Just because you put step in front of sis doesn’t make it ok. Cough cough porn cough

They're actually half siblings which makes it even worse

I forgot
It makes it wayyyyy worse
Cain needs some Jesus

No... they aren't half siblings.

Aria is the daughter of Countess Roscente (the prostitute) and an unnamed man (spoiler there)

Cain is the son of Count Roscente and the 1st countess Roscente.

Yeah, its creepy, but not nearly as creepy.