Sherlock, John and Kate were eating Sunday lunch in the pub, when a noise came from Sherlock's pocket that could only be described as suggestive. Sherlock reached for his phone, and checked the screen. Text. Kate looked from his calculating look to John's horrified one, and quickly realised that there was only one person that text could possibly be from.

She raised her eyebrows at Sherlock, who laughed and showed her the phone. It said: 'Dinner?'

'May I?' asked Kate.

'Be my guest,' Sherlock said. John meanwhile was looking from one to the other of them giving a very good impression of a spectator at a tennis match.

'Hang on,' he said. 'Was that text from who I think it was from?'

'Yes,' Sherlock said, still smiling, 'But I think that she might have met her match.'

Kate texted back: 'He's already eaten, thanks,' handed the phone back to Sherlock, and calmly continued to eat her dinner.

Pause, then the noise again. 'I am so going to have to change that,' Kate said grimly.

Sherlock held up the phone to her so she could read the reply.

'Who is this?'

Sighing she took the phone back and texted: 'Kate Watson. Things have changed.'

'Interesting,' came the reply, then nothing.

'Right,' Kate said, and with a level of technical knowledge that she had kept very well hidden until now, changed the text alert noise for that number to a less suggestive one.

'What?' she asked John, who looked as if he badly wanted to say something, but wasn't quite sure how to phrase it.

'Nothing,' he said. Then looked at Sherlock, who was still wearing an expression of poorly concealed amusement.

'Oh please,' Kate said. 'Do you really think that I'm threatened by her? She may be very clever and very good at manipulating men, and women for that matter, but I bet she couldn't crack a chest or deal with six testosterone driven men at a trauma call.'

'Former no, latter almost certainly', John said contemplatively.

'What is it about this woman that reduces men to drooling idiots?' Kate asked, exasperated at John's expression.

'I'm not a drooling idiot,' John said, pretending to be offended.

'Not normally, no.' Kate said dryly.

Three days later a visitor turned up at the lab.

'Hello Irene,' Sherlock said, not looking up from the microscope.

'Hello yourself,' she said. 'Who's Kate?' No preamble then.

'Last time I saw you, you were about to be beheaded by Al Qaeda. You could at least say thank you before you start interrogating me.'

'Thank you.'

'You're welcome. And you know exactly who Kate is.'

'Sherlock Holmes. I never thought that I would see you domesticated.'

'You make me sound like a cat. I'm not domesticated.'

'Aren't you?' she said dryly. He looked different she realised. Calmer, happier somehow, more sure of who he was.

'Is there a reason for this visit, Irene, or is it just that you can't bear to admit that I might have chosen another woman when I could have had you?'

'I need your help,' she said reluctantly, 'although I have to confess that I would also dearly love to meet the woman who has converted you to domestic bliss. I appear to have found myself in a spot of trouble, and I think you might be just the man to get me out of it. Of course if its going to cause tension for you, then I can ask someone else.'

'Why would it cause tension?' Sherlock said, oblivious as always. 'Its not as if we ever had anything other than a professional relationship, Irene, unless there's something that I'm missing.'

'Nothing at all,' she said softly, shaking her head, wondering yet again why her charms seemed to have no effect on him.

She had just finished explaining the situation to Sherlock, when they heard voices in the corridor outside. John and Kate came in, laughing and carrying the lunch they had gone out to buy.

John stopped dead, looking as if he had seen a ghost. 'Hello John, dear,' Irene said, giving him a lingering kiss on the cheek. 'Surprised to see me?'

'And you must be Kate,' she said, without waiting for John's stunned response.

'Irene Adler, I presume.' Kate said cooly. 'In trouble again and after Sherlock's help? No wait,' she considered, 'a challenge, I think, something you want rather than something you need.' Sherlock looked at her in question, and she shook her head at him, almost imperceptibly. Not a no, but a not now. An 'I'll tell you later' Irene realised. But what, she wondered had been the question. Something that Kate knew, that he didn't. Now there was a first.

Irene Adler was surprised about three things, all within the space of two minutes. It was a long time since anybody had had that effect on her. First, she noted that Kate Watson was undeniably beautiful, not in the manicured, perfectly made-up way that Irene was. She was beautiful in that frustrating, 'I've just pulled on whatever I found at the bottom of my wardrobe and I still look stunning in it' kind of way. Second, Kate Watson was clever, not just clever but brilliant. Thirdly, Sherlock Holmes was absolutely and completely in love with her. This was not challenge, this was defeat, and both of them knew it.

She did the only thing that she possibly good under the circumstances. She shook hands with Kate and murmured, 'Game, set and match?'

'I think so,' Kate said, finding to her surprise that she rather liked this woman, who took on men and won. Who knew when she was beaten. Then they both started laughing and Sherlock and John looked at them both in amazement.

'I think we've confused the boys,' Irene said. 'One day, Kate Watson, you will have to tell me how you managed it, but today we have more pressing matters to attend to.'

'You're not threated by me,' Irene said later when they both found themselves watching John and Sherlock arguing over something Sherlock had found on the computer.

'Should I be?'

'Most women are.'

'Ah' said Kate, 'but I am not most women.'

'Obviously not.'

'Tell me.'

Kate didn't have to ask her what she meant. She considered for a moment, and then said, 'I'm not sure I can. You see, I didn't pursue him, Irene, he pursued me. He was the one who persuaded me that we should have a relationship.' She watched him work, so brilliant, so passionate, so Sherlock.

Irene shook her head, 'Too simple,' she said, 'for a man that complex. It wasn't just the thrill of the chase, was it? What was it about you that made him pursue you?'

'Acceptance, I think,' Kate said, wondering why she was telling her this.'He's spent his whole life trying to hide who and what he is, trying to fit in despite it, or trying not to care that he didn't fit in. I knew exactly who he was, and I didn't judge him or try to change him. Turns out that was all it took.'

'I wouldn't have tried to change him,' Irene said.

'Yes you would,' Kate laughed.