Late 1980s/early 1990 Space Saga. Female Captain. Female first mate/security who had been kicked out of the Emperors' Immortals military force (including her lover). They start at a space station, I believe they take on a stray young runaway child before leaving the space station.
There is a rebellion against the emperor, and it's led by a very charismatic leader(there may be an aspect that no one really knows what he looks like). The strategy so far by this rebellion is moving around the outer ring planets of empire in an inward spiral.
The protagonists eventually run into the rebels. (I can't remember if they are caught, or this is the only way to make some type of deal etc). The twist here is when they meet the rebel leader, he's the guy the First Mate had an affair with and got kicked out of the Immortals! She didn't know he'd led the rebellion.
The book sizes were normal for the time, about the thickness of a Harry Harrison scifi novel. Well written, good action/writing/some good real life humor from the characters during the adventures.