Vampires Vs. Aliens, Book One: Arrival - Vampires Vs. Aliens, #1

They came from a dying world to steal the Earth's water, a scarce resource they need to survive but didn't anticipate resistance from the vampires. The aliens' plan would doom the human race... And with no humans or other life left on Earth, the planet's furtive vampire population would be deprived of its sole food source. Now the vampires must wage a secret war against the invaders while hiding their own existence from the humans. In Book 1: Arrival, teenager Courtney Cartwright meets handsome young Nicholas and attractive Kevian, unaware the former is a vampire and the latter is an alien warrior prince from the planet Hyperion.
Nicholas resides in a boarded-up mansion on the outskirts of town with his "family" of vampires, while Kevian and his sister Princess Kira are the first of many Hyperions to depart their command ship orbiting the dark side of the moon to assimilate on Earth.