Her Fated Wolf Protector by Meg Ripley

Serena:
My life at the castle has been a sheltered one. Annoyingly sheltered. Sure, the blooming roses and constant magical presence is cool, but the constant watchdog from the Shifters and the Mer-People is very old.
The other future High Alphas have moved on, faced darkness, found their Mates, and started families. And here I am sneaking off with my best friend just to go for a swim. My Mermaid aches for the free ocean, and my heart knows where it’s destined to be.
Sneaking out in the middle of the night to rescue my best friend from the Dark One was not where I thought I was destined to be.
But it was my fault.
And I wasn’t traveling alone. Ellis won’t leave my side, and there’s a massive part of me that doesn’t want him to. He ticks me off in all the right ways, and my magic is expounding beyond my imagination. Fate brought us together, but I’m not sure it can keep us together.
Not with the Dark One planning the end to life as we know it.
The future of all living creatures hangs in the balance, and it turns out, I’m more important than I thought. But can I rise to the occasion? Or will the ancestral right of Alphas go down in a flurry of dark magic and war? The answer is in me. But I don’t know how to find it.