I think that the word that best describes Sherlock is interesting, considering the fact that he keeps severed body parts in the refrigerator. He is interesting because, no one knows what is going on in his head. No one can read him, but watch out, because he can read you!
Sociopath, he has described himself that way. But, I know most people are going to say that is not a describing word and it isn't. Unless tu think about it like it's a mental state making a description. He hasn't just dicho it either the internet has if tu look up the word sociopath his picture is first. I rest my case