A/N: I had some more lab rat plot lurking about. They're much too cute. (And I had no better ideas. Too much work, here in real life, I'm drained. I'll try something cleverer next time.) -csf


.

In the dark familiar bedroom I wake up with a start. Before I check myself my hand already roams under my pillow for my service gun. I shake my head to disperse some of the confusion, wondering what triggered the cold sweats and rapid shallow breathing this time.

Sherlock is a likely cause. Sometimes he wakes me with explosions from his expanded chemistry set. Other times he's practising indoor shooting (safely wearing ear defenders and aiming at a black silhouette paper target). There's the odd event where the fire alarm blares suddenly and as I reach the downstairs landing Sherlock has already concealed the cause of the commotion; and he won't ever tell me.

When the insomniac detective exquisitely flows through Bach's symphonies, though, that's the one occasion I don't wake up; no matter how badly I've been sleeping of late. Mrs Hudson will tell me all about it in the morning, as she laments the ungodly hours her tenant gets up to playing the violin.

Tonight it's something else entirely.

There's a droning, persistent noise drifting through the stairwell. Anxiety taking over my senses now, I get up summarily and lower my bare feet to the cold wooden floor. I pad across the room virtually silently, but not before I grab my gun anyway, as an afterthought. Better take precautions. Nothing is granted in Baker Street. I hear no intruder fight noise, no daring robber or avenging murderer by proxy. No Mycroft Holmes – he will visit at odd hours as easily as in broad daylight, proving that insomniac streak runs in the family. Or maybe just to convince me he's not a vampire in disguise. I wouldn't put it past Mycroft, he does love to be dramatic.

The raspy noise grates at my nerves. Low, mechanic, industrious. I carefully climb down each step without bothering to turn on the lights. The moonlight drifts through the stained glass window to the stairwell, casting cut out shadows of cobalt blue and malachite green on the worn steps.

There's a soft glowing light coming from the living room. The door just slightly open, allowing the warm glare to permeate through the cold darkness.

I push the door open without calling out my friend. Feeling curious, but also reassured as absolute calm and tranquillity seems to reign in the first glimpse I get of the room.

Suddenly something sharp zooms past my eyes and I instinctively I step back, knocking me out of balance. I crash on the landing, no hope left of spying surreptitiously on my mad friend.

'John?'

Sherlock comes to the door, pulling it open, looking me on the ground with confusion.

'You could have come in', he decides on, shrugging and turning back to the room.

'Sherlock, it's the middle of the night!'

'Your presence never bothers me, John.'

Wait, that's not—

'No, I mean—' I sigh, knowing it's hopeless. 'What are you doing?'

He smirks as a small hint of victory but otherwise gestures at my chair. The strange flying blur still zooms about the room. I squint at what turns out to be a biplane model with a functioning motor and the control box is in Sherlock's hands.

I'm about to ask for information when the thing swerves sharply, dives its nose and heads towards me. I duck just in time.

'Sherlock, is that... Sherlock, what did you put inside that flying machine?' I demand an answer, thunderous.

'That's John II, my new rescue lab rat.'

'Do you call this a rescue? The poor creature inside it is probably praying to go back to an infectious diseases laboratory by now! Sherlock Holmes, land that toy airplane right now!'

The genius and mad scientist with the skewed ethics rolls his eyes but carefully bites his lip as he manoeuvres the commands to a perfect 10 points landing on the rug.

I rush towards the innocent captive animal inside. I'm relieved to see him sniffling around him in curiosity, with absolutely no ill effects from his adventure.

'I've trained him, John. Obviously. Little John is most able to board a flying device without suffering ill effects. In fact, I believe he positively loves flying.'

'How do you know that?'

'He twitches his whiskers.'

'Sherlock, he's a rat. He'll do that all the time regardless of the setting...' I take a deep breath and try to organise my thoughts and emotions. 'Why?' I ask, point blank, depleted by Sherlock's shenanigans.

'We've been through this before, John. You were unavailable, not to mention the size difference.'

'Sherlock...' I warn him with a growl.

'Take a seat, John', he invites me up the red armchair. 'Your bare feet must be cold by now, that always makes you cranky.'

I obey, stiffly, still waiting on those explanations.

'The last lab rat, you wanted to send her to the Moon', I lead him on. No, I haven't forgotten that.

'Baby steps.'

Sherlock fiddles again with the commands in his hands. I'm up in a flash, trying to stop him, but too late. The poor rat is again flying the fantastic machine.

'Sherlock, cut it out!'

