It's always a crap shoot as to what to warn for in a fic. The obvious things, violence, sex, rape, etc., are the easy ones to put in. Who would have known that writing something about an anxiety disorder would set someone off.

Interesting thing about that, I have a hard time watching or reading about characters that are being manipulated or coerced into doing things they wouldn't normally do or be, much like people who are/were abused. There is this one SPN fanfic writer that wrote a story last year that I couldn't finish reading. She wrote two other fics that I absolutely adored, and are some of my favorites tomes, so I was so looking forward to reading this new story from her. As I was reading, Dean was put into a situation where he became unduly influenced and sank further and further into this cult like group. He became totally unDean like and John was fighting tooth and nail to get Dean out. But this group preyed on Dean's vulnerabilities and were able to influence and unknowingly coerce him into this group and become someone Dean would never have normally become. The further I read into the story, the harder it became for me reading Dean undergoing this brainwashing. I couldn't finish the story. Still curious how the story ended, I skipped several chapters where this brainwashing was the strongest and read to the end. I don't think I'll ever read that one again, it is just too hard for me and evokes childhood memories and feelings that I just prefer not to revisit.

So, you as a writer ask yourself, how in the world do you warn against something like that. Everybody else that read the story absolutely loved it, and there was probably no one else that experienced the same kind of visceral reaction that I did. So, you really can't warn against these kinds of things. So, you warn against the obvious and hope for the best with all other individual idiosyncrasies.