We had something like this happen last night, and I was completely taken off-guard, since for the last couple of years, I can reason DS through such things, as long as he's healthy and not in some crisis mode from something.
DS9's wrestling coach was giving the kids their end of year trophies, and made a speech about each kid as he presented them. When DS9 came up, he said that DS was "like Dr. Jekyll and Mr. Hyde" -- he's the kid who reads all the time and wins the spelling bee, but he's ferocious on the mat.
Afterwards, DS9 asked me (not surprisingly) if he could read Dr. Jekyll and Mr. Hyde. I told him I hadn't read it myself, but I would think it might be a bit scarier than he would like. He asked me to explain, and I told him it had murders in it. He told me that he's read other books with murders (e.g., Harry Potter, LoTR, Agatha Christie) and hasn't been scared. I told him I thought this might be different, but I could check it out. He asked for a synopsis and I told him my recollection of the storyline albeit from the old movie -- Dr. Jekyll is a good person and a scientist. He takes some kind of potion/drug that he's concocted and unexpectedly turns into a monstrous man that they call Mr. Hyde. In response to further inquiries from DS9 asking what makes it scary and what kind of monster Mr. Hyde is, I explained that I believe Mr. Hyde kills people. DS9 lost it saying how could coach compare him to that.
I explained that the term "Dr. Jekyll and Mr. Hyde" is commonly used to refer to people who have unexpected combinations of traits. The coach was trying to say that while many people may stereotype kids who like to read and learn as mild-mannered, anyone who thinks they'll have an easy time wrestling DS9 because he's "the kid with his nose in a book all the time" will be in for a huge surprise, because DS9 is a fierce competitor. I explained that the coach sincerely meant it as a compliment. DS9 couldn't stop crying, and had a horrible time getting to sleep. He said he never wants to read the book, not because of the murders, but because a good person turns into someone so bad, and someone had compared him to that.
