The Maker's Mask: Book One of Requite — Ankaret Wells

Tzenni Boccamera wasn't a soldier or a diplomat. She was an engineer. But when Tzenni's sister Catha was captured by soldiers from a rival Spire, there was no one else to go to Catha's rescue.Tzenni didn't expect the rescue to involve a sarcastic bodyguard, a plot to bring down the Spire, or an alien species. And she certainly hadn't meant to fall in love. . .