The Time Keepers

Conden winced in pain. "It's fine, I've had worse." He brightened suddenly. "So what Element are you guys from?"
"Element?" I asked.
Conden looked confused. "Yes, Element. You know, Water, Fire, Air, Earth, Time, Metal? I'm from Water. Which one are you two from?"
I shook my head slowly, not following what he was saying. "I don't understand. We're not from anything, we're just... here."
Conden stared at us in disbelief. He shook his head. "No, you have to be from some Element, you wouldn't be on this island otherwise."

- - - - - -

For as long as she can remember, Sara has always lived on the island, if she can call it that (she's never seen the edge before). She's never met any human beings, and the only "people" she's encountered are ghosts. But that changes the day she finds the body in the woods.
Caiya has always been a bit of a loner. Prey don't make good company, and there aren't any other humans around to talk to. Until the day she hears the bloodcurdling scream.
Two girls living on the same island and each seeing another living human for the first time, it's not much of a surprise when distrust and suspicion drives a wedge between the two when they meet under unfortunate circumstances. But when the two do decide to join arms and figure out what really happened to the boy, they find that there is a far greater force at work, and that the world is much more than their island life.