What do you mean by "people treated her like she didn't know any better"? I'm curious.
I personally feel like the whole orphan-running-away-from-the-horrible-orphanage bit has been done to death, but since this is a fantasy story, it might work. It all depends on how it's done.
I'm not sure how a fawn and a pixie/fairy could save a much larger person from something dangerous. Do they use magical powers? Is the pixie/fairy the size of a normal person? I would like to know more about this world and the creatures that inhabit it.
"An intellectual says a simple thing in a hard way. An artist says a hard thing in a simple way."
-Charles Bukowski "And by the way, dearie, your punctuation sucks canal water!"
-The ghost of Vivian Vance