Fallen by Melissa Scott PB

Nic en Doroney was promised an education and an academic career in exchange for sharing the nanite burden she carries in her bloodstream. Instead, the Novilis family broke that bargain, and now Nic is captain of a small starship, competing with larger businesses by using illegal Ancestral technology to chart her way through the adjacent possible. But when Rejane Novilis re-enters her life, Nic is unable to resist the chance to work with her again, even if it means challenging the malevolent AI who have already destroyed human society once before.