"Subject is leaving the flat."

"Pick her up and bring her in," he intoned calmly into his intercom. He left his office suite and walked down the hall to a room filled with monitors—his own private viewing area. The chief technician at the main control board looked up as he entered the room. "Baker Street," said Mycroft Holmes. Instantly a view of Baker Street from the CCTV cameras in front of his brother's flat appeared on the nearest monitor. And there she was, the latest subject of his scrutiny, leaving 221B and walking towards the tube station.

Mary Morstan had been on his radar screen for six months now. A background check had shown her to be an exceptional young woman, well-educated, no living family, with no red flags to make her a threat. Mycroft had thus far left her alone. After all, if he had personally interviewed every one of Dr Watson's female companions since he'd moved in with Sherlock, Mycroft would have had little time left to spend running the government.

This subject was different. She had lasted six months, for one thing. Video of her interactions with Sherlock had proved interesting, also—she seemed to have established a rapport with his brother which few people had ever managed to do. And now, the dénouement: it had come to Mycroft's attention that John Watson had proposed to the subject last night. It was time to meet Mary Morstan in person.

He watched her notice the limo as it pulled up alongside her. She slowed down, watching it warily, and the driver spoke to her out of the window. Stopping, she pulled out her mobile and quickly sent off a text before climbing obligingly into the back of the black vehicle. "Find out who that text went to and what it says," Mycroft demanded. It took a few seconds; then the number appeared on one of the screens. He did not need to ask whose it was: he had called it himself hundreds of times over the past two years. The subject's text read, "Limo's here." The reply from John Watson was, apart from the more colourful profanities: "Tell him to piss off. And say hi to Anthea."

"Switch to the interior camera," Mycroft snapped. He could now see the subject, reading her text from John and laughing silently.

She turned to Mycroft's PA and said cheerfully, "You must be Anthea."

"Occasionally," Anthea smiled enigmatically, keeping her eyes on her blackberry.

"You're just as John described," Mary remarked.

"Sorry, John?" Anthea asked lightly. Mycroft shook his head. That was a mistake. Mary would never believe that Anthea did not remember John Watson. Now the subject was scrutinizing his PA with great care.

"You know. The lovely blonde soldier who told Mycroft Holmes where to get off."

Anthea's face and hands did not admit to any emotional response to this statement, but it is not possible to control one's blush response. Mary's smile was slightly wicked. "Good luck with that crush," she said.

"I've seen enough," Mycroft snorted. The subject had the advantage, of course, of being warned by both John and Sherlock as to how to deal with the British Government. He should have discussed this encounter more thoroughly with his PA. The subject was apparently not only intelligent but also highly observant. No wonder she got along so well with Sherlock; and she was obviously a perfect match for John. "Have you found any footage revealing her left hand since this morning?"

"No, sir, she walks with her hands in her pockets, unless she's using her phone. But then the phone itself prevents a clear view."

"Oh, well. It doesn't really matter." Mycroft stalked out to order preparations for the subject's arrival.

When he returned, the tech informed him that the subject had sent another text, this one to Sherlock's mobile. "Put it on a screen," Mycroft sighed.

"Big brother has kidnapped me," her message read. The reply from Sherlock was: "My condolences. Deny everything."

Mycroft shook his head. "That's meaningless. It's for my benefit, and not to be taken seriously. What was her reaction?"

"She seemed quite amused, sir," the tech admitted.

A few minutes later, an aide arrived to inform Mycroft that the subject had been placed in the receiving area and served tea. Mycroft let her sit alone for a few minutes, knowing that his opulent, richly-appointed receiving room tended to overawe most visitors. When he finally deigned to join his guest, she was indeed looking about her, appreciating the wealth and power this room represented. Her teacup and saucer were in her left hand, effectively hiding it from view.

"Miss Morstan," he greeted her grandly, his most diplomatic smile on his lips.

"Mr. Holmes," she returned brightly. She offered her right hand, and he took it graciously, bowing slightly.

"It's a pleasure to meet you at last." This was the beginning of an elaborate game of poker.

"I'm sure it is," she countered pleasantly. "However, I've got a phone. It would have been, perhaps, more beneficial to phone for an appointment at a mutually convenient time. On my phone."

Mycroft's lips remained in a tolerant smile. "I apologize for my manner of acquiring your cooperation in this meeting. Please believe me that it was necessary to be expedient. But shall we speak of more pleasant matters? For example, may I congratulate you on your engagement to Dr Watson?"

