Sherlock was curious. In truth, he had always been curious, but knew better than to let what he perceived to be his weakness show. It was far better to let the world believe him to be a 'machine', a man who could - in his own words - divorce himself from feelings. However, as he watched the people in his life meet partners to connect with on an emotional level that was unfamiliar to him, Sherlock's curiosity deepened. Mrs Hudson had finally started to date somebody after the execution of her husband some years ago, albeit with somebody who unfortunately already had a wife. John's latest attempt at dating, this time with Jeanette, had proved to be unsuccessful, which admittedly could be linked to John's unwavering commitment to Sherlock. Even Lestrade had been in the process of getting back together with his wife, however misguided Sherlock believed their latest attempt to be. But who did Sherlock have? It seemed that both John and their friends would have been happy if Sherlock had embarked on a relationship with Irene Adler, had the fact that she was a traitor and known confederate of Sherlock's arch-enemy Moriarty remained undetected. Sherlock had allowed himself to entertain the idea of a relationship with Irene, though he would never admit this to anyone because he had permanently dismissed it within three minutes of meeting her. Although there was no doubt in Sherlock's mind that Irene would have prevented him from becoming bored - boredom was one of the main banes of his life - he could never trust her, and even if he could, their relationship would almost certainly drive John away. Sherlock was aware that, of all the things he had lost, nothing would compare to the pain of losing John. If John approached him, informing him that he would be leaving 221B for good, no matter the reason, Sherlock knew that he would not be able to cope. John was everything that Sherlock was not, and vice versa. They complimented each other, completed each other, like yin and yang, or a hypothesis with corroborating evidence.

"Sherlock?"

The detective did not appear to hear to John's call. No part of his body even flinched at the word which had disturbed the silence. He simply remained where he stood, staring out of the window onto the street below.

"Sherlock, I'm going out for a bit."

Sherlock swiveled round and saw John standing in the doorway. "Why?"

"I have a date."

Sherlock rolled his eyes. John understood this to be a sign of acknowledgement, that he could go on his date without any of the usual arguments that started when John's interest in dating was rekindled. Sherlock knew better. He knew what John was thinking, and it was accurate to an extent, but secretly Sherlock just wanted him to stay at home. He failed to see why John couldn't understand that their life together should be enough for him. John had never been very successful with dating anyway, for which Sherlock took some credit. Again, he would never admit to this, but Sherlock had deliberately foiled some of John's dates. He couldn't pinpoint the exact reason why he had done it, but understood enough to know that it wasn't out of malice or revenge. These women had done nothing wrong. Sherlock had found gate-crashing John's circus date with Sarah particularly amusing, and when Jeanette had come round for the Christmas party at 221B, Sherlock 'couldn't remember' which date she was. Of course he hadn't really forgotten, Sherlock never forgot anything. John should have known better than to fall for this ploy, which would, in turn, have given him his first clue to deducing Sherlock's true feelings: Sherlock was concerned that if John found the right woman, he would leave Sherlock behind.

"Are you even listening to me, Sherlock?"

"What, sorry? Oh yes, of course. A date." It was obvious now. John was wearing a new blue shirt, a tie, smart trousers and shoes. His hair had been combed, and there was a faint waft of cologne in the air. "Which one is it this time?"

"Anthea."

That stopped Sherlock in his tracks. He had been expecting to hear that John was planning another futile attempt at dating Sarah or Jeanette again. "Mycroft's assistant?"

"Yes. She telephoned earlier, asking if I'd like to take her out to dinner. Problem?"

Sherlock could not understand why Anthea would agree to date John now, when she had always rebuffed his advances in the past. What had changed? Surely Mycroft would not sink so low as to use Anthea to spy on them both? Mycroft had never been the most subtle of people, but this was all a bit too obvious, even for him. Sherlock tapped out a text and set it to his brother.

Stop using your assistant to spy on John and I. SH

"Right, well, I'm going now anyway."

"Where are you taking her?"

"Angelo's restaurant. Can you believe that she's never been there? It's one of the best restaurants in London!"

"There are many things that I don't believe, John, but this is one that I simply don't care about."

Sherlock's phone bleeped with a text alert. By reading his brother's reply, Sherlock missed the scowl on John's face.

Your deductions are inaccurate. Anthea requested permission to date John, I have not meddled. MH

This was unexpected; Anthea's desire to date John was genuine. Sherlock still failed to understand what had changed, and concluded that the only way to satisfy his curiosity was by secretly joining John on his date. If confronted, Sherlock could always defend his actions by arguing that John needed to be protected. The world's only consulting detective had many enemies, and if any of them had the slightest inkling of how Sherlock felt about John, perhaps even understanding Sherlock's feelings better than he did himself, then it was likely that the doctor would become their prime target.

"Right, well I'm going now to meet her." John's voice broke the silence again.

Sherlock pocketed his phone. "Fine. I might not be here when you get back."

John pulled a face which suggested that he was confused about something. Sherlock couldn't see what he could possibly be confused about. He had said that he might not be in the flat when John returned, ergo it was obvious that Sherlock was planning on going out too. John didn't need to know where though.

"Where are you going?"

"Out. That's why I might not be here when you return."

As Sherlock read John's expression, he realised how John had interpreted his words, and guilt began to stir in his stomach. "I only meant that I'm going out tonight. I'll be coming back." John had thought that Sherlock might disappear, as he sometimes did when he was investigating a case. The length of time that he was gone varied. Sometimes it was overnight, other times it could be for a week or more.

John shrugged his shoulders in what he hoped Sherlock perceived to be a nonchalant way. "Okay, fine. See you later." He turned and began to descend the stairs leading to Baker Street. He failed to notice Sherlock's soft footsteps behind him, or see Sherlock's face in the cab behind him as he looked into his own cab's rearview mirror. It was possible to excuse John's ignorance, as his thoughts were preoccupied as to why his dates didn't bother Sherlock, when he actually wanted them to. He wanted to provoke Sherlock, to understand the feelings that were undoubtedly generated by the genius's heart. John wanted to know where he stood with a man who could do anything and everything, and still chose to live with him.