The detective's cold grey eyes narrow and he brusquely raises the plane's nose, causing a tight loop on itself. I jump forward with my hands reaching out to catch the poor creature falling from the seat but in a burst of white fabric a bunched up ball of fabric bursts forth, immediately assuming the shape of a parachute, slowing John's fall.

There's a ruddy miniscule backpack tied to John's back. He hangs limply, sniffling the air around him as he glides down slowly to my outstretched hands. Frantic and frightened half to death but not harmed.

'Sherlock, you can't do this!'

'Clearly not. John does not partake on either your bravery or your need for adrenaline.'

Sherlock, ever so gently, returns the rat to a spacious cage on the coffee table. It has a hamster wheel and plenty of food and water. The little thing shrieks away to the corner, one red eye alert and studying us.

'John, he might partake in your PTSD. Remind me, how did you get over it?'

I glare at the detective, recover the rat and gently hold the little one to my jumper, settling him.

'Sherlock, you don't understand John at all', I declare, dignified, before I walk off.

.

Long day at the surgery. Seems like all mothers with runny nose toddlers have concerted their efforts to persuade me their children are possibly suffering from the most tragic illnesses and will not accept their bright sparks may be victims to the common cold.

I'm achy, tired and cold as I walk the short distance between the tube station and 221B.

What I certainly didn't expect was to arrive home to find a gigantic maze built on the living room floor, and expanded to the landing and stairs. The top of the boxed labyrinth is Plexiglas and see through. There's only but a short gap to the banister, allowing me safe passage to 221B. 'Sherlock?' I call. Nothing. 'Sherlock!'

'It's an escape room, John!' The detective materialises himself by my side, coming down the steps from the upper floor. The biplane is haphazardly parked on the third step. 'I'm trying to teach John, this John, to escape, by providing enough stimulus measures to encore him to do just that', Sherlock relays. 'Positive stimuli, John. By the way, we are out of cheese.'

'Yeah. How's that training working for you?' I ask, sarcastic.

'Slow and with great difficulty. John, you are a slow learner', he sentences before walking past me to Mrs Hudson or outside. I have to swerve out if the way in an unprecedented act of contortion. Belatedly I notice he's got his long coat on.

Was that John the rat or John the human he meant?

Have I been left babysitting a rat?

And what was Sherlock doing in my room?

.

A nice invigorating shower was all I needed to feel human again. Stretching my back and drinking my neck, I take a balled up bunch of dirty clothes for the laundry basket. Nothing could be more mundane, I suspect, and so when I actually drop the lid on musty towels and old shirts it's a surprise I spot the thing out.

'Sherlock! Your rat is in my dirty jumper!'

After a couple of seconds of absolute silence, suddenly there's a rush of noise and movement from a frantic flatmate heading over.

Absolutely blasé, I open the bathroom door and wait collectedly for the genius arrival.

Sherlock is genuinely concerned and relieved as he scoops up the tiny animal in his hands, bringing him to his cheek – and the furry creature affectionately sniffs his pale skin.

'There you were, you idiot!' there's no edge to his name calling of what has become his new pet. I mean, pet. 'I thought I'd lost you. Never leave, John. I'll do anything.'

'Sherlock, hmm', I need to warn him I'm in earshot, no matter the goldmine, 'you know he doesn't speak English.'

'No. He might learn to understand it though. Do not sell him short. John is cleverer than he seems.'

'Except he got lost inside the laundry basket', I state drily.

'Clearly he was ready to brave the waters next, having explored the skies and the land. I commend his bravery but do not condone wash cycles, obviously. John is prone to getting himself over his head in danger', he concludes with a responsibility laden sigh.

'John was actually enjoying a kip in my jumper. Maybe he likes jumpers.'

'Just drop it, John. Stop trying to make him like you, John. There's no need to get jealous, John.'

I sigh and roll my eyes.

I'm not the one that, feeling lonely or bored, has been caught transferring feelings to a pet rat.

'Sherlock, what's that in your pocket?' A strange twitch animates his dressing gown's pocket.

He gulps.

I stare.

He looks guilty.

I gulp.

There are other pet rats about.

All named John, I bet.

'I couldn't just leave them behind, could I? No one wanted them, they didn't have a home! I'm trying to keep them happy, but what do I know about rats? They are as big a mystery as you!

My face twitches in a smile.

Most genuine thing he's told me all day.

I can help. I like the little chaps too. And Sherlock is right; everyone deserves a loving home.

I guess it's my turn to get the cheese.

.