SPOILERS
Yeah, but Mars is weakening. He is showing weakness more and more often. That conversation with Vi was too much in the open. Cecille has no weak points. She doesn't love anyone, she has only her pride, and her pride and ego are becoming more and more twisted thanks to Mars. She is a clock bomb.
Mars wasn't even able to make her lift the paralysis spell despite trying many times. Cecille obeys Mars because she enjoys it. When she doesn't, she doesn't care about his orders, even if she still didn't notice.
And the compatibility between Mars and Cecille seems bad for him in my opinion. Cecille feeds on him, she would do it even without any curse, and he just gets weaker. Because she loves where she is going but he hates his path.
Also, the confrontation with Elena was demolishing for Mars. At some point he had to retreat and I even thought that maybe he wouldn't be able to completely break her. And maybe that was the case, I am not sure how strong is Mars' control over Elena.
There are SO MANY possible bad endings for Mars... so many ways his entire house of cards could go down... which makes the story SO interesting...