The Carer, the Caretaker, the Sociopath, and the Hero (WhoLock Fanfiction)

(Based in the YouTube video created by Whovian Sherlocked) The 12th Doctor and Clara travel back to London to find a powerful weapon called The Key. Meanwhile Mycroft gets wind of this key and hires Sherlock Holmes to find it before the Doctor or any other enemy can get to it. The Doctor obviously wanting to make sure no one can get their hands on this powerful weapon goes head to head with Sherlock, who is only very interested in this certain case. Two brilliant men fighting on opposing sides with their loyal and clever sidekicks is enough to take down the Earth, maybe once and for all.