Well it's not much help, I know. But Aric Jorgan mentions that the Trooper was pretty much the star student, you know, top of his class and all that. So that's sort of a background. I do remember something being said about the IA as well, but, I just can't recall. The Inquisitor is the only one who pretty much gets solid confirmation on some of his past, a decendent of Kallig "Flesh of my Flesh" Specterface, but even then the Inquisitors background is hardly revealed (Except when you talk to your second companion and your Inquisitor can mention he became a slave afters shooting at a racist Imperial, mind you I got this as an alien Inquisitor, not sure if it's the same for humans)