I agree. I think Rachel Harris is playing the part so well. She could go so over the top as THE.DEVIL'S.THERAPIST. But she doesn't, she has a patient that happens to be The Devil. (I don't think I'd miss Ella though, and I wouldn't mind if they wrapped up Mother's storyline so we'd see her a bit less either.)
I like Trixie as well. I'm calling it now (I'll be wrong): Trixie will be able to bring the sword to full flame. She's the product of a being with God's Blessing. There has to be something that rides along with that.
I'd typed out my comment above (about Mother) before fully reading your comment, so: SNAP!