Sherlock may be the detective between the two of them, but John put two and two together quickly, long before anyone on the Scotland Yard force. Yes, having some inside information helped him, but he felt confident that he still would have figured it before anyone else.

It started with John and Sherlock planning their wedding. They had been lovers for several months, having fallen into bed together following the horror on the Hollow in Dartmoor, but had lived together for almost a year prior to that point. John thought he knew the major members of the Holmes family, having met Mummy and been kidnapped by Mycroft many times over.

Because of this, it was a shock when Sherlock surprised him with, "Of course, my two nephews will expect to be part of the festivities." John realized that what had started as a simple ceremony at the registrar's office was getting more and more complicated by the day.

"Wait, there are more of you? How many siblings do you have that I don't know about?"

"Mycroft is more than enough, thank you," Sherlock stated, with the air of one who has to suffer through the stupidity of others on a daily basis. Glancing at John's face, he continued, "Yes, yes. Mycroft is married with kids, the whole thing. I used to mock him for it, but I guess I can't do that anymore, can I?" Sherlock barely looked up from his computer screen during this exchange, as though it bored him to tears while John felt his whole axis tilt suddenly to one side.

"Is it Anthea?" he asked, as she was the only person other then themselves he had ever seen with Sherlock's poised older sibling.

Sherlock scoffed, "Anthea? Really, John? Does she seem my brother's type? No, but don't worry, you have met this person. Honestly, I can't believe that you haven't figured it out yet. As I always say, 'You see but you do not observe.' This is one of many instances of just such a thing." John chucked at his lover's long winded version of the word "No."

"So I know this person. Let's see if I can use the skills in deduction you have been trying to teach me. You have been avoiding the use of pronouns. That suggests the person is a man because you would not avoid pronouns if it was someone of the female gender, since that is the societal norm." Sherlock nodded, slightly pleased that John had indeed been paying attention. "A man I know or at least have met, is married to your brother. You're not going to tell me who it is, are you?"

Sherlock smiled a slightly sinister smile as he answered, "Of course not. But I have every confidence that you will figure it out. You are slightly above average in that respect."

John smirked before kissing the top of Sherlock's head, "Thanks for that, love. From you, it is high praise indeed. Tea?" Wandering off to the kitchen to start the kettle, he heard Sherlock's grunt of affirmation. "Can you at least tell me about your nephews? That would not give anything away, right?" No answer followed, but John shrugged it off as Sherlock being Sherlock.

It was not until later that night, over takeaway, that Sherlock brought up the conversation again. "Thomas and Liam are 3 and 5 respectively. Liam is just like my brother. I am terrified to see what he will be like as a teenager, though we can be sure the British government will be in Holmes family hands for at least another 70 years." He fell back into silence, and John frowned, feeling he had no more useful knowledge then he had prior. The next day he would realize just how wrong he was.