It's a well-known fact that a villain could do the most vile s h i t possible, and as long as they're even mildly attractive, there are going to be people lusting after them.Literally just imagine him but instead ofa white haired anime boy, he's an ugly, aging senile old man, and I wonder if people would still 'uwu' over him
I guess everyone wants to be that "special" one that "fixed him" and got all the attention and dedication
But as you said, the problem with Luceris is that he's treated inconsistently. The story markets itself as a revenge story, and a revenge story hinges upon having a hateable antagonist. It's one of those genres where it's arguably detrimental to make them too sympathetic, or sympathetic at all. It seems like the author started with the intention of writing Luceris as a monster, but then got carried away by their (and their fans') fantasies, and so his character became progressively more UwU-fied. I'll go as far as to say that this is one of the downsides of interacting with your fanbase too much during development: you might lose sight of the original vision and just... roll with whatever seems to be fun at the moment.
For the sake of the story, it really would've been better to make Luceris old and ugly. The amount of hate would've been something to behold. (or just, y'know, have the MC there as a prisoner w/o the marriage subplot that doesn't even feel necessary for anything beyond ~drama~)
Let the hate flooow~There's just something about hating on games like this which is so liberating.
(probably because there are few places where you can express an honest opinion without being unalived for it bc it's mean to the authors or smth)