"Sherlock, I think we need to talk.

With anyone else, those words would have sparked a response of panic and fear. In a normal relationship, the one hearing those words would have immediately gone on notice, wondering what types of horror awaited them in the coming conversation; scenarios running through their head, each one worse than the last.

Sherlock was not anyone else. "We talk all the time, John. Is there something in particular on your mind or do you wish to simply fill the silence with inane chatter?"

Rolling his eyes, John felt a small amount of his own tension slip away. A very small amount but noticeable nonetheless. "I have a specific topic in mind and one I think you might find interesting if you could actually stop what you are doing and look at me."

The clatter of tools on the table was followed by Sherlock joining him in the living room, sitting in his chair opposite John. John knew it was unusual for him to demand Sherlock's attention so fully so he could see the curiosity shining in his lover's eyes. "What do you want to discuss? Something to do with your meeting with Mycroft, that much is obvious."

Now that he was faced with telling Sherlock the truth, John hesitated. Mycroft and the rest of the family must have had a good reason for keeping it from him and John worried that Sherlock would react poorly and it would all be directed at him. Was he willing to risk his relationship and his livelihood so Sherlock could know the truth? The answer was obvious. Sherlock's well-being was the most important thing and he couldn't do everything necessary to protect himself if he didn't know.

"It does have to do with Mycroft but he only filled in a few gaps. The rest I already knew and I apologize for not telling you sooner." John fidgeted, not bothering to try and hide his nerves from Sherlock. He would see through any attempts that John made anyhow. "You should have known long before I came into your life but there is nothing I can say for your family's failure to tell you. I can only say I'm sorry for not doing it myself once I realized what was going on."

He was stalling and Sherlock knew it. Eyes narrowed, he sat forward and scrutinized every inch of John, who squirmed under the gaze. "You are suggesting that there is something about myself that I do not know? And it is clear that you believe that but I am more in tune with myself that almost anyone else I have ever met so I cannot imagine that there is anything you are going to tell me that I don't already know."

"You have multiple personalities," John blurted out if only to get Sherlock to stop talking. "Technically it's called dissociative identity disorder and you have had it for over twenty years according to your brother." Whatever Sherlock had been about to say died on his lips and he stared at John, gaping mutely while he continued. "They think something at school must have triggered it because That was when it first showed up. Or, rather, when he first showed up."

Sherlock was silent for a few minutes, considering everything John had told him. "I suppose of all the things you could have told me, that is one of the few that I wouldn't necessarily know about myself," he mused. He was taking it well, something for which John was thankful, though, at the same time, John was unsure whether Sherlock believed him or not. "So I have been having these episodes since I was in school? That was when I started developing my mind palace. I had always thought those blocks of time I lost were when I was there. I never considered that someone else was in control. Fascinating."

While he was glad that this was going as smoothly as he could have possibly hoped, John wondered if the final piece of the puzzle would be the one to set him over. He was considering how to tell Sherlock who the other person in his mind was when Sherlock beat him to the question.

"The other personality. Tell me about it. I would assume they are as brilliant as I am – it would be unusual to have an ordinary mind using my extraordinary one – but if my memory serves me, one personality rarely has influence over the other."

"He is brilliant," John hedged, really wishing Mycroft or Mummy Holmes could have done this years ago. "You could say your equal in every way. At first, I thought it was your subconscious acting out, you were so different and yet completely uninhibited. But your mind works in a very similar way, regardless of who is dominant at the time."

"He isn't a consulting detective, though. I would know if there was someone else claiming to be a consulting detective. Oh, don't tell me he actually works with the Yard. Lestrade would take advantage of that. He probably prefers him, doesn't he."

Shaking his head, John sighed, "Lestrade doesn't know. If he did, you would be in jail right now. Your brother has been protecting you all these years but I thought you deserve to know the truth." With a deep breath, John told him. "Your other personality is James Moriarty."

The silence appeared to carry out of 221B and out onto the street. There was no sound in the flat except the pounding of his own pulse in John's ears. He looked at Sherlock who stared straight ahead, unblinking and unseeing. While John knew something was going on in that great mind of his, John couldn't hazard a guess as to what that would be.
"Sherlock?" He asked after a few moments had passed. "Are you alright?"

"All this time, I've been fighting against myself?" The question was asked softly, rhetorically and John didn't bother to answer. He knew Sherlock wasn't talking to him right now. "It makes sense. Who else would have been brilliant enough to keep me entertained for so long? Wait, did you sleep with him?"

John's eyes widened comically, "Yes, I did. Rather hard to avoid when you go to sleep next to your partner and wake up next to a madman. Easier to play along than get myself killed. Not sure how you would have rationalized that one."

"Fascinating. I wonder if there is any way to test that. I'll have to consider a few experiments."

Focusing on the intellectual aspects of it may have been interesting to Sherlock but John found himself growing more annoyed as Sherlock ignored the more practical problem at hand. "Sherlock," he growled. "If you are Moriarty and Moriarty has killed people..." His prompt seemed to fall on deaf ears as Sherlock moved to throw himself on the sofa and templed his fingers under his chin. "Are you even listening to me?"

Heavy sigh of exasperation, Sherlock looked over at him, "OI course I am listening and I will be sure to ask him about it. I think it is time Moriarty and I had a meeting, don't you?"

"Meeting? Have no you not listened to anything I have said? How are you going to meet with someone who is part of your mind."

The look Sherlock gave him had John feeling as if he were back in Primary school and gave the wrong answer to a simple question. Then, when the two words fell from Sherlock's lips, John understood that the feeling was well deserved.

"Mind palace."

To this day, John still didn't quite understand how the mind palace worked and he certainly was no expert on multiple personalities but he could not see anything wrong with this idea. "Fine, go meet Jim. I'm sure you two will be great friends. And tell him that the next time he shows up, it's his turn to get the milk.."

"I highly doubt your shopping list will be the subject of conversation, John."

John huffed his annoyance, "Go to your mind palace, Sherlock. I'll be thankful for some peace and quiet for once."

Sherlock analyzed his face, looking for any sign of mockery or disapproval. "Alright. I think Moriarty and I have some unfinished business. When we are done, I believe you will only have one of us to deal with from now on."

With no more words forthcoming, Sherlock appeared to have retreated into himself, leaving John with the dawning horror that if they did succeed in getting rid of the other, what if Sherlock wasn't the victor?