AN: Another important one. Still don't own any of them.

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Mycroft shook his head and opened his mouth to say something, but Irene Adler stopped him with her raised hand: "No, I know you're only offering me a bed in one of your spare rooms. Though I do wonder...why? Both of us know you'd let nothing slip, and would not become enamoured with me, or anything as ridiculous as that. So why not?"

"My brother would not appreciate it."

She raised her eyebrows. "We are hardly in a committed relationship."

"Nevertheless."

Her lips curled in a sardonic smile. "If Sherlock Holmes is going to mind me having sex with other people, then I'm not going to stay in London long."

"Oh, he doesn't," Mycroft assured her calmly. "He would mind me, though."

"Why?"

"Because he knows the other people don't matter."

A lazy grin spread over Miss Adler's face. "And you think you would?"

"That is immaterial," though in fact yes, he did think he would, though likely not as much as his brother. "We were discussing Sherlock's...sentiments."

She hesitated for a moment, then: "He wouldn't have to know."

Mycroft looked at her steadily for a long while, and then said: "Are you really that desperate to be able to claim that you bedded the most powerful man in England?" There wasn't a trace of boasting in his voice as he stated the simple truth.

She was smiling again. "No, I'm just curious. It's bound to be interesting. Most people are so boring, you know..."

If he was honest, Mycroft was curious too. She was the professional, after all. But it didn't change anything, and besides, he knew that for a large part, she was testing him, wanting to know how he'd react. And if he'd agreed, then later, if it was advantageous to her, she'd use his acquiescence to drive a wedge between him and Sherlock – well, even more of a wedge. If he'd needed additional reasons to refuse beside his...regard...for Sherlock, here they were. "I'm afraid you'll simply have to be disappointed." He paused, then changed the topic: "Who have been the 'most people' you've been...in touch with lately?"

"Oh, you know. Here and there."

He just looked at her.

"I'm not going to give you any details, you know that."

"Unless you give me at least something, a general idea, I'm afraid I'll be forced to make your life rather complicated."

"That could turn out a little different than you imagine – I am back to having some safety checks. But I do actually want to see Sherlock, and am well aware you could prevent that, so...I couldn't go back to being a professional, naturally, that would have been too obvious. So I became a mistress instead – of various people. Various important people. At crucial times of their lives."

The dots connected in Mycroft's head. "Ah. Isabel Xie."

"Very good, Mr. Holmes."

Isabel Xie had been the mistress of many prominent politicians, mostly South American, during the last two years. Men seemed to be obsessed by her, and what was even more interesting, secret services around the world seemed incapable of getting a clear picture of her face. Usually, there were big sunglasses and a wide-brimmed hat; sometimes, it was her hair obscuring her face, or a shawl wrapped around it in such a way that nothing could really be seen. She never seemed to fly or cross any border officially (not under that name, at least, and somehow no one ever managed to follow her to a crossing to find out if there was some other), and they only got her name from her past lovers remembering her.

Mycroft never connected her with Miss Adler simply because the parts of her face he did see on the photos looked so unlike the woman he remembered.

He knew why now, of course.

It was a bit puzzling that he hadn't realized the connection the moment he saw Irene Adler standing in front of his house, but then, collagen lips all looked so very much alike, and there was never much more to be seen from Isabel Xie on all those pictures.

"In that case, may I make a business proposal?" She was going to be an information mine.

She smiled wolfishly. "I'll think about it," she said.

Mycroft suddenly had another reason to wish she'd stay with Sherlock for a while.

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Mycroft really wanted to know what Irene Adler's first meeting with Sherlock would go like, so he gave her a small microphone and a camera in fashionable glasses in the morning, politely pointing out that his threats still stood if she didn't cooperate, and she laughed and took it.

So that morning, he shut himself in his office and watched.

Irene was greeted at the door by Mary Watson, who was apparently visiting, and then he saw her turn into the room and call: "Sherlock, there is a woman here to visit you, says she knows you? Half-Asian, hair dyed red, lip job?"

Not the most flattering description of herself Irene Adler has ever heard, Mycroft was sure, yet she should be content. This was precisely the effect she had been going for.

He heard his brother reply something indistinguishable, and then Miss Adler was saying: "He did a case for me once."

Mary repeated the words loudly, and Mycroft could hear Sherlock approaching the door. "Oh, a client," he said, and then he got close enough to see the visitor.

Mycroft hadn't though his brother capable of such an expression, and he had seen him with Dr. Watson.

