Greg Lestrade was lifting his hand to knock on the door of 221B Baker Street, London, when a bustle of floral prints and the out-of-character scent of 'Arabian Nights' perfume assaulted his senses. Mrs Hudson looked up at him, surprised, and said, 'Oh, hello, dear. The boys are right upstairs, if you want to see them. Sorry, I can't stay… I have a train to catch.'

'Thanks, Mrs Hudson. See you later.'

'Later, dearie,' and she patted him fondly on the arm then walked off quickly.

Greg pushed the open door and walked in, then started up the stairs. He could hear Sherlock's voice, and the low tones of John saying something, and he was just about to call out to them when Sherlock said, in a loud voice, 'Oh, God, John, you're a machine!'

Greg froze, but only for a moment, then turned and tiptoed back down the stairs, and opened the door very quietly. He was obviously not quiet enough though, for just as he turned to cross the footpath to his car Sherlock's voice sounded from above him, 'Lestrade, what on Earth are you doing tiptoeing about my flat? Do you have a case for me? If so, I would suggest you come back up here at once!'

Greg opened his mouth, shut it, then said, 'Right, Sherlock. Hi. You'll have to let me back in, then.'

'John!' called Sherlock, and Greg walked back to the door and waited.

John Watson opened the door for him and gave him a quizzical look, 'Everything okay?' He was fully dressed and looked quite… relaxed. He was certainly not half-naked and still aroused, which Greg had been steeling himself to see. Greg nodded, confused.

'Hi, John. Ah, yeah, I forgot my… never mind.'

Sherlock peered down the stairs past John and leapt down to stare intently at Lestrade, then smiled, 'You heard me. You heard what I said to John.'

'Look, Sherlock, I don't care… I mean, that sort of thing, it's between… well….'

"Don't be ridiculous, Lestrade, I know you won't break confidence. Not on John, anyway.'

"God, Sherlock, it's not that. It's just what… people don't talk to each other about these sort of things,' Greg felt himself blushing, and looked at John Watson for backup, 'Right?'

John just frowned at him, then looked hopefully to Sherlock for clarification.

Sherlock said, 'They don't? But John's… he's… remarkable! Why shouldn't I want to tell you about that?'

'Shut up, Sherlock, just shut up about it!' snapped Greg, feeling the blush spread to his neck, 'I don't want to hear another word about it, and I would strongly suggest you don't go talking to anyone else about it, alright?'

He pushed past a nonplussed Sherlock and a half-grinning John, and walked up the stairs, 'I have a case for you, remember?'

Sherlock blinked and looked hopefully at John, but John just shook his head and smiled and followed Lestrade up the stairs, 'We'd better do as he says, Sherlock.'

Sherlock frowned, but followed them meekly.

Lestrade sat down, to his gratitude being offered a cup of tea for once by John, 'Kettle's just boiled.'

'Well, coffee if you don't mind, John. I've got time for once.'

John brought a huge red mug of coffee out and sat down next to Lestrade on the couch, facing Sherlock.

'Thanks.'

'Well sir, the details. Cold case?' Sherlock asked.

'How the devil did you know that?

'Quite simple, you just practically told me, 'I've got time for once,' also it's a Tuesday, quiet day on the murder scene usually, so you would have been checking over your cold cases for something to do. Am I wrong?'

'Oh, well, of course not, you're never wrong…' Greg's voice faded as Sherlock sat up abruptly, then leaned across and tapped John firmly on the nose. John just stared blankly at Sherlock.

'What the devil are you doing?' asked Greg.

'You didn't blink,' Sherlock accused John, then reached across and tapped Greg on the nose.

Greg flinched and said, 'Sherlock, will you piss off! What the hell are you up to?'

'He didn't blink,' said Sherlock smugly, then looked abruptly impatient with himself, 'Three months! Three months, it took me, to notice. By God, you are good, John. Tell Mycroft I said you'd pass.'

John stared at Sherlock, looking suddenly a little lost. Greg frowned, 'What?'

'Off you go then, go talk to Mycroft. I suppose he's asked you for a debriefing at this point?' said Sherlock dismissively to John, who nodded mutely. Sherlock's lips pursed, 'In that case, I expect he won't be sending you back at all. I'm sure he'll have better uses for you, now that he knows just how long you can stand up under scrutiny,' Sherlock's tone was light and amused, but to Greg it sounded a little forced. No, strike that… very forced.

