I'll admit, I'm really torn on this one. I can't quite decide which way to go. The thing is, I've been thinking about the characters so much that they're both--Theus and Theusa--now formed in my head. I know their motivations and their feelings, but I can only use one of them.
With Theus I gain the ability to have he, himself fight. I can show him with his family, which could really round out his character. Yet, I worry that he's too similar to other characters I've written. (Cett and Straff both come to mind from the Mistborn trilogy, though neither of them are as rounded, as well as Iadon from Elantris. I've done a lot of brutal rulers.)
With Thesua, I lose the two things I mentioned above. I couldn't soften her by showing a spouse and children, and while she'd still have a daughter, I don't see the child being as much of an influence on reader opinion. And, there would be less action in the book by a slight amount as Theusa will not be a warrior, and will have to rely on Jend to do her combat.
However, I gain a tad of originality. (How many tyrant grandmother city-state rulers are there in fiction? Have to be fewer than men like Theus.) I also gain some subtlety--Theusa's rule would be much more tenuous, because of her gender, and there would be a lot of politics working against her.
Both would play off of Yunmi very well, if for different reasons. Midius's interactions lean slightly toward me liking Theus, but not a huge amount.
I keep going back and forth on this one. So, I'll put off the decision until tomorrow and write a Yunmi chapter instead. Huzzah!