Galen, a Syrena prince, searches land for a girl he's heard can communicate with fish. It's while Emma is on vacation at the beach that she meets Galen. Although their connection is immediate and powerful, Galen's not fully convinced that Emma's the one he's been looking for. That is, until a deadly encounter with a shark proves that Emma and her Gift may be the only thing that can save his kingdom. He needs her help--no matter what the risk.
Of Poseidon is the start of The Syrena Legacy series by Anna Banks.

Emma, who is half human and half Syrena, and her Syrena love, Galen, need time together. Alone. Away from the kingdoms of Poseidon and Triton. Emma's grandfather, the Poseidon king, suggests the two visit a small town called Neptune.

Neptune is home to both Syrena and Half Breeds alike. But Emma and Galen didn't sign up to be peacemakers between the ocean and land-dwelling, freshwater Syrena. They didn't bargain for meeting a charming Half Breed named Reed, who can barely disguise his feelings for Emma. And they especially didn't expect to find themselves in the middle of a power...

The princess didn't expect to fall in love--with her nemesis.

Princess Sepora of Serubel is the last Forger in all the five kingdoms. The spectorium she creates provides energy for all, but now her father has found a way to weaponize it, and his intentions to incite war force her to flee from his grasp. She escapes across enemy lines into the kingdom of Theoria, but her plans to hide are thwarted when she is captured and placed in the young king's servitude.

Tarik has just taken over rulership of Theoria, and must now face a new plague sweeping through his kingdom and...