The Ocean's Heart — Debbie Cassidy

When the Sea King falls for the fake princess meant for his son. Royal by name only, Thalia Faircaster has lived her life by the sword, in service to an isle that is rapidly descending into ruin-the lands growing bitter and infertile, even as the population grows. When an alliance with the Northern Sea Realm promises her people a new home, Thalia willingly accepts the charge of escorting her adopted sister across the oceans to witness her wed to the Sea King's only son. King Vaarin's people are cursed with infertility, and a royal marriage with a blessed Faircaster royal will dispel the blight on his people. But the sea is a mercurial mistress, bringing a storm that tears Thalia's sister and crew from her, leaving Thalia for dead. Until King Vaarin finds her, mistaking her for the crown princess. He believes Thalia to be his son's betrothed, the key to restoring the fertility of his people, and his to protect until they reach safe waters. The alliance is vital to Thalia's people, and so she takes her sister's place. Willing to woo the prince and seal the agreement. So why is it the ancient king that makes her pulse race? On Lunaterra, fate is a cruel matchmaker-binding enemies, forging impossible alliances, and turning betrayal into desire. When kingdoms fall, curses rise, and war looms, love is the most dangerous game of all.