John looked at the floor, and Greg said, 'Wait, WHAT? Sherlock, what the hell are you playing at?'

John stood, his movements looking oddly heavy, and walked towards the door.

'You heartless bastard, Sherlock!' exclaimed Greg, 'John, wait!'

'Oh, I'm not the heartless one,' smiled Sherlock coldly, 'Am I, John?'

John took one more look at Sherlock and walked down the stairs.

Greg jumped up and said, 'John, wait!' and ran after him, taking the stairs two at a time. He stopped John at the door and said, 'What the hell is going on? What, he's had you, and now he's throwing you out? Is that what this is?'

'Had me?' asked John, and Greg's heart went out to the other man when he saw the infinite sadness in those too-blue eyes.

'I heard you two, you know…' Greg hesitated, then braved on, 'Earlier, when you were… you know. I heard him call you a machine.'

'When we were what?'

'Oh, don't make me say it.'

'Then I will,' came Sherlock's voice from above them. Greg looked up to see Sherlock standing at the top of the stairs, 'He heard me call you a machine, John, and assumed we were engaged in sexual intercourse. Of course, under the circumstances, there was no reason for Lestrade to jump to any other conclusion. What took me three months to deduce, will probably take him a lifetime. Although, perhaps not your lifetime. What is it, anyway? A century or two? Three? Five?'

'Undetermined,' whispered John, and would have left, but Greg's hand was on his arm and he stayed where he was.

'I'd let him go, Lestrade, if he decides to move anyway you will end up with a shattered wrist,' warned Sherlock.

'Jesus Christ, can one of you tell me what the hell is going on here?' demanded Greg.

Sherlock rolled his eyes, 'I already did, Lestrade, twice. He's a machine. A machine sent by Mycroft to be my minder, when he found you couldn't keep up.'

'A machine? A killing machine? A mercenary?' asked Greg dubiously.

Sherlock's exasperation seemed to know no bounds, 'No! A MACHINE. What, are you stupid? Oh, sorry, yes. An android, a robot. A robot minder, courtesy of my big brother.'

Greg's hand fell from John's arm and he stared at them both in stupefied surprise. Eventually he found his voice, but addressed John instead of Sherlock, 'John, how long has he been delusional like this? Have you been hiding it from Mycroft?'

'Oh, for….' Sherlock huffed in disgust and disappeared back through the door.

Greg turned to John, who was looking up the stairs.

'John?'

John took a long time to answer, then said quietly, 'He's right.'

And he turned the too-blue eyes to Greg. Greg stared at John, wondering if he was going to have both Sherlock and John committed. But then the eyes looking at Greg changed. The dark blue irised out and behind it was…. Greg felt sick to his stomach. Behind the blue irises of John's eyes were another set of irises… silver and mechanical with overlapping leaves.

'Oh, Christ,' he breathed, feeling light-headed, 'You're a robot?'

John nodded sadly.

'Wait a minute,' floundered Greg, 'You're an emotional robot? You have feelings?'

'Oh. Yes, quite strongly programmed for them,' sighed John, 'Helps with the disguise, you see.'

Greg closed his eyes, 'Damn. And they put you with Sherlock? That's harsh.'

'Not really,' responded John, 'Who would notice that I was a machine, next to him?'

'You were too perfect,' realised Greg, looking at John with new comprehension, 'Perfectly compassionate, perfectly ethical, always noticing other people's feelings and being there for them. I should have noticed.'

John nodded sadly, and Greg asked, 'But do you really feel all those things, John? Or is it all…'

'Just programming,' said John, but Greg Lestrade frowned and tilted his head as John looked back up to the top of the stairs with ineffable sadness on its face.

'I have to report back to Mycroft,' said John, and was gone. Greg stood at the bottom of the stairs for a long time, then looked up the stairs and slowly plodded back up. The cold case could wait. Somebody had to keep an eye on Sherlock, now that John was gone. It was an easy role for Greg to slip back into.

He walked back into the silent flat. Sherlock was standing at the window, watching John get into a cab below. Greg walked quietly up beside him, and they both stood there until the cab drove off. Sherlock turned away and said, 'Just go.'

'No, I'll stay the night,' said Greg, staring at the back of Sherlock's head.

There was a long, long silence, then Sherlock whispered, 'Thank you,' and walked away into his room.