I could have sworn that it was eluded to that the brother and sister have sex regularly. Sure, he forced himself on her. If I remember, the mom made him do it, too. But, like I say, I could have sworn it was mentioned somewhere. That would make it NTR, wouldn't it?
While it is true that Claire had been repeatedly sexually used/abused by her brother William, it wasn't willingly done by Claire... it was expected of her by her mother, as her mother had been using her son to get back at Claire for what she believed was the failure of her marriage to both William and Claire's father (Bill).
William viewed himself as 'Head of the Family' by right after his father's death and also from the way that his mother was treating him (even sexually); which, in his mind, meant that Claire was his property to have and use (like how we believed his father treated Claire)... though he had to go along with his mother's plan for entrapping the Antichrist (you, the player), he still very much felt that Claire was HIS and was jealous of the fact that his uncle got to touch what was his... and also very upset by the lengths that Claire went to in order to get her Uncle's attention, as well as suspecting that Claire liked her uncle more than just as and for her mother's plan.
If Claire actually was romantically interested in her brother and was in a true relationship with him, feeling the same things towards him as him, then yes, it would've been NTR... however, Claire was in an abusive family dynamic, where she didn't have a choice of what was being done to her... hated it and felt powerless in it... so there is no reciprocation of William's 'love' from her to make it NTR.
Claire is a victim and rape survivor.
