Author's note: I can't believe how many people read this story. And review it. I feel so honoured...Really, the response to this fic continues to make my day. Thank you.

I don't own anything.

"Alright, let me get this straight: Cairns ordered a criminal mastermind, who controls every crime in this city but nonetheless leads a life as a well-known psychiatrist and professor, to put a hit on Carey, and said criminal mastermind told his hit man to spear the victim with his own harpoon because he enjoys stuff like that, and he knew you were on the case when you surprised his sniper in the victim's house, so he had Cairns shot in front of you".

Mycroft had to admit that, put like that, it sounded rather unbelievable.

Lestrade put his head in his hands and sighed. "Life was easy" he grumbled, running his hands through his hair and finally crossing them behind his head, glaring at Mycroft. "Mind you, I'm not saying "good" or "interesting" but "easy". So I didn't solve many cases. So even when I knew who had committed the crime, I couldn't arrest the bastard because there was no evidence. So I had no friends. So I lived with a wife I didn't love anymore and who apparently cheated on me. So I didn't even notice I was alive most of the time. So what? It was easy, wonderfully easy, and then you decided to casually stride into my office with your bloody umbrella and your bloody suit and your bloody condescending attitude..."

"I'm informed that is my usual "attitude" as you so eloquently put it" Mycroft interrupted, and Lestrade stared at him. For a moment, the elder Holmes wondered if the DI was going to throw him out of his office.

Then, unexpectedly, Greg started to laugh.

Mycroft decided it was best to wait for this to subside, so he simply looked on until the DI gasped for air.

"My God – are you always like this?"

"Like what?" Mycroft asked.

"So polite and correct and – God, I can't remember the last time I laughed so much".

He looked at Mycroft, raising an eyebrow. "The question is: what do I do with you?"

Mycroft had been aware that there was a chance that Lestrade would arrest him – the man was still a police officer, and he had broken into a house – but it would only be a slight inconvenience. He would be out of the cell in ten minutes.

Greg seemed to come to a decision and shook his head. "Forget it. Breaking and entering isn't even our division".

"And what about the case?" Mycroft asked, "didn't we hinder your investigation?"

Greg laughed again. "Trust me, it's safe to say the only who has "hindered my investigations" in the past few years is me". He inclined his head to the right side and scrutinized Mycroft once again.

"You are right, though but – I trust you. I have no idea why, but I do".

Mycroft decided that "because we were friends in another universe" wasn't a good answer, so he said nothing.

"Sit down" Greg said, and, once Mycroft had obeyed, he added, "You think you can bring down this – this –" he searched for the name and found it before Mycroft could help out, "Moriarty. Officially. Without him killing you somewhere down the line".

"He wants us to try."

"What makes you think he'll play fair? Why would he even give you a chance?"

"Because" Mycroft replied with conviction, "he is bored and he wants someone to play with".

Greg sighed. "You geniuses have strange hobbies".

Mycroft chose not to comment.

"There is, however, one thing I still don't understand" Greg said, and Mycroft tensed. He had feared that the man Sherlock had once described as "the best Scotland Yard has to offer" (albeit in a slightly condescending tone) would notice what he had let out. He hadn't told him about Carl Powers, or the skull, or how long he had known Moriarty in this universe, although he had made clear that he knew him quite well.

The reason he had suppressed all of this was simple: He didn't know how to explain it. He could always make up a story about stumbling over some documents or Moriarty letting his mask slip – he hadn't spent his life in politics for nothing – but there was always the risk that Lestrade would want to see proof.

"From the way you talked about Moriarty, I gather you both knew him rather well – for years, probably – before you started to suspect that something was amiss. When and why did you suspect something?"

Just as Mycroft had thought, then. He swallowed and said, slowly, hoping it would be enough, "Yes, we knew each other for quite a while. In fact he has been my brother's best friend for over twenty years. I can't really say when I started to suspect something – there were just moments when I could see his true nature, just behind his eyes. Moments when he thought no one was watching him. Moments when he reacted too quickly or too slowly or not at all as one would have expected."

Lestrade frowned, and Mycroft, for once, couldn't read what he was thinking. It was disquieting.

Finally, he nodded, and Mycroft managed not to let show the relief he felt on his face.

"Instinct, then. I can live with that".

Something about the words he chose – "live with that" instead of "believe that" – told Mycroft that the DI had his suspicions, but wouldn't voice them, as long as Mycroft played fair with him during this case. It was unspoken agreement they both understood.

Greg stood up. "So, when do I get to meet the second part of the dynamic duo?"

"Sherlock is at work" Mycroft answered, glad that this at least wasn't a lie.

