Dragon Captain by Kendal Davis

Years ago, Kat signed a contract without reading it. Now her debt threatens to destroy her…
Kat was the beautiful, fun-loving Captain of her own boat. Her small business ferrying tourists in the Carribean came to a shuddering halt when her craft splintered apart on a desert world of dragon shifters.
Cobalt was the Captain of the Guards charged with bringing Kat safely home. He was everything a Caerulean dragon shapeshifter ought to be. Honorable, passionate, and powerful, he wanted above all things to claim Kat as his eternal mate.
When Kat learned that her debt could not be paid in any usual currency, she could no longer imagine a happy future for herself. She knew she had to face her mysterious creditor. If she challenged him alone, she might still hope to regain her pride and her sense of self-reliance. But without Cobalt at her side, she ran greater risks than she knew. Could she trust that he would be there when she needed him?