This is the first in a series of 'side conversations' that will hopefully dovetail with Fratros, Eros and Agape. I'm sticking rigorously to telling that story from John's POV, so this is a way of filling in some of the other details to flesh out the story a little.

This story fits into the timeframe alongside Chapter 11 of Fratros, when John is visiting Mrs Hudson in 221B.

Because you didn't really think that Mary was just providing a shoulder for a friend to cry on did you?

As ever, thank you all so much for reading, and please do let me know what you think.

She knew.

Before she saw the tips of his polished, hand-crafted shoes through the open door.

Before she saw his overcoat and umbrella on the thoughtfully provided hat stand.

Before she saw his perfectly tailored suit. She knew that it was Mycroft Holmes waiting for her behind that door.

'I'm surprised that it took you so long,' she said, as she walked in and took the indicated seat opposite him. 'Nice place, by the way. What is it?'

'A place for people to do business when they would rather not be disturbed - or overheard. And what makes you think that I didn't know?'

He had a heavy document file in front of him which he picked up and dropped on the desk in front of her with a thud. She didn't need to open it to know what it contained.

'And let you still let me go back to talk to Sherlock?'

'That was a calculated risk.'

'To what advantage?'

'Should your husband discover your true identity, then your position will become untenable. And that would not be to anyone's benefit.'

'Meaning?'

'Meaning that you seem to have finally got Charles Augustus Magnussen's attention, Mrs Watson, or should I call you Miss Adair? Why waste that advantage?'

'And your brother's safety?' she asked, ignoring the reference to her real identity, and refusing to give him the satisfaction of lifting the cover of the file in front of her.

'If you had wished to kill my brother, Miss Adair, then you would have done so three nights ago. More to the point, my brother's silence on the subject seems to indicate that he is of the same opinion.'

'So why am I here?'

'I wish to make you a job offer. But first, I would like to hear to know why you chose to shoot Sherlock.'

'You already know why.'

'In order to prove to Charles Augustus Magnussen that you were not a woman to be trifled with.'

'Well deduced, Mycroft.'

'And yet something prevented you from proving that conclusively. Sentiment? Surely not. Ah, of course. John Watson. John Watson prevented you.'

'Losing Sherlock once nearly destroyed him. I wouldn't do that to him. Not again,' Mary admitted, reluctantly.

'So instead you gave him the opportunity to save his friend in a way that had been denied him two years ago. Trusting that he had the pre-hospital skills to keep Sherlock alive until they could get him to surgery. It was a bet that you nearly lost.'

'But I didn't.'

'Fortunately not. Had you done so, then I hardly need tell you that you would not be sitting here now.'

'What are you offering Mycroft?'

'Why would I be offering anything?'

'Because if you didn't want to make a deal, then you would have had me arrested by now. The contents of that file alone, are enough to put me away for a very, very long time.'

'They are enough to do more than that in several American states, as you are well aware.'

'So - what are you suggesting?'

'Firstly, an assurance of my brother's safety.'

'I have no quarrel with Sherlock, Mycroft, as you well know.'

'So I have your word?'

'Of course.'

'Even should he threaten to tell John?'

Mary hesitated for only a split second. 'He wouldn't tell John.'

'But if he did?'

'Then the reasons for keeping him alive would remain. I wouldn't do that to John.'

'Good. And now to the other matter. It will not have escaped your notice that I am not the only person in possession of a copy of this file.'

'Did you get it from him?' Mary struggled to keep her voice calm and level, years of training fighting against a sense of rising panic.

'And let him know that I was aware who you were? No. I have my own sources of information. Once we had cracked the code as it were, realised that you were not who you said that you were, then photo-recognition software did the rest. We have our own methods of research.'

Mary nodded and looked at the floor, composed herself, then looked back at Mycroft. 'So what is it that you want, Mycroft?'

'As I said, I wish to make you a job offer.'

'Go on.'

'I want you to keep my brother away from Charles Augustus Magnussen.'

Mary laughed out loud. 'You really think that I can do that?'

'No, but I think that John Watson can.'

'But John doesn't know, can't know, that I'm involved.'

'Precisely. And that is your line to Sherlock. That if he persists in her pursuit of Magnussen, then Magnussen will use his pressure point - you, to get to John. If John loses you, then he loses his child also. Even my brother, single minded and obstreperous as he is, would not do that to John Watson.'

'Sentiment?' Mary asked. 'You're asking me to appeal to Sherlock's sense of sentiment?'

'I'm asking you to remind him of a promise that he made on your wedding day. To protect you and John above all else.'

'And why would he do that?'

'Because he loves John Watson, Miss Adair, as you are well aware.'

'I wish you wouldn't call me that,' she muttered.

'What would you prefer?'

'Mary. Mary will do just fine. Is that why you didn't come to the wedding? Because you knew?'

'No, I didn't come to the wedding because I dislike weddings.'

'How long have you known - only that file of information hasn't been compiled since your brother said my name this morning.'

'Since the bonfire.'

'The bonfire? How did you - oh, of course, it would have been in the report with the terrorism attack. But I didn't do anything to rescue John, Sherlock did it all.'

'Yes, but the texts were sent to you.'

'To pass onto Sherlock.'

'Incorrect. They were went to you in the knowledge that you would follow the clues and save John. Magnussen was proving that John is your pressure point, and so he remains.'

'And if I do this for you? If I keep Sherlock away from Magnussen, what then?'

'Then your past identity remains a secret.'

'Until you decide to call in the favour?'

'I may have a job offer for you in the future, certainly. A little bit of freelancing, if you will.'

'I'm retired, Mycroft.'

'In this game, you never retire, my dear, ' Mycroft said, standing up and reclaiming his coat and umbrella, 'as you proved the other night. Now just keep my brother away from Magnussen, will you? There's a good girl.'

'Mycroft, wait.' Mary said firmly, as he reached the door. He turned, hand still on the door handle. 'You know what kind of man Magnussen is. Why keep him safe?'

'Oh I never said that I was going to keep him safe,' he replied, and then the door clicked shut behind him and he was gone.