Oof. I don't even know where to start... there are so many layers to this book that I really did not expect. In some parts it was incredibly hard for me to read - that dread of somebody snaking themselves into your life and turning those you love into somebody you do not know and trust anymore. The despair in this book was tangible; it still weighs heavily in my heart, and I suspect it will continue to do so for long. I feel so much for Mary, this little girl who's had her world thrown upside down, who simply wants a better life - a moon to live on, where everything is okay - and doing every thing she can to get to that moon. We Have Always Lived in the Castle is filled with the desperate need of a child to hold on to a world she can cope with. This novel was so heartwrenching and tragic... I feel as though nothing I could say would accurately describe the pure pain in this novel. 
I'm going to need a long time to truly process this book I think, and I will probably find myself coming back to it again and again.