Sometimes in the Fall by John Van Stry

Finally free of Earth and all of his connections to it, David can now focus on his and Kacey's fledgling cargo company, and start considering his future goals as an engineer. There is still the small matter of the agreement he made with his grandfather, one of the richest men in the Solar System, but Dave knows his brother won't be solving the FTL issue anytime soon. So he's got time. However, there are forces on Earth that while David may believe he is done with them; they are by no means done with David. An escalating tit-for-tat is about to begin, over issues that will one day be worth far more money and power than David or anyone else can imagine. An escalation that will soon spiral out of all control and David will find himself with no choice but to unleash the horrors of war on an unsuspecting populace. One that will exact a price from his own flesh and blood before it is over.
Binding: Paperback / softback