Read it free here: http://www.tor.com/stories/2012/11/the-queens-army
Title: The Queen's Army
Author: Marissa Meyer
Year Published: 2012
Synopsis: It is time. The boy must leave his family to serve in the Queen’s army. To be chosen is an honor. To decline is impossible. The boy is modified. He is trained for several years, and learns to fight to the death. He proves to the Queen -- and to himself -- that he is capable of evil. He is just the kind of soldier the Queen wants: the alpha of his pack.
I'm so glad that I read this before I read Scarlet. It was really nice to find out about some of the characters in Scarlet before they make an appearance, and to find out why they act the way they do. Plus, it's also a little bit of a continuation from Cinder - we know Levena is up to something and is creating an army of genetically modified soldiers, but we have no idea why or what they are.
I really loved seeing the way Ze'ev interacted with his "pack" and how he develops over the course of the story. He's smarter than he pretends to be, and a better fighter than he lets on, but he doesn't want to be the Alpha. I think it's fairly important to learn about Z before we see him in Scarlet, because it certainly helps explain a little bit about his mentally and why he does the things he does.
Marissa Meyers' short stories do not disappoint, and I would strongly recommend this to fans of her Lunar Chronicles series. Especially if you haven't read Scarlet yet! And even if you have, I think this is still an excellent read and will really open your eyes a little bit more. 5/5, and I hope there are more short stories to go along with Cress and Winter!