I hope he has some genuine depth to him - most importantly, the ability to actually grow in some way over the course of the story, maybe due to the influence of Lena or Ian (or both) if they manage to get very close to him.
I doubt he has any incentive to do so. He owns everything, he believes himself to be the free person who can shape reality around him to his will. It's not like he's missing love or affection or some example of goodwill, so there's nothing Ian and Lena or anyone else can show him that would change his ways. Frankly, I think it's too late for him to change, and he chose the hill to die on.
The only plausible way I can see for him to "grow" is if he actually underestimates his desire for Lena and falls for her. Just like he wants to make Lena depend on him, he might become dependent on HER if he really thinks her to be the rare diamond that he seeks. And that might open the window for Lena to manipulate his desire to her advantage, because behind his bold speeches, he's just a man with predictable desires. But it would be at the cost of always giving him something that he wants. If she becomes more trouble than she's worth, he'll lose his interest and get rid of her (and probably make her life very miserable).
Ethan in GGGB had very clear desires and Ash could only influence whether he was still dating her mom or dumped her. Based on that, I wouldn't expect a player agency to affect Seymour's growth in any way, only whether he has admiration for either of the protagonists (if Lena/Ian join his side or just follow their own goals without getting in his way) and whether or not they'll be able to stop his plans. I can only see his growth after he realizes that he was outplayed by some youngsters.
then you already lost before even starting out. You lost on variety, on fun\hotness, on quality. It's a fact. Let's hope Eva is smarter than that, but I must admit I have my doubts (IIRC she modified the game because someone complained a few times in the past).
