Kate woke up suddenly, heart racing. She glanced at the old fashioned alarm clock on the bedside table. 2am. Still night then. Quietly, she got up and went into the kitchen to get a glass of water. Unable to shake off the dream or the feeling of panic, she made herself a cup of tea instead, and sat at the kitchen table, trying to work out why she should have had the dream again now, after all this time. Head in hands she tried to dissect it out, how much was memory, and how much imagination. There had been a sense of impending doom which she had never felt before. In the past she had always woken up with relief, knowing that it was all over, that it couldn't happen again, that she was safe. Tonight the dream still felt very real, very possible. A hand on her shoulder made her jump.

'Are you okay?' He asked. 'Bad dream?'

She smiled up at Sherlock, who came to sit next to her. 'Yes, sorry. I didn't mean to wake you.'

He shook his head. 'Its fine, I wondered where you'd gone. David?'

'Yes, how did you know?'

'Its the only thing I can think of that would have this effect on you.'

Kate rubbed the back of her neck. 'Its crazy, isn't it? He's not even in the country, and he still has this effect on me, after all this time.'

Sherlock quietly got up and put his arms around her from behind. She rested her head back into his chest. 'Its not crazy at all Kate. You were terrified of him. The question is, why now?'

'Thats what I've been trying to work out. Maybe because I've been so happy, perhaps my subconscious is somehow coming up with a form of revenge. Maybe I'm worried that its all going to happen again - no, I know', she said, not having to look at him to feel his concern. 'I know that it isn't, truly. I trust you, and I know that you're a million miles away from the man that David was.' She turned to look at him, and he kissed her gently on the forehead, the way you would kiss a child.

'Come and sit on the sofa with me' he said, inclining his head towards it. He arranged her next to him, his arms around her, so her head was resting against his shoulder. 'Better?'

'A little.'

'Kate, I am not David. Irrespective of what the majority of people may think about me, I could never treat anybody the way that he treated you.'

'Sherlock, I know that. I don't think thats why I had the dream.'

'Nor do I, but I don't think that its your subconscious coming up to bite you either.'

'You have a theory?'

'Yes, but you're not going to like it.' He paused, then said slowly 'Kate, how long ago did David go to Hong Kong?'

'Probably eighteen months ago now, why?' He remained silent, waiting for her to work it out. 'Oh God, you think that he might have had a fixed term contract, that he might have come back?'

'Its a possibility. Banks usually work in contracts of one to two years. You know that, maybe your subconscious does too. For the first year you knew you were safe, but as time goes on, I think that you're waiting to see him round every corner.'

'You're right.' Kate pulled away from him slightly, and turned to look at him properly, surprised as always at the level of his insight. 'A couple of days ago, I thought I saw him coming up the escalator at the tube on the way to work. I'd forgotten. It wasn't him, and I knew he was in Hong Kong, but for a split second I wondered if he could have come back.'

'Precisely, and its been sitting in the back of your head, waiting to come out. The realisation that he could come back.'

Kate sat and contemplated for a while. 'Can you find out where he is?'

'Of course. I'll get onto it first thing in the morning. But Kate,' he paused, struggling to phrase his next question.

'Yes, I want to know', she said pre-empting him 'I would rather know.' Then very quietly 'Do you really think that he would be stupid enough to come and find me, after all this time?'

'I would,' he said. 'If I was him, I wouldn't be able to let you go either. I cant predict exactly how his twisted little mind works, I've never even met the man, but if I was him I would come and find you and try to persuade you to have me back. I suspect he would tell you that he's changed, that he realises what he's lost, that he misses you, that he wants a second chance.'

Horrified, Kate stared at him 'After all this time and after everything he did. You really think he would imagine that I would even consider it?'

'He is not a normal man, Kate. From what you've told me he probably hits the criteria for psychopathic personality disorder; a little under one percent of the population does after all. He does not sound like a man with normal emotions, or normal thought processes. He has an over-inflated sense of self-worth. He would probably believe that he has a chance of getting you back. Somewhere in your subconscious you know that he will try to get you back if he comes back to London.'

Kate shook her head 'I cant think about this now. I want to believe that he's still in Hong Kong, but I need to know that.'

'And if he isn't?'

'Then at least I'll know. Would the restraining order still be in effect?'

'I would imagine so, I'll check with Lestrade in the morning.'

They sat in silence for a long time, Sherlock formulating plans for investigating David's whereabouts, Kate wondering what on earth she would do if he tried to come back into her life.

...

Kate came out of the shower the next morning to find Sherlock uncharacteristically up and dressed. 'Why are you up so early?' she asked, surprised.

'I thought I'd walk you to work.' he said. 'After last night I thought you might appreciate the company.' He pushed a cup of coffee across the table to her.

'Thank you' she said quietly, smiling at him.

'Its not entirely selfless you know,' he said. 'Until I know that bastard is safely on the other side of the world I don't want you walking around on your own.'

'What realistically could he do to me?' she asked quietly.

He hesitated for a fraction too long and she looked up at him sharply 'You're actually worried about this aren't you? Sherlock, it was just a dream.'

'I know, but it remains a possibility. As to what he could do to you, I honestly don't want to think about it at the moment. I just want to keep you safe.'

They spoke little on the journey to work, each lost in their own thoughts. Kate gave him as many details as she could about David; place of birth, date of birth, education, previous jobs, everything and anything that could help him to track him down. He hugged her a little more tightly than normal as he said goodbye to her outside the ambulance doors, and watched her go in when he would normally have turned away before she got inside the doors. Kate was split between being touched at his concern, and worried that his concern always had a rational basis. If Sherlock was worried, then maybe she should be too.

...

