Rugged Rock by Ellie Pond

I thought we’d escaped.
Wrong. Oh, so wrong.
The five of us—including my mates and protectors—beat the enemy mermen in the Boston battle. But we’ve yet to win the war.
A haven turns into a New Years’ hell. Kidnapped and separated, with a life put in jeopardy, we have to combat a mystical kind of greed.
If that weren’t enough, I’ve discovered I’m far more than a mermaid or even a princess, and my long-lost family brings its own set of dangers to our already perilous situation.
I must protect my mates from the vampires who seek to enslave them, vengeful fae, and—perhaps most dangerous of all to my pod—my own flesh and blood.