That movie scream racism and control... but a lot of it from personal experience. Both disability and having some interracial relationships in the past.
From the start you could see the family was going to be the issue. Example, mother seriously needs to cut the apron strings, she's just keeping Derrick tied down and isolated because she doesn't want to be alone. Her husband left her due time him. Like they said and she don't want the child she choose over husband to leave. She acts just like my dude mom has acted and has said the same things. She even guilt trips him whenever he tries to stand up to her. Brings up the time he was in the hospital for 5 months in a coma and having seizures, that she was there everyday and no one else.
The brother is super raciest as well. Saying Derrick doesn't like our gospel music, because of Anna. That he never cried like that in front is a white woman. Why does it matter if she's whites. Why not just say, I never cried like that in front of a woman in a professional setting? Everything was about black and white with him.
As far as, Anna I'm conflicted. It's hard to know exactly Derrick's mindset, but I do believe he's a grown man. Even if they act like his mentality is of that of a 12 month old. I do find it odd she knew so much about him and his life for her manipulating his hand and thoughts. Specially after Anna stopped coming around, he was showing signs of distress and self harm.
However, common sense like never bring up your sex life with anyone outside your lover and friend zone... never parents or in-laws. That's why I feel if she really was raping him she wouldn't bring it up.
I agree and believe people with special needs don't have low intelligence and that we can all learn to communicate. My son whose autistic show's me this everyday. He might not be verbal, but we find ways around to communicate. Be it pictures or sign language, that way he's not getting frustrated as easily and so he knows that he's not being isolated and not heard; and so he knows he has a voice.