Fathom by Elsa Jade

If Tritona’s war is over, who feeds the forgotten sharks of war?
Designed and trained to be a war-torn planet’s merciless killing machine, Sting was sent to the deeps when the battles ended. But the end of the fighting doesn’t always mean peace. Then one of the Wavercrest women from Earth goes missing, and he’s tasked with finding her. But how can this one small mission soothe the monster he was made to be?

She thought the seas were deep and dark and dangerous, but then she looked inside…
Lana Wavercrest has been running for what feels like forever. She thought she’d finally found her home on a faraway ocean world…only to discover that her heritage—the same unnerving powers that ruined her life on Earth—is considered a curse on Tritona too. Is there nowhere in the universe she can be herself?

But when Tritona’s enemy returns, they will have one last chance to decide the fate of worlds—and their lonely, drifting hearts.