"Are we nearly there yet?"

"Of course not. We only left ten minutes ago."

"It seems like ten years."

"Yes, I know exactly how you feel."

"Six hours and fifty minutes to go. Seven hours, stuck in a car with you. I must have been insane to agree to this. Assuming we don't kill each other, and that I manage to sustain consciousness despite the overwhelming stench of your cologne, what shall we do for the next six hours and forty-nine minutes?"

"Personally, I have paperwork to catch up on."

"Boring. What am I supposed to do while you're weaving your intricate, deadly webs of international espionage?"

"Intricate and deadly is right; I'm reviewing the departmental budget. Can't you read a book or something? You can use my tablet computer if you like."

"I've read them all."

"You've read every book in the world? Impressive. How were they? Do you have a favourite?"

"I've read all the important ones. I'm not like you; I don't fill my mind palace with any old nonsense and rubbish. No wonder it took you so long to learn Serbian - the vocabulary probably got lost amidst dialogue from 1970s bodice-rippers and extracts from 'Which Despot?' magazine."

"I do not read bodice rippers. You're confusing me with your landlady again."

"Yes, you did read them. When we were stuck in that caravan in Brighton for a week."

"Well, Mummy and Daddy were off doing outdoorsy things all day, and those Mills and Boon novels were the only books in the place."

"And you felt the need to traumatise me by reading them aloud as bedtime stories. When I was five."

"They were hardly hardcore pornography; everybody's knickers stayed on and the orgasms were euphemistic. Please don't try to put the blame on me for your plethora of neuroses. You were always a peculiar child; it had nothing to do with me."

"It had everything to do with you! You instigated your subtle campaign of terror against me as soon as I was born."

"Pure self-defence. You spent the first six months of your life filling the house with ungodly shrieking. I would have finished prep school two years early instead of one if not for your inhuman decibels."

"Infants scream. It's normal."

"Not to that degree. Our housekeeper at the time was convinced you were possessed. She took to hanging crucifixes on the wall above your cot, and flicking you with holy water when Mummy wasn't looking."

"Yes, I do seem to remember waking up to find my mouth full of garlic on one occasion. I suppose you encouraged her in this mindless superstition."

"Well, it was quite amusing. You were an inordinately demanding child, you know, and you haven't changed much; I haven't had a proper night's sleep since you were born. The first few months were certainly the worst as regards volume, however."

"...and you believed a proportionate response to this was to encase me in plastic."

"I did not encase you in plastic! I constructed a comfortable sound-proofed playpen, suitably tailored to your size."

"I almost suffocated. Mummy had apoplexy."

"The design incorporated a ventilation system - it was hardly my fault you weren't bright enough to work out how to use it."

"How is a two-month-old supposed to know what to do with a snorkel?"

"It wasn't difficult - you had merely to put your mouth around it and suck."

"Easy for you to say. You knew all about that by the time you were fifteen, didn't you? I'll never forget what I saw in the toolshed during the summer holidays that year. Though if you were putting into practice what you had learned from those disgusting books, I expect your early partners were sadly disappointed, not to mention profoundly confused as to your gender identity. Then again, weren't we all."

"There's no need to be spiteful, little brother. Jealousy is such an ugly thing. I can't help it if my intellectual prowess resulted in natural carnal curiosity at a precocious age; whereas you, by contrast, are still proclaiming - at thirty-five! - that girls are nasty and have nits."

"I was never jealous of you in that department, believe me. My restraint has nothing to do with lack of opportunity. For your information, I received plenty of offers when I was fifteen. A great deal more than you, anyway."

"Oh? You think so?"

"It seems a safe assumption, given our respective appearances."

"Now you're being petty."

"Not at all; merely truthful. In my teens I was repeatedly informed by reliable sources that I was strikingly handsome, with a captivating physique. You, on the other hand...do you remember your Byronic phase, when you were seventeen? You went around for six months looking like a ginger Meatloaf."

"For the record, Mummy and Grandmere do not count as 'reliable sources' in this context, and furthermore, I am not 'ginger'."

"You're not now. At least you've developed a more restrained sense of fashion to go with the hair dye - black is so slimming, isn't it?"

"So are opiates, I understand."

"Boring! You. Are. So. Boring. Even your insults are dull. Unimaginative. How am I going to survive for the next six hours and thirty-seven minutes?"

"Continue in this vein, brother mine, and such concerns will cease to be relevant."

"Oh, wonderfully subtle. Death threats. Even more boring."

"Not at all. I wouldn't dream of killing you on Mummy's birthday. I was contemplating chloroforming you; the only drawback is you'd probably enjoy it."

