Fallen Rebel by C.G. Blaine

Cass:
Watchers exist by one rule: keep your Nephilim alive. No matter what.
Protecting, following, watching from the shadows, I’ve served my time. Now, all that stands between me and returning home is her.
Hannah Kelley. The last of her line. My final charge. So long as she stays breathing for the next fifty to seventy years, I’ll have completed my punishment. No longer a Fallen.
Except now, she knows who I am. She knows what I am.
And I have no doubt she’s about to make my existence an absolute hell.

Hannah:
I lost everything I loved at once, my world ripped apart in an instant.
I’ve been alone ever since. At least, I thought I was until I met him. A guardian angel. My Watcher. The immortal asshole interfering with every aspect of my life.
Once Cass steps out of the shadows, I have no way of putting him back. Even though I desperately want to. He’s not exactly thrilled with my existence either. I’m keeping him from the eternity he’s been waiting for after all.
But whether we love or hate each other, our fates are intertwined—his forever tied to my life.
And when Cass decides he wants that forever to include me, I fear for anything in Heaven or Hell that might try to get in his way.