Oh, I definitely think its Ellis.
This entire thing is a game to her and her father. It's back and forth, and for her, as long as he's in the picture, she will never have the power, nor the recognition that she deserves. She receives nothing but the bitter down falls that her father continuously throws upon her.
I think, this was her perfect oppurtunity to set Alex up and rid herself of her fathers burdens at the same time. As long as Alex is there, her and Frank would never have everything she desires for them. It was a perfect double hit.
Not sure how I feel about Jaime forgiving Rebecca like it's nothing. I mean, she cheated on you, with her ex-boyfriend that everyone thought she would marry, the night of her bachelorette party! I wonder if him knowing who it was would change his feelings any??? I think so ... and I'm sure we'll see that sometime.