I see Seymour like a old and rich Axel. He's a capitalist pig and he's used always get what he wants when he wants. And now, he wants Lena be his submissive slave doll, making she have no other options of work besides photoshoots with him, corrupting her in this photoshoots and buy her with expensive lingeries and jewels. I'm playing around looking for what might happen if Lena, in one of those photo shoots, refused Seymour when he attacked her more directly. Maybe he finds out about Ian and Lena's sexual/romantic relationship and thinks that to have Lena for him he's going to need to destroy and take Ian away from her? Or convince, use or manipulate Ian for he (Ian) convince Lena to make what Seymour wants?
Yeah. I suspect that Seymour also sees Axel as a younger version of himself, and that's one of the reasons he's working with him. They're proving to have a similar taste in women too…
I think there will be a few different scenarios for Lena and Seymour. A Nietzsche-loving Lena with high wits and charisma may turn out to be Seymour's equal, in his own eyes as well. Or she could have a far more submissive role, as you mention. When Lena talks about her secret kinks, the "to be dominated" / "being a sex slave" options (I think the wording may have been changed at some point?) are only available if she's involved with Seymour, if I recall correctly.
The scenario I'm most unsure about how will play out, is if Lena rejects Seymour's advances. It wouldn't make sense if he just backed off and accepted it, but there's limits to how dark the story is likely to turn out. Logically she would be most (financially) dependent on him if she's not on Stalkfap or doing nude modelling, but I assume there'll also be a way to avoid him if you're actually trying to play a more modest version of Lena.
I'm also unsure if Seymour will respect Ian more if he's confident and more similar to him, or if he'll see that as a reason to destroy him because he stands in his way to get to Lena. He could easily make him lose his job, and he probably has some shady dealings going on with Perry's dad the Mayor as well. So maybe he could even use his power to kick him out of his apartment. At least he's guaranteed to use that power to try to force him to stay away from Lena in some scenarios. Either way I'm looking forward to sending Ian on a kamikaze mission to take down both Axel and Seymour – regardless of whether it succeeds or not.