Marie is a free agent employed by a multinational mercenary company, looking for fortune in the Desputed Zone. She is a one-woman army, enhanced with cybernetic implants and granted autonomy by her employer - free to make alliances with any faction and complete her assignments at her own discretion.
She's capable of both great compassion, completing her missions without killing anybody, and great cruelty - leaving no soul behind. Different approaches yield favors from different employers, of course.
But there's more to her identity than just being a merc and half-machine. She spends her time off in solitude, drinking Earl Grey and taking care of her cactus collection.