Actually I think you might have things flipped. Jezera is just as much a childish brat as her brother, only with a cerebral nature as opposed to Andras' more brutish nature. While I don't believe either twin should die until the very end, as even killing one would remove two of the major elements of Rowan and Alexia's potential corruption storylines, Jezera seems the more expendable one to me. Andras is more than just the muscle. Jezera has virtually no leadership abilities while Andras does have that capability. If Andras died leaving Rowan with whatever forces he had amassed it would be over far quicker in his favor than it would be if Andras were alive. Take Andras out and Rowan would have the Twin's military forces on his side before Jezera was even aware they were turning against her.
You could put Jezera and Rowan with perfectly equal forces against each other and Jezera would lose every single time as she's used to hiding behind her brother and working things from the shadows. One thing that's easy to miss is that Rowan is presented as the perfect package when it comes to his abilities as a general. He's an extremely capable fighter, a brilliant strategist, a master of tactical warfare, and an inspiring leader. The twins specifically sought him out because he's probably the only person in all of the kingdoms that can do everything the twins need; which is to say that the twins would need multiple people to fulfill his role. If they were all put on a level playing field it would be Jezera out first because her troops would be disorganized and would easily fall of their more savage impulses because she wouldn't know how to handle them. Andras would fall second because he at least knows how to keep his troops under control and he knows how to lead. Andras only lets the player think he's nothing more than a savage brute, but at the end of the day he'd be leading the troops into combat without Rowan.
