Maybe the fault is all mine for thinking that a game which began with choices to shape your character's past and personality would actually let you choose your character's personality type. I do have a tendency to jump to wild conclusions like that.
Yes, Edwin is
always a sadist.
That's core to his character and has never been a flexible quality. And I don't think it's all that surprising that the Kathy path, where you seek out her mentorship, involves her stoking Edwin's sadism. That's kind of her thing. I mean the (optional) scene where she gives Edwin his "homework" is him seeking her perspective on the topic. I mean... 1 + 1 = 2, you know?
As for the Vicky video thing, pretty much what has been pointed out: you've misinterpreted the text. "(Now... empty the trash can.)"
is Edwin emptying the trash can. I can see thinking it sounds like he's dragging his feet, but it's just him confirming the finality of his action to himself and the reader.
Edited to add: I will admit the Marlow thing is pretty hackneyed. It's hinted at very early in the story, but it's never used to inform Edwin's perspective when it comes to Mina, the threesome with Rosalind, etc when it very well should considering how formative it would be. My hand wave would be Edwin is pretty good at compartmentalizing and has moved past it, but it's honestly just me not factoring it appropriately into the story.
Likewise, while it's disappointing that our treatment of Killian has so little impact on his ability to process the information right now, I can see that being more of a long term struggle for him - that splinter in his mind that he can only fight effectively if the MC has taught him some introspection. I'm willing to see where this goes before passing judgement.
It will have a
major influence on how he reacts to the information. It's not reflected in that scene because, in part, it's a prime example of the boy's old dynamic. Edwin is pushing his narrative hard, forcing him to accept it, and Ian goes along with it as a follower. At least was my thinking, beyond my tendency to save "more" for later so you can't just easily back out of your choice of telling him if you don't like his take on the matter.