The Tether

"Beauty and the Beast meets Dracula in this tension-filled sequel with a strong female lead."
Ruby Spencer hasn't slept in nine years.
Which makes her dream-like visitor more peculiar. Liora, an alluring immortal, professes to know the source of Ruby's unique blood: blood that saved humankind from a bioweapon; blood that enabled her to become the government's warrior against ZOM-B.
One of Ruby's blood donors is the King of Darkness. And that's not the only revelation sending shivers down her spine. With animals dwindling on Earth and his planet, the king-an ancient vampire with unfathomable powers, has set his sights on a new blood source: humans on Earth.
If Ruby is to defeat the most odious force ever encountered, she must embrace her legacy as The Tether and awaken her gifts. But time is running out for humankind and her family.
Survival teeters in the balance.
Note: The Tether can be read as a standalone or as Book 2 of The ELI Chronicles. (The One and Only is the first installment in the series.)