And honestly I find Alexia a really weird deuteragonist. I mean, she is really just there for the porn. Rowan has agency and his choices matter. Alexia's choices mostly decide if she will have or see sex.
In the future, it may play a major role if Alexia goes full Melkor Mode *i mean* Full NTR Corruption Path in Act I, think about this carefully, being the players so rewarded with all those sex scenes with nearly every creature alive in the Castle (because there's not necrophilia ;v ) by Alexia can have it's consequences when Rowan may be in need of her help or support on the next Acts, it doesn't mean that she in the future will still relying on Rowan but of her own to reach her selfish goals.
Regarding Rowan's agency, he have the "freedom" The Twins provide him, but failing them it's an instant Game Over, another thing is about the importance of his choices, think carefully, none of the ppl who works in Bloodmeen in charge of a particular area of significance have been chosen specifically by Rowan, nor less Rowan can (nor even tried to) organize them to work with more efficiency, but by The Twins and they give them agency enough to work as they wanted (it's not surprise that even if you have the resources you can only build just once at a time, the same can be said of the library with the abundance of investigators), and if by any means he doesn't reach the goal planned by The Twins is Rowan the only one who pay the consequences...
Something like that was revealed by @Rein when he reminds us that Rowan's decisions impact in the character and over other under his wing, the choices taken by Rowan only matters if are aligned of Twins desires, an example clear of that is Rastedel's Fate. Personally, Rowan in Act I is more close to John Dagget of TDKR believing having power or influence as much he gives on himself for the cause that's not of his own, Rastedel must serve as a lesson for the character that will impact seriously in how Rowan acts, think and hopes for anyone in Bloodmeen, specially for The Twins.
So in resume, i only expect that going an Alexia full corrupted makes of her a less cooperative character, making hard for Rowan to succeed or even competed with Alexia for Power over Bloodmeen.
first time I sent Alexia out to work, I started her with the Library. And unlike every other path, the Library clearly tells the player that Alexia has the potential to have agency (because she has power, enough to intrigue probably the most powerful person in the castle at least before Tharos shows up). So after that the fact that in every other route she is a victim or a voyeur is weird to me.
Well, think in Alexia's circumstances... She's a peasant, and as many of the people of the Third State in a Feudalism Bullshit Society is probably she lacked of any formal education, if it wasn't of her kidnapping by The Twins and the curiosity of Chliona, she could have lived a peaceful life until an elder age and died without knowing nor even a single prove or suspicious of her affinity to magic, so, it's not weird, it's her unfortunate reality she had to live and she's like every other person...
But her role may amplify in the future, it wasn't promised but there's a hype for what's called as "Magical Alexia".
That's because Alexia is weak and doesn't seem to be crafty to scheme behind the scenes.
Perhaps you didn't reach enough corruption into Alexia, she step in front of an orc for called her slut, she in a sense, make use of Andras to give that orc a lesson, and when the orc finally ask for forgiving, she can still manipulate the poor wounded orc to seek Andras again (knowing how Andras just nearly kill him and a second confront would be his death), that's just how manipulative and scheming behind the scenes she can be and will be in the future...