She does. She has a spell for everything because she has terrifying patrons from another planet.
Carissa is scared, but she's decided that doesn't make a lot of sense. Mhalir has really low expectations because his slave has been his enemy who hates him for the last several decades. Even if she is really really defiant sometimes she is going to be better at this than Alloran. And Mhalir - isn't Asmodean, though maybe he will be when he's had time to think about it, and while he's not he has his weird alien opinions about things instead which seem to include that it's entertaining if your slaves are opinionated. With that set aside a lot of her feelings just amount to - wishing she was safe, and she can't be, and this is probably safer than not-this, because the more useful she is the more lengths he'll go to if anything happens. (He might have her raised if she died? It feels arrogant and ridiculous to hope for this, but, like, there is an important way in which 'slave' is not an accurate gloss which is that she is actually quite valuable to him.)
And then there's the thing where she feels disloyal and confused all the time, which she doesn't really want anyone to see but - if he decides to be Asmodean he can probably help her with it, and if he doesn't he won't regard it as an important failing, so - it seems worth a try.
Also she totally thought he had a Yeerk in her secretly anyway so it's kind of nice of him that he didn't.