'Sherlock, I hope you've cleaned out the fridge! I've just bought milk and I don't want any nasty surp- what is that?'

John Watson stopped short, his jacket half removed, one arm flapping languidly at his side. He watched the other man from the doorway with a kind of incredulous bemusement. Sherlock Holmes was sat in the leather armchair, managing, as usual, to appear at once both rigid and boneless, lounging comfortably but deep in thought, fingers steepled in front of his face. On his lap, inexplicably, was a small black kitten.

'It's a cat, John. Don't be deliberately obtuse; it's unbecoming.'

John squinted in frustration and then blinked rapidly. 'I know what it is. I just meant... what's it doing here?'

'Sleeping, obviously. I've been told they're quite fond of sleeping. And eating. And crying.' He picked briefly at a cuticle.

'That's babies, Sherlock,' John said patiently, folding his coat over his arm and cautiously approaching the chair.

'Babies, kittens, they're much the same, really. Their brains are fundamentally similar due to their undeveloped state.' He tapped his fingers thoughtfully, gazing at some unseen riddle on the far wall, eyes tracking rapidly.

'We're not keeping it, I hope you know.'

'Why not?' Sherlock asked, head snapping to the side to look at John. His eyes narrowed and he cocked his head to the side before turning back to face straight ahead, smiling slightly, fingers resuming their incessant tapping.

'Well, Mrs. Hudson is allergic, for starters.'

'No she isn't,' Sherlock shot back. 'She used to keep a large number of cats when she moved to this building after her husband's... death.'

'Really? That's odd; I've never heard her mention that,' John said suspiciously.

'She didn't have to,' Sherlock answered, not bothering to look at John as he lectured. 'See the baseboard over there?' He pointed into the corner of the room. 'Small scratches on the wood, but the finish is new. Someone painted over the claw marks to hide them from future tenants. And that small section of the carpet behind the door has been steam cleaned several times. Animals mark their territory. It's a fact of nature.'

'Maybe whoever owned these flats before Mrs. Hudson had the cats. How do you know it was her?' John retorted.

'Think about it. If the cats had belonged to someone else, she would have replaced the baseboards and the carpet entirely. She loved those cats and the thought of completely erasing the memories of their existence was too painful for her.'

'Oh, come on! That's a bit of a stretch.' John threw up his hands in annoyance.

'Is it, John?' Sherlock asked, looking at the other man pointedly. 'Think of any of the pets you've owned.'

John rubbed his face in frustration and gritted his teeth. 'I've never owned a pet. And frankly, I'm surprised that you have. I assumed that they'd be too... high maintenance for your lifestyle.'

'You assumed wrong,' Sherlock said quietly, steepled fingers now tapping furiously against his pursed lips.

John sighed. 'Sherlock, I'm sure you and Mycroft have some lovely childhood memories about Goldie the lovable cocker spaniel, but we are not. keeping. that. cat.'

'Give me a reason, John. Just tell me why you don't want to keep this cat and I'll agree.'

John's hands went to his head, gripping his short hair angrily. 'Pets require care and attention, Sherlock! You can barely remember to feed yourself! I'll end up having to do all the work!'

Sherlock raised an eyebrow, ever so slightly. 'That's not why you don't want to keep the cat.'

'Oh? Is it not?' John was practically yelling now. 'Why doesn't the Great Sherlock Holmes tell me exactly why I don't want to be saddled with another responsibility?'

'You're scared,' Sherlock said simply, quietly. 'That's why you're behaving so irrationally now. I saw it in your eyes the minute you walked in the room. You've always been afraid of cats. Ever since your sister's cat died when you were young. You don't understand animals, can't talk to them, can't help them. They can't tell you what hurts so you can't fix them when they're broken.'

John stared, open-mouthed. 'How did you know all that? No, don't tell me.' He held up a finger when the other man opened his mouth to explain. 'I don't even want to know.'

'I was right, though, wasn't I?' Sherlock asked, face calm but eyes shining with excitement.

John took a deep breath and then looked away, blowing out the air in a long, controlled stream. 'Yes,' he admitted finally. 'You were right.'

'I knew it!' Sherlock yelled, jumping to his feet. 'I mean, I didn't know so much as deduce, but...' He stopped short and John quickly glanced back at him, puzzled as to why he had stopped talking.

When John saw what had happened, his face lit up. In his excitement, Sherlock had apparently forgotten the kitten resting peacefully on his lap. The result was quite comical. A confused and pained looking Sherlock was standing stiffly in front of his chair, an angry black kitten clinging tightly to the legs of his now vertical trousers.

'Okay, okay,' John said once he had gotten over his fit of giggling. 'Anything that can cause you to make that face is welcome in the flat. But you have to take care of it. And it is not sleeping in my room!'

Sherlock, having finally extracted his legs from the kitten's grasp, was back in his seat in the armchair, kitten resettled on his lap, the former situation completely forgiven. He smiled smugly at the other man.

'One of these days, Sherlock, you won't get your way. And what'll you do then?' John headed up the stairs to his bedroom, shaking his head.

Sherlock remained in the chair, a half-smile across his face. As he heard John making his way upstairs his head slowly tilted back until he was looking at the ceiling, waiting. He stroked the kitten's head slowly, one finger at a time, until he heard a sound which could only be caused by a head striking repeatedly against a plaster wall.

'SHERLOCK!' He grinned as he heard the wail from upstairs. 'What is this pet bed doing on the floor of my room?'