So to better picture the drawing before drawing it up I think of a story to sort of help you get into it. Or see what I'm going for so:

Three aliens have invaded Earth, one that acts like a parasite by mutating humans. Another that takes in metal to give itself a form. Then there's the last one, that doesn't want to do anything to Earth. It's goal is lend humans the ability to fight back. Several cities now quarantined, this one girl now explores the world. Having not seen another human being in years. The Aliens that are assisting the humans are a race that look like mythological creatures, this was not their first time living on Earth.

Her name, is Necoretta (the names related to a Bubblegum brand) and her ally is a two headed dragon. The blade she holds is a sign of their contract, allowing her to gain the abilities she needs to survive.