"Anything would be preferable to listening to your pompous voice prattling on and on ad nauseum. Why are we doing this? We never do this. Travel together. Not since that time Lestrade for some reason gave us a lift somewhere in the back of his car. You were being ridiculously supercilious and dull on that occasion, as well. And wet. And smelly. Why were you wet and smelly?"

"He wasn't giving us a lift, witless child. He was arresting you. I'm not surprised you don't remember; you collapsed in the police station half an hour later and spent a week in hospital."

"Oh, yes. So I did. And you were wet and smelly because..."

"You had been sick all over me. It happened rather a lot in those days, didn't it?"

"So? You were sick over me once."

"That was only after you poisoned me for a joke."

"An utter lie. It wasn't a joke; it was an experiment."

"An experiment to see whether you could get away with fratricide?"

"How was I to know you had lost eighteen pounds since the last time I'd seen you? The dosage was off. The effect was significantly more profound than I'd intended. Besides, I apologised."

"You did not apologise. You told me it was my own fault for being unable to resist a second slice of cake."

"It was. You were supposed to be on a diet."

"It was my birthday. And I've been unable to look at chocolate fudge cake without feeling sick ever since."

"...which was the whole point of the experiment. Single-exposure conditioning. And it worked, so stop complaining. It was a much better present than socks. Speaking of which, what did we get for Mummy this year?"

"'We' are giving her a sapphire necklace and matching earrings."

"How dull."

"Brat. She likes sapphires. They're her birthstone."

"Making it an obvious and uninspired choice of gift."

"Well, get her something yourself, then, if you find my taste so dreadful."

"Fine. I shall."

"And when will you accomplish this, given we're arriving half an hour before her party starts and all the shops will be closed?"

"Well, I suppose there's...this."

"Where on earth did you get that!?"

"Bart's. It was for a case, but I'm finished with it now."

"What was it doing in your pocket, for goodness' sake? It hardly seems hygienic."

"I must have picked it up instead of my phone when we left. You were rushing me. And now I don't have my phone. We need to go back for it."

"We bloody well do not. We're late as it is."

"What if I need to call John?"

"I'm sure your ego can survive without him whispering sweet nothings in your ear for one evening. Now do get rid of that...item. I don't like having it in the car. There's something unnatural about it; it can't possibly have come from a normally-developed man. Why is it all shrivelled up like that?"

"Monkey glands. Quite an interesting side effect. Mummy collects medical esoterica, and this is a unique specimen; somebody offered me a thousand pounds for it on Ebay."

"She collects antique medical instruments. You can't give her a...one of those...for her birthday, revolting boy. She'd have a fit. Dispose of it at once."

"Oh, all right. If it'll stop you nagging."

"Well don't just toss it out of the window, for heaven's sake!"

"What am I supposed to do with it, then?"

"Perhaps we should give it a decent burial at the next suitable spot. I'm beginning to think you were right, by the way. Sharing a car was a terrible idea. I could have finished my paperwork by now if you weren't here. Instead I'm going to be spending the next twenty minutes standing at the edge of the hard shoulder with a shovel, performing last rites for a..."

"One of those."

"Yes."

"It could have been worse."

"How?"

"If you'd picked me up yesterday, there would have been two of those."

"I can't understand it!"

"Well, obviously they didn't both come from the same corpse."

"No no no, I mean I can't understand why you do things like this. Carrying body parts around in your pockets. Coming down from Oxford without a real degree. Playing detective. Living in that cesspit in Baker Street with a man who pines for you constantly, despite emphatically declaring his heterosexuality to every passer-by. What are you trying to prove?"

"What are you trying to prove?"

"I beg your pardon?"

"Remembering birthdays. Giving people normal, boring gifts. Dressing like a bank manager. Serving the realm or whatever it is you think you do. What's the point? Laws don't apply to people like us, social conventions even less. I know you don't care about them, so why do you pretend they matter?"

"Because other people care. I play the game in order to get on in life; do something meaningful."

"I don't follow the rules, and I get on in life. I'm famous."

"Yes, for wearing a ridiculous hat and carrying people's unmentionable parts around in your jacket. You're not a success, little brother; you're a fad. A sideshow. The media attention, the adulation...it all comes down to the fascination ordinary people invariably have for a freak. You are the modern equivalent of a bearded lady. It may seem like they admire you, even love you - they don't. These people are making a mockery of you, and you permit it because you want so desperately to be special."

"...sod off."

"Now who's being unimaginative?"

"You're jealous."

"Of your funny little hobby? Oh, come on. You can't really believe that. I could do what you do in my sleep. I could do anything you do in my sleep. You know that. It's probably why you chose to do something with your life that you knew I would find utterly pointless - to avoid competing with me, and losing, the way you always did when we were children."

