Goodnight, Irene. She was the first empress of the Byzantine empire when Charlemagne was coronated emperor of the Holy Roman Empire. Umm, she mutilated and murdered her own son to attain the position. And so closes the first volume of the Byzantine trilogy.
Charlemagne asked her to marry him. Didn't sound like such a bad idea to her, but her citizens flipped. She was overthrown, exiled and dead shortly after.