Brencis doesn't rule alone. I don't know if all vrakhiri do the same, but in Vale Sangora they've formed a court, consisting of the knyaz and his three boyars: Bakir, Ambrus and Xanthe. Not all three of them were sired by Brencis, but they all obey him. Could they stand up to him? Could they kill him? Could he kill them? I have no idea, but they clearly share some sort of a bond.
Vrakhiri Court
Legends