That will be my life; heiress

In one life, Navier and Sovieshu didn't have any children which led to Sovishu suspecting that Navier was infertile. Add the concubine named Rashta who was pregnant with a child beloved to be the Emperor's, and you have Sovieshu divorcing Navier to make his child "with" Rashta a legitimate heir.

But in this life, Navier and Sovieshu have a child.

Ethaniel Cassandra Vict is the only child of Emperor Sovieshu and Empress Navier of the Eastern Empire and thus the only heir to the Eastern Empire. Even if she is only female, she is her father's only legitimate child and thus his HEIR. And she isn't going to let a lowly concubine take that away from her no matter what.

"The throne rightfully belongs to me, for my mother is the Empress. It doesn't matter if your child might be a son, he will only be a bastard baby. And thus have no claim to the throne over a LEGITIMATE heir, even if I am a woman,"