I stood there silently, looking deep into the eyes of each and every one of them. I wouldn't leave until I had what I wanted.
"Well?" I asked, growing impatient. "Do we have a deal?"
One stallion stepped out of the shadows, "Oh, we have a deal all right." he stated.
I grinned at him.
"But," he added, "Only because we know what you are."
"Oh?" I asked, my grin turning to a smirk. "What am I?"
He looked at me coldly.
"Poison."

The following description is guaranteed to at least a little change with time. I'm kinda writing the story as I go. But here's a basic description to go by.

Poison is a young mare who, because of trials as a foal, has become an assassin unmatched in skill. She was born into the badlands outside of Equestria's harmonic reach, and into an evil monarchy government.

The evil dictator running it all is known for taking every precaution against all threats. Those who escape his wrath are few, those who escape his kingdom are fewer.

And those who survive opposing him are almost non-existent.

The experiences and horrors she endured after being taken from her home have taught Poison one thing; never give up. She was originally taken as another foal he could use in his ever powerful army. But ever since she escaped, every waking moment is spent seeking out ponies within the monarchy to take down.

One day, she discovers he has plans for their neighboring country of Equestria. Plans that include releasing every demon in Tartarus upon them, leaving him to rule over the remains. With the danger of this new threat, as well as the fact that Equestria is completely unaware, Poison makes the decision that it's finally time to join forces with the resistance.

She offers her services, which they gladly accept thanks to her reputation. She is given a team of elite fighters and spy's who, combined with her skills in assassination and keeping undetected, make an invincible force. They will be the key in taking down the monarchy, and keeping the demons in Tartarus where they belong.

Poison, along with her new team, strive to end the evil monarchy once and for all.

Nothing will stand in the way of her completing her mission.

Even if it kills her.

(I'll probably include the CMC in here somewhere because it AU. Not quite sure where yet.)