Pawn Takes King (слэш)

John Watson had always assumed that he would never play a major role in Moriarty's game. After all, Moriarty was always too concerned with Mycroft and Sherlock Holmes to pay an invalided army doctor any mind. So he is taken by surprise when Moriarty makes a rather shocking demand: one month with John Watson in exchange for Britain's tactical positions and plans in Afghanistan. John has now become a pawn - to be used as both Moriarty and Mycroft please. But what everyone tends to forget is that a pawn also has its own power and should not be taken lightly.