I'm curious where you aim at with the content for Marc: after the pool scene, he pretty much lost all progress and confidence he built up and turned into a snivelling, self pitying, insecure, passive kid. It's almost as if "sub Marc" is canon and "dom Marc" never existed.
For me, the appeal of the story of Marc was that he was her son who dominated her and got "better" at it - not necessarily in the right, responsible direction, but maybe with a selfish, abusive attitude.
At the moment, he is just a boring little boy.
So long story short, will Marc become more of his old, dominant self and will the story arc with him contain some elements that made this path unique (incest with dominant son)? Or will Marc be stuck in the cliche of the insecure kid who never saw a woman before?