The subject set down her teacup and sat back, crossing her arms over her chest. Her cheerful demeanour disappeared. "No, you may not," she said frostily.

Mycroft did not allow his expression to change, but he was impressed with the force of her character. "I beg your pardon?"

Mary rose from her seat and held up her left hand for his inspection. "I believe you can see from my left hand that such a sentiment would be inappropriate," she said coolly.

"I see." Mycroft would not back down. "May I ask when the formal announcement will be made so I may offer my congratulations when it becomes appropriate?"

"A better question would be: why do you believe I am engaged to John Watson? Or to anyone, for that matter?" she demanded loftily.

"Please, be seated young lady," Mycroft said smoothly. She sat, this time on the very edge of the chair, and waited. "Dr Watson was seen two days ago at his bank, retrieving his grandmother's ring from his safety deposit box. Yesterday evening, he was seen at the door of your flat dressed in his best suit, carrying a bouquet of roses. A conclusion was drawn accordingly."

"I'm disappointed, Mr. Holmes. You're typically male, aren't you? I would have thought you'd be above all that. You think just because a man waves a ring in front of a girl, that she must automatically swoon into his arms and say 'yes'."

Mycroft countered this move swiftly. "You must admit, Miss Morstan, that your recent association with the doctor indicates that such an alliance between you would not be unexpected."

The subject sighed deeply, as if vexed to her very soul. "Your left hand, Mr. Holmes, please."

"I beg your pardon."

"Beg all you like. I showed you mine; now show me yours."

Bemused, Mycroft held up his left hand obligingly. He couldn't help but like this intriguing young woman. She was . . . interesting.

"So, I see you are unmarried. I suppose you may be excused for believing a woman must behave as a man might expect."

Mycroft could see that it would be useless for him to continue in this line of inquiry. He changed tactics. "What is your relationship to Sherlock Holmes?"

She held up her left hand again, chuckling. "Not his fiancée."

He shook his head impatiently. "Of course not. But as his brother, I am naturally concerned about him. After spending all last night with John, you spent all this morning with Sherlock."

"And now, apparently, I am spending all this afternoon with YOU. I AM a busy girl. What might I get up to next?" Mary laughed mischievously. "If you are suggesting that I threw John over for his best friend, you must think I'm very wicked indeed."

Mycroft suddenly realized he had made a tactical error. He had referred to John by his first name, showing an empathy with him that suggested friendship; or at the very least, an alliance between them born of common purpose. He realized then that this was not just an error but an actual feeling. He respected John Watson. More, he LIKED the man. Somewhere deep in the recesses of his being, Mycroft had been sentimentally rooting for John to win the hand of this delightful woman and was disappointed for his . . . friend. Still, he must rise above useless emotionalism and get to the point.

"Miss Morstan, it is imperative that you understand this. My brother and John Watson have a working relationship that must not be interfered with. It would be most regrettable if anything should happen to cause a rift between them." His tone left no question. This was a clear threat.

The subject—but no longer just a subject to Mycroft: a fascinating human being—leaned forward in her chair and looked him in the eye. "I know. I absolutely agree with you."

Mycroft was speechless.

Mary sat back again and smiled gently. "You have had me thoroughly investigated, I assume. If so, you will have found that I never lie; although I am not above deceit."

Mycroft smiled as well—his REAL smile. The one few human beings had ever witnessed. "You've never said that you're NOT engaged to John Watson."

She pulled the ring from her pocket and placed it on her left hand. "He proposed last night, as you guessed he would, and I accepted. We agreed to formally announce our engagement next week at his birthday party—in the meantime, we meant to keep it dark. Only John and I, Sherlock and Mrs. Hudson were to know about it. However, John guessed you would meddle. And Sherlock gave me the perfect idea to punish you for meddling."

"Deny everything." Mycroft couldn't help but laugh aloud.

"I'm done playing games, Mr. Holmes. I like you. And I know you have Sherlock's best interests at heart. You needn't worry, I assure you, because John and I also have his best interests at heart. He is as important to us as he is to you. I will have mercy on you, because you obviously love your brother, and let you know our plans. We intend to pool our resources, allowing John to quit his job at the clinic and work with Sherlock full-time. I hope this reassures you as to our intentions."

"Thank you for being so forthcoming," Mycroft said, feeling more relieved than he wanted to admit. "May I once again offer my most sincere congratulations, Miss Morstan? Or may I call you Mary?"

"Please do, Mycroft. We are something nearly like in-laws now, I suppose. Shall we call a truce and be friends?"

"I would be delighted, my dear," said Mycroft.