The Strange Case of the Alter-Ego

A superjekyllock (is that a thing? It's now a thing) fanfic. Sherlock call the Winchesters for a case involving a man who suffers from black-outs. DID, an alternate persona, right? Easy, except for the fact that his 'alternate persona' has jet black eyes and superhuman strength and speed. (Please review! :D If you haven't watched Jekyll, you should! Highly recommend!)