"I never said you were jealous of my deductive powers. I freely admit your intellectual superiority."

"Of what, precisely, am I supposed to be so jealous, then? The ear-hat? It's called a deerstalker, incidentally."

"I know what it's called. Incidentally, you're jealous because despite your attempts to turn me into a soulless automaton programmed solely to keep you company, I have initiated and maintained a meaningful relationship with someone who possesses actual feelings."

"That's absurd. If your relationship with Dr. Watson fulfils some mysterious need, and keeps you away from intemperate habits, I'm very happy for you, but I assure you I myself have no need for that kind of companionship. There's nothing wrong with enjoying one's own company."

"Except that too much of it will make you go blind. I hadn't finished, however."

"What then?"

"Against the odds, I have a true friend; somebody I trust implicitly, somebody who would give his life for me, and I for him. Somebody who accepts me for who I am while simultaneously challenging me to be a better man; brings out the best in me; makes me a whole, living, feeling human being in a way I never believed possible, let alone desirable, before."

"And this would upset me - as opposed to merely making me nauseous when you go on about it - because?"

"Because that companion could never be you. I suppose you thought you were helping me by encouraging me to be cold and disconnected from the world, because you had no point of reference to do anything else. I must have seemed as broken to you when I was younger as you seem to me now. I understand it must be difficult for you to accept that I am not, have never been, the same as you. Given that quite certainly nobody else even comes close, then despite your protestations the only logical conclusion is that you must be extraordinarily..."

"Shut up."

"Oh dear. Have I touched a nerve by pointing out that by your very nature, it's impossible for you ever to experience a genuine human connection?"

"Shut up or I will put you out of this car and you can bloody walk the last two hundred miles."

"...or is it that you honestly believed you had a real connection with me? Did you actually believe our absurd facsimile of a relationship could be remotely satisfying on my side, that I thought of you as anything other than my jailer? You tried to control me; all my life, you made me lock away the very things John brings out in me. You damaged me in ways I can't even begin to describe, and the worst of it is, you did it all while making me feel inadequate for not meeting your standards of emotional repression, as if being a cold, soulless bastard represented the pinnacle of enlightenment. And I'll tell you something else - I can forgive you for it, at least to some extent, because I now believe you did it not out of malice, but because you were so profoundly lonely. The tin man wanted a tin friend instead of a heart. I understand this mainly because of John, because of the things he helped me learn about people. Ironically, the man who took me away from you is the only reason I still bother talking to you - now I can afford to pay my own rent."

"It's been four hours. I'm bored. Say something. Even if it's threatening to throw me out of the car again."

"There would be little point - we're arriving in a few minutes."

"Damn - I forgot to get Mummy a card."

"I signed it from both of us - naturally, being as I'm a heartless, emotionally challenged control freak with an incongruous sense of filial duty."

"Well, you are."

"Quite."

"...you're aware I was trying to goad you into a fight because I was so hideously bored?"

"Yes, you seem to have spent much of your life doing that."

"Why didn't you?"

"What?"

"Fight back. Bear in mind that you started it by referring to me as a fairground attraction."

"I said that because I was trying to goad you into a fight because I was hideously bored."

"Touché. So you stopped playing because you lost?"

"No, I stopped playing because for once, you had actually managed to hurt those feelings I'm not supposed to have."

"Don't expect an apology."

"I never do."

"Although I am."

"You are...what?"

"I didn't hear that."

"Sorry! All right? I am sorry."

"What was that tremendous, apocalpytic cracking sound? I think it was hell freezing over because you apologised for calling me a callous bastard."

"Soulless bastard. Soulless bastard who made my childhood a breeding ground for mental health issues in later life. At seven years old you were already the classic refrigerator parent. Thank God you don't have any real children. And I was not apologising for saying it - I was apologising for implying that I minded."

"In that case, I apologise as well."

"For calling me a bearded lady and claiming I ruined your life?"

"No - for implying that I minded."

"What are you doing now?"

"Texting John. I just won our bet. He owes me two weeks' worth of washing up duties."

"Hardly a victory, as you never do any washing up. I thought you said you left your phone behind when you picked up that...item?"

"No, I brought that with me as a prop to help me embarrass and frustrate you as much as possible. It is a real one of those, though."

"I should hope so, after I spent ten minutes giving it last rites in a ditch off the hard shoulder. What was the bet?"

"That I could make you apologise to me for being such a rubbish brother by the time we got to Mummy's."

"I see. Charming. I'm not sure it counts, however - you apologised first."

"There was nothing in the rules to say I couldn't."

"And it didn't occur to you that there might be an easier way to do this than instigating mutual emotional abuse?"

"You instigated it. Is there another way?"

"...probably not, no."