I think Sam's lack of privacy inside his own head is a worse violation of his autonomy than any bodily possession or physical assault he has experienced. So many supernatural beings have been inside his mind and know exactly what he thinks. Dean saw his heaven which was all positive memories that he kept to himself. People are constantly berating Sam for his own private thoughts and feelings, his anger, his desire for a normal life, the memories he cherishes. Both their enemies and Dean can't stop reminding Sam how horrible his inner thoughts are, that the mere feelings and ideas he holds inside are transgressions that need to be atoned for. Both the characters in-universe and the people in this fandom have decided thought crimes are absolutely real when it comes to Sam Winchester and they are punishable by death.
