it in college and liked it.
Colour Sergeant Bourne
I needed a sergeant for my two lieutenants, and who better than Colour Sergeant Bourne. He is named of course, for the character (based on a real person) in the movie Zulu. This is especially fitting, since Zulu is not only one of my favorite movies of all time, but was an inspiration for the combat scenes in Book 1: The Voyage of the Minotaur.