Hartsuyker, Linnea. Half-drowned king series.

Six years after The Half-Drowned King, Ragnvald Eysteinsson is now king of Sogn, but fighting battles for King Harald keeps him away from home, as he confronts treachery and navigates a political landscape that grows more dangerous the higher he rises. Ragnvald's sister Svanhild has found the freedom and adventure she craves at the side of the rebel explorer Solvi Hunthiofsson, though not without a cost. She longs for a home where her quiet son can grow strong, and a place where she can put down roots, even as Solvi's ambition draws him back to Norway's battles again and keeps her divided from her brother. As a growing rebellion unites King Harald's enemies, Ragnvald suspects that some Norse nobles are not loyal to Harald's dream of a unified Norway. He sets a plan in motion to defeat all of his enemies, and bring his sister back to his side, while Svanhild finds herself with no easy decisions, and no choices that will leave her truly free. Their actions will hold irrevocable repercussions for the fates of those they love and for Norway itself. The Sea Queen returns to the fjords and halls of Viking-Age Scandinavia, a world of violence and prophecy, where honor is challenged by shifting alliances, and vengeance is always a threat to peace.--