Her brother’s dad is the emperor and her dad is another man
He’s illegitimate because of his mother’s status
The marquis was poisoned after she had his child, making her the one with sole power over the estate. She then seduced the emperor and bore him a son, which gave the emperor the excuse he needed to murder his sons born of his wife, the empress. He can't make a legitimized bastard his heir off the bat so as it stands, one of the royal dukes are also in line for the throne without the prince doing something of significant notice. He could also kill the competition but everyone is rightfully on guard after killing the empress's friends and family.
tysm!! It makes more sense now
can anyone explain to me the family because if she has a brother why she heir apparent and not in line for the throne compared to her brother who isn't an heir but is part of the royal family I know they have different fathers and the marquis would give his wife to the emperor? But the whole family thing is so confusing to me.