That complete, absolute happiness that showed in his eyes in that moment...he had to quench the strong jealous impulse to feel angry that this was never in his brother's eyes when he saw him. It was curious that it still bothered him, anyway – he should be used to it by now. Apparently, he wasn't. He remembered that time he got his brother back from Serbia, how he assumed Mycroft had enjoyed watching him getting hurt, even though he felt every blow like his own, and then the only one he could ask about was John Watson...Mycroft knew he hadn't really been at his best that day, and he was sorry, but thought that, all things considered, he could be given some reprieve.

While these thoughts passed through his head, his brother got his expression under control, turned to Mary and said: "Do you think you could give us a...moment?"

She just smiled. "Oh, of course! I was leaving already anyway!" She lied blatantly, picked up Shirley sleeping in a basket, and disappeared.

Mycroft watched Sherlock turn to Irene Adler, then. "You are...back." He said.

"Yes."

"Why?"

"I thought you could use some help against Jim, seeing that I doubt you want to spend another two years dead at the end of this round."

"You're one to talk."

Mycroft's phone beeped at this moment. Noting that it was from Mary, he just noded in satisfaction at her speed and went back to watching.

"Yes, well, I did learn my lesson," Miss Adler replied. "This time I'm here to fight with you, not against you."

Sherlock sighed. "Things were easier in the Marshall Islands, weren't they?" Ah, so that's where they'd gone, Mycroft thought. "No loyalty issues. Here, however..."

Mycroft was extremely proud of his brother. It appeared he had learned his lesson, too.

Irene Adler looked out of a window, regaling Mycroft with the sight of Baker Street he wasn't interested in in the slightest. "I don't have any way to prove myself," she admitted. "But you know I don't have any reason to help Moriarty."

"A chance at your old life back?"

"Not even he is that powerful. Besides, I have gotten somewhere in those three years. I don't feel quite that desperate."

"If you have gotten somewhere, why come back here?"

And again Mycroft was struck by how much he understood this woman, the closest his brother had ever had to a love. He knew why she'd come back, and he understood precisely why she didn't want to say. He had been almost grateful to that terrorist group for targeting London, a year ago, because it gave him a good reason to go and get his brother from Serbia without having to say anything of the sort. Irene Adler had wanted to use Moriarty in the same way, but it didn't work.

"You are right, it was easier in the Marshall Islands," she said.

There was a long silence, then Sherlock said carefully. "Even given that I can't trust you...I believe that if your intention were to kill me or incapacitate me to deliver me to Moriarty, you'd have already done so. So the plan would have rather be to learn of, and disturb, my plans. Which means that I'm in no immediate danger."

She turned to him then, and Mycroft could feel her eyebrow raising in her tone, as she said: "Brilliant work, Mr. Consulting Detective. But," she added, stepping closer to him, "I believe you forgot to take one kind of danger into account..." and then, whispering into his ear, "can I take your pulse?"

He took of her glasses, and Mycroft turned off the microphone on his end soon after that.

He looked at that message from Mary. It said: "There's a woman in Sherlock's flat, seems a romantic interest, improbable as that sounds. Any orders?"

He quickly typed back: "Stand down. I know about her," and went back to his work with a sigh.

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Entirely as expected, Mary turned up in Mycroft's office that afternoon, and very reasonably demanded an explanation. She was right: she could hardly be expected to do her job well if she lacked crucial information.

"She was something of an unexpected factor," he explained. "She only turned up last night."

"Yes, but Sherlock obviously knows her from the past. Why have I never heard of her?"

"Oh, but you have." Mycroft paused, but there was no avoiding this. She'd know very soon from John anyway. "That was Irene Adler."

"That was...what? Wasn't she supposed to be dead too? Does anybody actually stay dead around here?"

Mycroft almost chuckled. "Not many people, no. No one important. But anyway, I always knew she wasn't dead – Sherlock saved her life."

Mary frowned. "You never told John."

"No. We needed to protect her cover. I never even talked about it with Sherlock, though I assume he knew I knew – he didn't really try that hard to mask it."

"You know, sometimes I wonder why John even talks to either of you any more."

Mycroft raised his eyebrows. "This one was at least partly his fault. Sherlock left for a month to save Miss Adler – Sherlock, who never leaves London – and I told John the approximate time of Adler's supposed death. He should have been able to put two and two together."

Mary looked at him incredulously. "Oh yes, how stupid of him to trust his best friend and his brother."

"You know, coming from you, I find that remark rather ironic."

