MY first suggestion is to avoid the phrase 'no Mary Sues' because Mary Sue is a subjective term, what is Sue to the reader may not be Sue to the reader so let them decide for themselves. Instead perhaps make a summary that tells something about the story, a blurb about the story like the one you find on the back of a dvd rather then an AN from you to the reader.

An excellent intro, good vocabulary and imagery. I can see it although I can't imagine a place that rains every night to be called a desert. Kind of the defining thing about a desert, little rain.

The way you set up your fic is good, and also laying way for the plot already. I particuarly like the 'with no one left to fear we began to fear each other.' A very human state of mind. Dialogue feels a bit scripty but I'd have to see more to be sure. It feels fairly natural though. The characters blood limit is a good one, no ridiculous cliches of wings or unbeatable power or the like.

A good start, but more will tell.

what does "OC" stand for?