Oh this is for the manifest destiny contest right? Which category will you be writing in? Sci-fi? If so, them that's really cool! My mind always draws a blank if I was asked to cook up ideas for a sci-fi story. Never had a true passion for the genre.
A few questions have sprung into my mind. Hehe, let's see if I can pry some information out of you.
To start of with something simple, what kind of powers does she have? Why does she have those powers? How did the government come to know that she had special powers?
I can imagine that if her powers were that powerful that the government would be use her as a living breathing atom bomb. If she is a child according to your description, I could imagine that she has a lot of pent-up emotional problems or trauma. Perhaps you could play with that.
the rebellion and planning
Why are the rebels fighting anyways? Is it because of a rising feeling of nationalism amongst the martians or is it due to other reasons. Most of the time most rebels actually hate each other. They are just like any political party. A lot of people bickering with many different viewpoints and personal goals. The only thing that keeps them together is their mutual hatred of the ruling government.
You can see this in many revolutions in the past. The most famous example might be the russian revolution where people had overthrown the czar. Amongst the group of rebels were not only communists, but also socialists, liberals, soldiers and even a few members of the nobility. After the czar was overthrown the different factions went on to kill each other in another civil war.
Oh I saw the word genocide pop into the title of your thread. If you want to have something more akin to a one-sided fight, you might want to look at the louisiana slave revolt. If you read into the records or the wikipedia article, you can get some really interesting ideas out of it. Atun-shei also has made a pretty good youtube video about it if you are not much of a reader. I do have to warn you that stuff gets pretty graphic; decapitated heads and stuff.
You said the background is a little complicated and that you planned to have it be around 15.000 words with four endings, so I have to give you a little warning beforehand.
15.000 words will probably not be enough to tell such a story well, especially with an elaborate background story and four endings. I came to find this out when I started to write my own stuff. Proper characterisation is hard to do with 15.000 words. It sounds like a lot, but you will notice that you quickly burn through it.
I suggest that you either make the scope smaller (instead of dealing with a full rebellion, make the story about a battle or a mission with the rebellion as a nice backdrop) or just plan to write a little more words or you have to rush some parts.
This is all what I have to say. I look forward to your story!