Sweet Obsession by Katee Robert

Icarus may not have flown particularly close to the sun, but he has fallen…right into the rough hands of Olympus’s own Poseidon. Being held captive by the gentle giant wouldn’t be so bad if Olympus wasn’t on the eve of destruction…or if Poseidon stopped looking at him with those irresistibly stormy eyes.
Poseidon doesn’t have time to babysit his increasingly bratty prisoner, but he has no choice: Olympus is officially at war, and someone has to keep their best bargaining chip out of harm’s way. The thing is, the longer Poseidon is with Icarus, the more he starts to care for his sworn enemy…and the more he realizes that Icarus isn’t the villain he’s been made out to be. There’s a warmth to him, a vulnerability, that Poseidon finds difficult to ignore or deny.
Now with Circe and the Aeaens at the gate and Olympus a hair’s breadth away from falling, Poseidon will have to make a difficult choice: about himself, about his allegiances, and about the man who woke his heart from its long slumber only to threaten to break it for good…