Caged By the Ruthless Thief by Ellie Pond

Thrust into a realm of mystery and allure, doctoral student Annabelle confronts the dual reality of curse and blessing that her mermaid blood brings, as she navigates the intrigues of the Veiled City.
Eros, the enigmatic thief caged by his dark past and ruthless decisions, stands at the crossroads of redemption and ruin. Blackmailed into an assassin’s shadowy embrace, he’s tasked with a deadly mission—eliminate Nico, the merman commander whose calloused hands and tender heart awakened the mermaid within Annabelle. Torn between lethal duty and burgeoning obsession, Eros must decide whether to embrace the shadows or fight for love.
As Nico embarks on a perilous quest in treacherous waters, the bonds of love and loyalty are tested. Holter, the steadfast geminae, and Castor Drakos, a scion balancing power and passion, are entwined in the dance of destinies, each harboring secrets that could either strengthen the bonds of love or shatter the foundations of their world.