Of course, you'd be interested in the Coffin of Andy and Leyley. I watched a let's play of the first two chapters last year and enjoyed the cocktail of awful emotions it inspired in me. Psychological horror is fun like that.
I think I kind of agree with you in that I am much more okay with incest ships for siblings who already have a fucked-up relationship in canon than ones with a wholesome relationship, though I don't think I could really say that I'm a fan of that sort of thing in either case (although I think it can be dramatically interesting sometimes).