Wicked Song by Ines Johnson

Once upon a time, a scheming sea witch gets her happily ever after.

Ursula was meant to rule the depths of the seas. As the rightful heir to ancient tides, her magic was born to command storms, sway currents, and shape the fate of the waters. But when she is betrayed and cast out of her kingdom, the siren is forced to survive by any means necessary… until the day a shipwrecked prince drifts into her arms—and into her plans.
Prince Eric has always lived under the crushing weight of duty—duty to his people, duty to his crown, and duty to a treaty with the sea kingdom that shackled him to a bride he had never met. But when he washes ashore, saved by a siren’s voice and a touch he can’t forget, he finds himself entangled not with the innocent princess he expected, but with a wickedly clever sea witch who tempts him with forbidden dreams—and dangerous promises.
Now, with a fragile treaty on the verge of collapse, pirates haunting the seas, and a kraken stirring in the deep, Ursula and Eric must navigate a world of treachery and temptation. Secrets will surface, alliances will shift, and two hearts caught between war and love must decide if they’re willing to risk everything for a chance at true freedom—and each other.

Wicked Song reimagines The Little Mermaid with sharp twists, stormy romance, and a heroine who was never the villain of her story at all.