The Oceanographer's Private Siren

Renowned marine biologist Moriarty, fixated on an immortality serum, wiped out Finnian's merfolk clan, then posed as his savior and locked the lone survivor in an underground tank. For three months he fed Finnian false tenderness while stealing his scales and dependence. When the lies come out, Finnian turns from docile captive into a defiant avenger willing to risk death to escape. Moriarty's possessive obsession keeps dragging him back, and when black-market sponsors come to claim the specimen, he shields Finnian with his own body.