Personally, I think Stewart is a potential manipulator. Being able to unmask him would be great, especially if we're following Vanessa and Iris' paths: just look at Iris's disastrous final appearance. Iris is looking for stability, but in fact, she's completely manipulated without her knowledge! Proof: she catches Blake with his sister at a nightclub. She's excited but envious of their relationship. It's a very interesting avenue to pursue because Blake is acting in a responsible and balanced manner at that moment.
If we choose a dominant path, it would be nice to see Blake emancipate herself: like: starting her own cleaning business, becoming a psychologist in her turn, becoming a nurse, being able to run the city, and also dominating her former dominants. Hedonism doesn't mean having no purpose or willpower. We're all broken in life by a series of events, but it's these trials that shape us and make us stronger! We also shouldn't fall into ridiculous caricatures and limit Blake to being a brainless idiot! Her adventures should allow her to rise above and assert herself. Seeing Blake, for example, gain the upper hand over Samantha, balancing her out, giving her back her taste for writing... would also be a great idea, rather than limiting a relationship to a chastity belt or a plug! Unless Blake can at some point impose a plug on her too ^^
You can be submissive or dominant without becoming a doormat or a trash can, especially when it comes to the hero of the story.