Yes, I've been thinking about this as well. While subduing Lena's will might be a turn-on for him on its own, I don't think he showed all of his cards yet. I very much suspect he intends to use Lena to safeguard his future business deals as well. It was already hinted at when he worked with Agnes and how fast he switched faces from being an attentive authority figure (that a type of Lena was enjoying) to a desperate manipulator who wants to please Agnes and their business arrangement showing no regard for Lena's comfort as his model whatsoever. Perhaps knowing that she works in the cafe he intends to acquire, performs with a pesky activist who tries to undermine his goals and knowing that very few men would resist her charms (thus, the constant theme of their shoots being about her role as a seductress and an object of men's desire) made him realize her potential as his negotiations tactics first and foremost, both for business deals and damage control (get Emma out of the picture). He can't outright tell her that and offer becoming his dark Padawan, otherwise she'll realize all this power that she has and he won't be able to control her. That's why I think he put that clause about proactivity and didn't set any limits to sexual contact in his contract aside from Lena's consent. Doing an underhanded "photo shoot" while his competitors fuck Lena will give him an ultimate edge with so much compromising evidence against them and none of his involvement (Lena wouldn't want to out herself like this and become a complicit in his illegal actions).
P.S. it's entirely my speculation based on the facts presented in this game. If things play out exactly the same way, then it will be pure coincidence and a huge success of my detective work.
Ok, I really like the idea of Lena becoming Seymour's sexy spy, seducing and then blackmailing business partners and sabotaging businesses to fail so he can buy them.
But, sorry there is always a but, it doesn't really make much sense. For the cafe to fail all Lena has to do is stop helping them. But either they are already failing because Lena didn't help them or Lena really cares about the van Dykes. This is not Star Wars where decent people become youngling murdering psychopaths in a blink of an eye. And to sabotage them she wouldn't have to do some sexy evil stuff, all she had to do is stop helping them. Which is not very exciting.
Spying on Emma would make sense in a way but there is no need for sexy stuff, all Lena would have to do is to pretend to be her friend. Again, not very interesting. Also I don't get the feeling Seymour is that concerned about Emma.
Seymour whoring out Lena to a business partner can easily happen but the problem with that is that you need new characters for that. So this would be more a one off thing, like with Ryan in GGGB.
I also don't get that Seymour is desperate to please Agnes, he seems quite eager himself. And the clause about him not being allowed to touch Lena except she asks for it, well, maybe he just wants to make her beg
So, while I think you are mostly right in that these things will happen, I don't expect it to be that hot and exciting. My theory for Seymour is that he is trying to break in Lena, to make her willingly accept to be his playting/whore/slave. Axel knows (and is likely helping) and that is why he was so calm to Lena after they posed together and why he isn't obsessed with Lena any more.
Talking about detective work, you have any idea when we will find out what is the whole ruckus about Stan?