***SPOILER***
I have a feeling he knew he wasn't related to her? But all that being said, we can't expect many morals from a PWP.
Yes, it’s very likely so
That would so explain why he hasn’t helped her out “the slums”
Yup, he and her mother, both of them having a different reason, tho mother want to humiliate and break her, bastian didn't want her to leave to the monastery and lusting over her.
NOT A SPOILER, just my personal opinion..
I think it was Bastian who put the curse on her.. And I think the reason is due to this bizarre desire he feels towards her and therefore it is a sick attempt to get closer to her and possess her no longer in the brother sister relationship..