Fortunately work was busy that morning. She barely had time to hang up her coat before she was called into resus for a cardiac arrest, then a trauma call, then a sick child. The morning passed with little time to think about David, and she was still thinking about the morning's patients as she went to the canteen to get a sandwich for lunch. As she walked back through the seating area she heard a voice call her name, and her blood went cold. He was sitting a few feet from where she stood. He looked tanned, relaxed, pleased to see her. Definitely David, definitely not in Hong Kong.

'Kate', he said again 'Why don't you come and join me?'

She shook her head in disbelief 'I don't think so, do you?'

'Its been over eighteen months Kate. I'm not the same person that I was back then. Won't you at least give me a chance to explain, to apologise?' In the back of her head, Kate heard Sherlocks voice from last night saying: ' He would tell you that he's changed, that he realises what he's lost, that he misses you, that he wants a second chance.'

Warily, Kate say down, her sandwich and coffee left untouched on the table in front of her.

'How are you?' he asked politely.

'Fine' she replied.

'Are you seeing anybody?'

'I don't think thats any of your business, do you?'

'I just want you to be happy, Kate.' She looked at him in disbelief. This was the man who had made her life a misery for the best part of two years. The man she had been terrified of. He looked so normal, so unthreatening, sitting here.

'I am happy,' she replied, probably a little too quickly.

'I wanted to apologise for my behaviour. I was - upset, about the baby. Its no excuse, but I wanted you to know that if you gave me another chance I would never, ever treat you like that again.'

She looked at him in amazement. 'You aren't serious? After all thats happened, you really think that I would give you a second chance?'

'I told you, I've changed.' He looked innocent, hopeful even. 'Please, Kate, come out to dinner with me, for old times sake at least, let me show you how different things are now.'

'You're crazy, David. No, thank you. I don't want to go out for dinner with you. I just want you to stay away from me.'

'You're seeing someone else, aren't you.'

'Thats irrelevant.' Kate was becoming angry now, and anger made her say. 'But yes, since you ask, I am.'

'Who is he?' David sounded mild, calm even.

'Its none of your business.'

'Because I heard that you were seeing some private investigator chap.'

Kate got up. 'I'm not discussing my relationship with you, David. Stay away from me, or I'll call the police.'

As she got up to leave he shot an arm out and grabbed her wrist, preventing her from walking away. Suddenly she was paralysed with fear. She stood, staring in disbelief at his fingers around her wrist. She could feel her heart racing and the sweat collecting at the back of her neck.

'Coming back to the Department, Kate?' asked a bright voice behind her. Alice. Thank God. 'SHO teaching starts in five minutes remember, don't want to be late.' Kate kept staring at Davids hand around her wrist. Reluctantly he let go, and she let Alice steer her out of the canteen, leaving her untouched sandwich and coffee on the table.

'I saw,' Alice said quietly, as they walked back to the Department. 'I saw the whole thing, thats why I came to rescue you. Bastard, what on earth is he doing back?'

Kate shook her head. She knew that she was a hairsbreadth from falling apart, and didn't want to do it in the middle of the hospital corridor. 'We need to call security' she said to Alice, 'he shouldn't be here.'

'Lets just get back to the Department first.'

...

They reached Kate's office safely. Alan, the head of security was down within minutes. He was only too aware of the problems that Kate had had with David after they had broken up. They were checking cctv, but David certainly wasn't in the canteen any longer. Five minutes later the cameras showed him leaving the hospital and heading towards the tube station.

Kate's phone buzzed, text from Sherlock. 'Sacked from Hong-Kong job 2 months ago. Current whereabouts unknown, doing some investigating.' She showed Alice.

'Phone him,' said Alice. 'You're not in a fit state to work.' Kate looked at her hands. They were still shaking.

'Safer for you to not be here' Alan said. 'He knows where to come to look. I'll phone the police and let them know what's happened. They'll need to talk to you.'

Kate sat at her desk, immobile. Alice silently held out her hand for her phone, then when Sherlock answered, handed it back to Kate. 'Kate, whats happened?'

'David,' she said, trying not to cry. 'He was here.'

'I'll be there in ten minutes.'

'No, Sherlock, its fine, I..'

'No, its not fine. Kate you don't know what he's been up to in Hong Kong. Stay exactly where you are. Have you told security?'

'They're here.'

'Let me talk to them.'

She handed the phone over to Alan who listened intently for a minute, then took the phone outside to talk to Sherlock. He looked grave when he walked back in. 'Don't go back into the Department, Kate,' he said. 'You're safer in here. I'll get one of the boys to come and wait with you until your boyfriend gets here. He sounds as if he can handle himself. I need to go and talk to the police.'

Ten minutes later Sherlock arrived and hugged her tightly. 'Thank God you're okay'. Alice waved from behind his back and silently let herself out of the office, taking the security guard with her.

'Tell me.'

He shook his head. 'Not here, lets get you home, its safer there. John has contacted Lestrade and they'll both meet us there.'

'Sherlock, what have you found out? Did David do something in Hong Kong?'

'Yes.' He shot her a look that was both concerned and calculating. She hated it when he couldn't work out how to tell her something. It generally meant something bad was coming, and that his intellect was conflicting with his newfound concern for her emotions. Rational decisions he could make in a split second, emotional ones took him a lot longer.

Kate's legs suddenly felt as if they were made of jelly and she sat down quickly on her chair before they gave out entirely. 'It happened again, didn't it? He attacked somebody else, another woman?'

'Yes.'

'Is she still alive?'

'Yes, but more through luck than judgement on his part.'

'And now you think that he's going to come after me.'

'It seems likely, yes. Kate, we need to get you home. I can keep you safe there. Come on, lets go.'