Sister of Revolutions and Lies

Britannia was a kingdom where the strong thrived, where the strong ruled. It's something the Britannia children knew well, after all if you were the emperor's child. You had to be strong, smart, or both in order to survive. This was something the Vi Britannia siblings lurked quickly. For at the age of ten and eight. When the twins, Artemisia and Lelouch, and their younger sister, Nanally, watched their mother dye.
It was mere days later, when Lelouch approach their father. Demanding his visit his little sister, who was no longer of use to the emperor. So she, and Lelouch were exiled. Separating one Artemisia from the two people she loved and cared for more than anything in this world. Leaving her alone, as her father's favorite child. To claw her way to become the best, the perfect daughter to survive, and she did just that. She became the perfect princess.
Yet what happens when slowly her mask starts to break, her heart starts to yearn for what is lost. What happens, when the Sister of Revolution and Lies finally reunites with her brother. Yet here they stood, on opposite sides of a war, will he deflect, or will she? Or, will neither falter, will they fight till the other is dead? Or will they have mercy upon one another.