Checkmate

Overview: Betrayal
John has been compromised, corrupted, by consulting criminal. Sherlock was devastated, to say the least Sherlock spirals down into darkness, the only source of comfort at the tips of needles and razor blades. He was willing to make a deal with the devil.
Redemption comes in the form of the most unlikely source: an old enemy. Sherlock forms an uneasy alliance with the second most dangerous man in London. Sherlock makes a deal with the devil. Moriarty had stolen his best friend, it was time for him to return the favor for payback, and the gloves come off. The line between friend and foe blurs.