The Cassandra Kresnov in "23 Years On Fire" is more grown up and much more dangerous than the kick-ass killbot who'd rather surf than fight that I met in the first three books of the series.
This Cassandra Kresnov has had time between political/military crises to think about who she is and what she wants. She's also been joined by other high-designation GIs (artificial people, built as sentient weapons) who have left the League to for freedom in the Federation and she's starting to understand what GIs who are not doomed to die young in battle might be capable of.
Cassandra (Sandy to her friends) has been in battle for most of her life, prompting the journalist writing her biography to propose "23 Years On Fire" as the working title.
She had already decided that the League, which treated GIs as disposable weapons, was not worthy of her loyalty. In this book, although she remains loyal to the Federation that has given her a home, she realises that her interests and theirs might diverge. She's going to have to choose sides. Again.
As with the previous books, "23 Years On Fire" is packed with action (it opens with Sandy and her small troop of GIs leading a covert assault on a planet, that is doing very bad things to its citizens), interspersed by periods of reflection and character building.
Except that, this time, the technology has become more powerful and Sandy's reflections include the possibility that she may have to do things that the Federation doesn't want her to do. In the previous books, Sandy was the exception. She was the GI trying to become more human or at least be accepted by humans. In this book, Sandy is a gifted GI amongst other GIs with a life beyond war and her closest human friend has been augmented to the point where she can match the performance of some GIs. The idea of a world that includes people who are more than human or other than human is becoming a reality.
Now the war is over, the League is imploding and some worlds are going rogue. When Sandy learns that one of these worlds, ruled by crime lords in business suits, is experimenting with new GIs who have no free will, she feels obliged to do something.
In the process, she finds out who her real friends are, discovers the real origins of GI technology, and finds herself leading "her people" against an evil, repressive regime that has created a nightmare world.
Sandy starts to look into why some humans behave in ways that don't fit the facts of their situation. She describes "Compulsive Narrative Syndrome" to account for how the stories that we tell ourselves have more impact on our beliefs than the facts we have available. This seemed such a plausible idea that I did a separate post on it: "Compulsive Narrative Syndrome – if it doesn’t exist, it should."
All in all this is a much darker, more sophisticated book than its predecessors without losing any of the wit, humanity and "let's blow lots of stuff up" action that made the other books enjoyable.
The change surprised me until I checked the publication dates. The first three books "Crossover", "Breakaway" and "Killswitch" were published between 2001 and 2004. Then Joel Shepherd put Cassandra Kresnov to one side and published the four book "A Trial Of Blood And Steel" fantasy series. He has only recently revisited Cassandra Kresnov. "23 Years On Fire" was published in 2013, followed by "Operation Shield" in 2014 and "Originator" in 2015.
The break has freshened up the series without breaking from its roots. I'm looking forward to seeing where the next two books will take me.