About TitS' incest subplot, is it really that offensive?
Yes. Not because "icky incest ew", but because it's purely fetishistic. In a way it reminds me of all those scenes/shots that Tarantino sticks in his films that become universally awful in retrospect once you learn about his foot fetish. In Trails' case, the distinction of the fact that they're literal adopted siblings serves no other purpose than to indulge the creepy sexual fantasies of a specific type of creator/player.
Cold Steel, aside from more incest, also has other stuff like this in the form of weird ass head petting. To give one (of many) example(s), I played through a scene recently where you meet a character's father, and when you think they're going for a hug, the father's character model pretzels its body so that he's holding his teenage daughter with one hand and
petting her on the fucking head with the other. The scene is contorting itself in an unnatural way in order to line up with the bizarre and unrealistic conceptions of human interaction held by your average weeb fuckface.
The scene, rather than simply being a normal emotional moment where a father hugs his daughter, becomes this sort of fucked up, weird, and laughable display of relationship power politicking so that the writers don't have their beady eyed player base getting emasculated at the thought of a man that's not their self-insert protagonist fully embracing their waifu.
The same thing applies to Estelle and Joshua: Instead of the actual thrust of the relationship (friendship blossoming into love) taking precedence, it instead becomes secondary to the theme of "fuck me hard, onii-chan", because that's what gets the weebs hot, sweaty, and invested. They're not legitimately attempting to portray incest, they're just pandering, and it brings down the quality of their work. They're essentially putting
this in the middle of an otherwise perfectly good story.