"What does Mr. "several PhDs" do for a living anyway?" the DI asked, grabbing his coat. "I know that he's a scientist, but other than that..."

"He works independently for several labs." Mycroft answered, realizing that he didn't know what his brother was working on, that he hadn't even asked. No wonder Sherlock had looked so disappointed when he left today. Mycroft was the only brother he had for the moment, and he didn't seem to care about him. He told himself, as he had so often done in the course of his life, when it came to Sherlock, that feeling guilty wouldn't change anything, especially not in a world that wasn't his own.

As always, it didn't really work, but he told himself it did.

"And now he's become a detective. And you occupy a minor position in the government. Your parents must be proud".

There was a slightly sarcastic undertone in his voice, but other than that, Lestrade seemed genuinely curious and obviously considered this polite conversation. Mycroft stiffened; he couldn't help it. The DI noticed and bit his lip.

"I'm sorry. I remember your brother told me you raised him. I didn't mean to – "

"It's fine" Mycroft answered quickly, instinctively reverting to John's way of dealing with uncomfortable conversations. "It's all fine".

Lestrade didn't look convinced, so Mycroft asked, "Where are we going, if you don't mind me asking?"

Greg rolled his eyes. "You don't expect me to take down a criminal mastermind in my office when we don't have any proof that he is a criminal mastermind to begin with, do you? I don't want to lose my job".

"Without me, you wouldn't even be doing your job right now" Mycroft shot back, and Greg merely smirked.

"The fact that you are right doesn't change anything about my previous statement. Plus, I think Sherlock and I need to clear the air before we even start to chase Moriarty. So, off to the Holmes mansion".

Mycroft deigned it below his dignity to make a sarcastic remark about "Holmes mansion". It was difficult enough to grasp that Greg felt he and Sherlock had to "clear the air"; the only time they had had to do that before had been, if he remembered correctly, was after Sherlock had returned, and even then, he didn't think that any forgiveness had to be bestowed in the first place. The DI and his brother understood one another in a way no one else could, for the simple reason that they both felt the need to solve crimes, couldn't live without it. The DI had chosen a more conventional path, yes, but other than that, their work ethics were surprisingly alike, which was why Greg had never really been angry at Sherlock even if he had stolen evidence or gone to arrest a suspect without telling anyone.

Now, of course, in this world, they didn't have that understanding. Sherlock had poured his energy into experiments and discoveries, rather than crime solving, and wouldn't sympathize with Lestrade, even if he turned out to be the DI Mycroft remembered after all; And Greg, while by no means stupid, would not comprehend a single one of Sherlock's experiment.

In this world, they were simply not made to be friends. But Greg was right, they had to at least build up something like a working relationship.

Which, remembering the only conversation they had had so far, would probably not be easy.

Sherlock would see that Greg could be useful to them, however; and he trusted Mycroft enough that he could make his brother be polite to the detective.

Mycroft didn't like the thought of manipulating Sherlock – and yet, it couldn't be helped if it was the only way to get his brother to work with the DI. Perhaps he would do it simply because he knew it to be the best thing to do under the circumstances, though. He would have to wait and see.

They took Greg's car and drove back to the house. Sherlock hadn't returned yet, but that was only to be expected. If the employees of the lab didn't know how to deal with the experiment, something big must have gone wrong.

Greg immediately went into the living room, and with a strange feeling of regret Mycroft remembered that the DI had only done that in his world after he had been to his house several times.

"So you raised him" Greg said, once they were both seated.

Mycroft nodded.

"How old where you?" the DI asked. "I'm sorry, I'm just curious. How old where you when..."

He trailed off and Mycroft realized he didn't know whether their parents were dead or had simply been inadequate, so he said, "I was eighteen and Sherlock eleven. I took him with me when I left for university – he didn't want to be left alone". He was confident that the DI would hear the unspoken "with our parents" and he was proven right when Greg simply nodded.

"You are a good brother. I don't think I could have handled looking after a young boy while trying to complete my education".

The DI fell silent, and Mycroft had to fight the urge to tell him that he hadn't handled it, and furthermore, that he wasn't even sure that he could have handled it as his counterpart in the world had done. Maybe this Mycroft was better than him; maybe he had been born with a warmer heart, maybe living with Sherlock and studying at the same time hadn't been a problem for him at all.

Maybe he was simply deficient. That he didn't belong into this world was obvious; and he wanted nothing more than to return home. This world made him see just how empty his life truly was, and how it could have been –

If he would even have been able to do the right thing.

Maybe he had never deserved a brother like Sherlock Holmes to begin with.

Author's note: Bonding over crime fighting – the best friendships start this way. I thought it was a good point at the story to return to the other universe and see what Mycroft was up to.

I hope you liked it.