She laughed. "Point taken. That just makes me feel sorrier about John, though. No one trustworthy around him at all..."

"But we are all trustworthy. We just don't always speak the truth."

Mrs. Watson smiled at his distinction. "So," she said then, "I'm to just let your brother spend time with Irene Adler, of all people?"

"Yes. I know his taste could use some improvement, but this is who he chose, and he would never forgive me – or get over it entirely – if I intervened. So you don't have to concern yourself with her, but don't worry, I have her watched."

"I never doubted that."

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Mycroft was not entirely surprised that, during his next meeting with Mae Ollivier, she smiled at him and said: "I've heard that you had a lady visitor overnight recently. Should I be jealous?"

"I must have missed the moment when our relationship, such as it is, progressed to the point where jealousy is an acceptable emotion."

"Jealousy is never an acceptable emotion," she remarked, making him think of his anger towards John Watson or Irene Adler. "But I have to admit that I'm intrigued."

"I do agree that such behaviour on my part is rather unusual."

"Oh well, keep your secrets. Though I'd still like to know why I was never invited to your real house, and she was."

"This particular lady can be very persuasive, and persistent."

Miss Ollivier raised her eyebrow. "Perhaps I should try that too."

Unfortunately, there was no way he'd ever invite Mae Ollivier to his house. Even though...people were starting to talk. Vernon had been the first, but he had heard mentions about how long his affair was taking from Henry and Edwin too. There weren't any accusations yet, but he knew it was only a matter of time. He also knew it was the secrecy doing this – as irrational as it was, the fact that it wasn't an official relationship made people assume he was doing something clandestine, like betraying his country. So perhaps there were some advantages to it...

"Perhaps I might consider yielding."

She blinked, apparently shocked. For a good reason, too.

He explained: "We have both let some people know about this relationship, as a basic security precaution, but it has been going on for a long time. There is actually no reason why we couldn't make this an official...commitment. And there are some reasons to do it."

She considered. "Appearing in public would mean..."

"...higher risk for both of us, yes, because we each could be used as leverage against the other. But do you honestly believe that anyone who knows we're important would think we were...emotionally attached? Especially if they knew the reason for this relationship? The danger is minimal."

She nodded carefully. "And there are benefits, yes. It would stop the gossip, of course, but also, frankly, it would be less bother. Getting away to semi-secret flats is time-consuming."

"There would be privacy issues," he pointed out, not completely convinced of this plan himself.

"Yes..." She paused. "Obviously I can't afford to have you roaming freely in my house, or you me in yours. But we would be pretending to be a freshly formed couple, so no living together would be expected. Just one staying overnight in the other's house from time to time. We could probably keep an eye on each other – and don't forget that for every opportunity for me to search your house, you'd get one in mine."

That was certainly a lure difficult to resist. And he could move some of the sensitive things to his club or to his office, anyway – though of course she would likely do the same. He could only hope that the Embassy was smaller and she didn't have a club, but then again, she did have an aristocratic sister. Though...no. There was no way Miss Ollivier would leave anything the least bit sensitive in reach of all those secret agents constantly trying to earn their bread around her sister.

There was one other thing that bothered him about it.

"It would also entail a lot of...pretending."

It was one of the things he really enjoyed about her company, that he didn't have to pretend much.

Surprisingly, she shook her head. "That's the first thing I thought of, but not really. No one who knows us would take us for the PDA kid of people," Mycroft frowned just hearing the acronym, the idea was too distasteful, and she smiled seemingly against herself, "so I think that, all things considered, we could act mostly normal. Perhaps some hand-holding in a restaurant, but only very exceptionally." She paused. "I'd have to think it through."

"Of course. It was an immediate idea, so I require time myself. Will a week suffice?"

"I think it should do just fine."

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AN: Mycroft's and Mary's business relationship, as presented here, was established in my stories Making A Deal and Getting A Job, in case you're interested. :)

Also, I'm writing a story about Irene and Sherlock in Karachi and after to explain how they got to this point in their relationship, but it's insanely difficult, because they both have to be a bit out of character (Irene being vulnerable and Sherlock being involved), and it's really hard to walk the line between just enough OOC and too much...so I don't actually know if it will ever be finished, but let me just say that by Sherlock's behavior towards Janine in HLV, even though he didn't sleep with her, I think it's perfectly obvious that he has already been in a physical relationship before (though maybe hasn't gone 'all the way') – he's too comfortable with her around. So the relationship must have happened in Karachi and after...