Its funny because part of me thinks that they rushed the reveal of Theo's intent to Gordon too quickly, and put them on opposite sides too quickly, but I assume that Gordon is going to be under constant threat and he and his chief are going to end up on opposite sides of the moral equation.
the actress playing Theo's system is doing an exceptional job. While I think its a stretch, I look at her and Barbara as the opposite halves of a twisted yin and yang symbol
Barbara is the irrational dark half that just wants to be chaos personified, she's clearly insane and wants to lash out at everything that she feels has wronged her no matter what the cost. With Theo's sister, she's the white side of insanity, we know she's crazy but she is more rational, she sees her actions as both rational and planned, and at the same time it brings her intense pleasure in everything that they do.
When you combine her and Barbara you get one full on complete psycho circle where everything is planned, and there's a end game to everything, but at the same time both have a simple end goal in terms of gaining pleasure from the action.
I don't know if the appearance differences was intentional in casting, but everything, the way they both dress, skin color mannerisms leads to that whole circle of crazy.
One won't be able to succeed without the other.