Sorry, this is again very long, I am going to let go the exchange, I feel it is not a matter of "I am right" "you are right", we just both have given some input, which may or not be useful.
No, that's not what makes it boring: it's boring because it wouldn't fit the story, imho. See, you can have blackmail by threats of violence, but those only make sense for a character who is prone to violence, for example a bully. [...]
But Marc isn't violent against Katherine, [...]
I see the point your trying to make, but IMHO you are already trying to get a full path for Marc, which has not yet been done in the game, thus I disagree on the "not fitting the story", the story has still many possible paths to take.
And you are explicitly assuming that when I talk about blackmailing, I am talking about physical violence, plus assuming the fact we have not yet seen Marc e.g. slapping Katherine, does not mean he could not get (or better, threaten to get) as aggressive with her as he is already with Myriam.
For the second part (physical violence), even just the threat of Marc trying to involve Katherine into his sexual escapades, even just as "partner in crime" (effectively, the possibility you were saying you would like to see), for someone who is protective of Katherine and her somehow innocence (does not mean naivete), as Myriam indicated e.g. in the dialogue at the school, would be already a threat to the personal integrity of Katherine, without implying physical violence.
Effectively, if people want to blackmail person "a", the may threaten to physically damage person "b", but a threat can be not a purely physical one, but a physical one which may not immediately looks as a threat, but effectively end up affecting "b" also psychologically.
Without getting too serious (but we are already kind of serious
)...
Someone (let's say "manipulator") to attack psychologically and push person "a" to do something they want "a" to do, can behave in an apparently friendly with person "b" to try to get in their good side, while effectively involving person "b" in something that can have repercussion and/or trying to get them in sexual situation, but with the intent of then damaging them emotionally, socially etc.
Of course it requires person "a" to care about person "b", with an emotional and/or ethical component (a e.g. purely contractual one is not sufficient, becauses misses the most effective part) - but emotional and/or ethical, does not mean forcibly romantic interest, even e.g. mother-daughter ;-) relation without any "extra" could be more than sufficient.
Of course works better if "manipulator" can count on others to support him, so that even if person "a" was to try warning person "b", those people could help play down the warning.
Is not by chance that a characteristic of some type of sociopath is that they try to create and show themselves has having big groups around (e.g. nowadays, thousands of people on Facebook), it is not only to satisfy their need to feel at the center of attention, but also to leverage the fact many will assume that one with such a big (apparent, at least) group, some of whom explicitly saying he is nice, cannot be behaving so badly. They have no depth of feeling (aside thing like their ego) and no real sympathy, and even their empathy is limited, however they often develop the capacity to pretend sympathy and feelings.
There are ways in which they can kind of give themselves away, be seen for what they are, but it depends a lot from how other people are and behave and communicate between themselves (not entering in details here), so even if someone, like person "a" in our example, can see them for what they are, they can be presented as one vs the many around manipulator and the manipulator himself.
For the first part (your assumption Marc has no violent tendency), it all depends how he develops.
Remember Marc has already shown he can be going down the road of his father, who can be not just kinky rough, but rough violent with Myriam, e.g. by grabbing Myriam and basically forcing a deep throat, and slapping her. Therefore, assuming Marc cannot be violent in a sexual way, is already contradicted in part.
Of course, that does not automatically mean he will go in that way, that depends from two factors: 1) what Zorlun has already foreseen to put in the future episodes as paths; 2) how the player makes the Myriam interact with the various characters (thus also the characters with her) and with Marc (including, if not kicked out and not coming back, Anthony).
If you play in a certain way, Myriam is not submissive towards Marc (or Anthony, if still around) in a "kinky submissive but really equal", but is really submissive, and that submisiveness towards them can grow (though also interplaying with other factors that can limit it, like the values for willpower and dominance).
And Marc can e.g. stay that way, or get rougher, and e.g. slap her harder (don't forget some scene with Anthony could increase the "pain" value, it could be that even Marc at some point get that possibility).
About Katherine, if he is aggressive and rough with Myriam, having shown already verbal aggressiveness toward Katherine, he would not be impossible he shows also the same towards Katherine, when she tries to block his attempts with Myriam, though at the same time Zorlun has already excluded anything sexual between him and Katherine.
Also, the intent of blackmail is forcing a woman to do something against her will; if there are other means of achieving this, and Marcs "skill" is one of these, then blackmail is just weak and unnecessary. You don't need to threaten Myriam with Katherines well being if it's enough to tell her what to do.
Not said. It is not a business criminal transaction or a normal business transaction. It depends from the psychological profile thought for Marc.
For people with a certain type of mental profile, it is not only about the result, it is about the feeling of control over the others.
That's good, yes, but it has its limits. There is a reason why even games with dozens of developers and millions of dollars don't have complex branching paths and broad storylines. Complexity grows exponentially and at some point Zorlun must cut off some ideas, some content and some "But why not have both in it" pleas, because otherwise his story would come to a halt.
Agree that there are limits, though you are forgetting the reason a lot of big budget games do not branch like that, is also because they need to spend huge resource in real-time interactive graphic generation and development, put sound and graphic artists etc..
While the graphic results Zorlun has reached are good, and despite its limitations, bugs and some odd things, Daz Studio is already quite good and powerful (well, although thanks to the rendering being external, and putting aside the video part generation), reaching the graphic interactive quality of some commercial games nowadays takes a lot of resources, big teams, money etc.
And that's why I'm voicing my support for the "dominant Marc" path because I like where it is going (at the moment), I like the story so far and I hope it will be developed further.
Actually, I am not at all against the dominant Marc, till now I have a played in that direction, even if I may see other paths, and may evolve differently in future.
At the very least, given the premises till know, I see him trying to go in that direction following the footsteps of Anthony, and therefore having to see how Myriam will act, react and manage about that tendency.