John has been kidnapped by someone or other (could be Moriarty) who is obsessed with his looks. Rapes/abuses him and says the words "Purple is such a pretty color on you" - this is his reason for beating him.

John is rescued after a week or so by either Lestrade, Mycroft or Sherlock (or all!) and much comforting ensues.

I'd prefer if some permanent damage occurs - either from the multiple rapes or something else that the madman does.

{Mycroft says 'dream big' - well, I'm dreaming big things of this prompt being filled!)