She became a knight for being pretty much the very first pilot of a real knightmare frame, the Ganymede. And she was so damn skilled with that crappy machine (she got nicknamed, Marianne the Lighting after all) that even the emperor himself was impressed. That’s why she, a mere commoner, could marry the Emperor himself. So sorry to spoil it on you ppl, but the fact that she was a knight was already a known fact.
(no subject)