A/N: I wrote this in response to a fic prompt I got on tumblr, where I had to write myself moving into 221C Baker Street. As such, the details about myself are true [or what I deem to be true about myself.] I just thought I'd share it.

Also, this is set pre- and post-Reichenbach.

Lamentando: music terminology, meaning "lamenting, mournfully."

The flat was colder than I'd been expecting, but I suppose it explained why it had been going cheap. It was also a basement flat. 221C Baker Street, the flat underneath the famous duo who fought crime.

OK, so maybe I was exaggerating a little. I'd read on the internet one of the blogs made by John Watson about his somewhat eccentric flatmate, and I'd also read in the papers about his solving of an apparently unsolvable case. I was interested, but I certainly wasn't going to turn fangirl on them. I had my studies to concentrate on, anyway.

The first time I met Sherlock Holmes was to be an experience I would never forget. I use the term 'met' loosely. I heard him first. Or rather, the series of gunshots he put into the wall. I'd practically leapt off my bed - I'd been doing some reading for my course and the flat had been relatively silent. I'd never heard a gunshot before, so, curious, I exited the flat and made my way upstairs. Up there, I found Mrs Hudson, my landlady, and two men, who could only be Sherlock Holmes and John Watson.

"Sorry," I said, feeling like an outsider all of a sudden. "I just wondered if everything was OK."

"Now look what you've done, Sherlock," Mrs Hudson scolded. "You've interrupted Caitlin and her studies."

I cringed, not liking the attention. "It's fine, honestly. I was getting bored anyway," I said quickly, my face going more and more red as I did so.

"We should be apologising," the shorter blonde man said - presumably Watson. "Sherlock's just having an off day."

"I'm bored," a deep baritone complained, a gun suddenly soaring through the air and landing on the carpet with a soft thump. I jumped, half expecting it to go off. Watson smiled at me. "It's OK," he said. "He used up all the bullets on the wall."

I peered around the doorway, noticing a bright yellow, spray painted smiley face, now complete with bullet holes. I then noticed the tall man sprawled on the sofa, in pyjamas and a blue silk dressing gown. His eyes flicked toward me, and then up at the ceiling.

"Who's she?" he asked, closing his eyes.

"I uh... I live in the downstairs flat," I answered. "I heard the noises and wondered what was going on."

I made to leave, but his words stopped me. "You should start playing your instrument again. It might make you feel less alone than you do at the moment. I find it helps when you can't express your deepest feelings, either because you don't know how or you feel you have to appear strong."

I sputtered, not knowing what on earth to say. So this was one of Sherlock Holmes' famous deductions. So I went with a reply that I would later realise confirmed his deductions: I had to appear strong.

"Hey, if you've got the two grand to pay for an oboe, then I'll play to your heart's content."

I left after that, heart hammering in my chest, ignoring the sympathetic glance from Watson or the kindly (yet still sympathetic) look from Mrs Hudson.

I didn't see the pair for a while after that, but I read about them online and in the papers. One day I was arriving home late from a lecture that had overrun, and they were on the doorstep, talking about something which I assumed to be their latest case. They were stood in front of the steps to the flat, but Holmes seemed so... animated, so alive that I didn't want to interrupt him mid-flow. He was completely different to the laconic, tired man I'd seen in their flat before.

So I held back, hovering nearby, clutching my bag like it was a life support system. Watson was the first to notice me, and he nudged his flatmate. "Sherlock, I think we're in her way."

"It's fine," I said quietly, not really wanting their attention: Holmes' analysis of me before had gotten to me. He had been right, things that affected me to my core stayed with me for a long time, and I didn't really have a way to express my feelings.

I paused when Watson asked me how my course was going. I stammered a few lines, outlining the basics of it. I didn't know if they were particularly interested, but Watson smiled and nodded while Holmes just stood with a neutral expression on his face.

"I, um, I heard you play the other night," I stammered, face going red. "The violin," I said, when Watson frowned. "You're very good. I haven't heard music like that in ages."

"Thank you," Holmes said quietly. "You still haven't sorted out yours though."

I wondered whether he'd remembered or deduced it from me again. I shrugged in answer, however. "Like I said, oboes are expensive. It's bad enough living here, I don't have the money to buy an oboe. Not a decent one at least."

That was one of my vices: if I were to ever play an oboe again, it would have to be like the model I'd previously had to give back to the music services at my council when I left college.

"How did you know that, by the way?" I asked. "That I played, I mean." I looked at the floor as the laser-sharp gaze of Holmes rested on me.

"Your hands," he said. "Playing an instrument myself, it's easy enough to recognise the signs of an instrument player. I would have guessed woodwind anyway, as you have a peculiar bending in your little fingers, like many do after years of having to stretch for the feather keys at the bottom of your chosen instrument. I knew that you hadn't played in a while by the lack of music coming from your flat. You'd been there for quite a while and yet no music came from your flat. Ergo, you weren't playing anymore."

I understood part of John Watson's blog posts now. When he explained, it seemed so simple. I'd noticed the bending in my fingers before, I'd often laughed about it with my friends, and freaked them out in due turn.

I nodded, not really knowing what to say, and then turned to go to my flat. Then I stopped and turned. "Good luck," I said. "With your case. I assume you have one, you don't really leave your flat otherwise."

That got a wry smile from Watson. "Thanks," he said, and I smiled in return, before entering my flat.

I was away when Holmes leapt off the roof of the hospital. When I returned to London I saw the change that hovered over 221B and the surrounding neighbourhood. I refused to believe Holmes was a fraud. I'd met the man, there was something about him, sure, but it definitely wasn't a faked persona. Whatever that Moriarty guy had done, though, it had prompted the man to commit suicide. I wondered what it must be like for Watson, in that flat. Empty, alone, cold.

So I made an executive decision. It took a few months saving of my student loan, with me practically living on the cheapest food I could find, but I saved enough.

I bought an oboe. Second hand, not as nice as the one I'd had before, but it was in good condition and still produced a clear sound. I'd always thought the oboe to be somewhat melancholy, and when I got it out of its case in my flat I realised how saddening the instrument could be. When I tuned it seemed to echo, but that could have been just the sparseness of my flat.

I tried to remember what song it was Holmes had been playing that night I'd heard him, so long ago. I hadn't recognised it, so it must have been a composition of his. So I played tunes I knew – some happy, some sad, some fast and some slow. I played all I could remember.

The oboe is a pretty loud instrument when it wants to be. One of my old orchestra conductors had said that the hardest part is getting an oboe to play quietly; just on the edge of the reed, and it was true. The oboe wasn't designed for quiet notes, but I managed OK.

I was playing Fauré's Pavane, which someone had once told me was a lament for a dead princess – I didn't know if it were true or not. Perhaps not the most appropriate considering the circumstances with which I was playing, but it was one of my favourite pieces. I had just finished it when there was a timid knock at my door.

I didn't get visitors as a rule, so it came as a shock to me. I opened my door cautiously, to find John Watson stood there. He bore all the hallmarks of a sleepless night – I'd had a load of them writing essays and the like, but his lack of sleep had obviously been caused by something different.

We stood there in silence for a moment, before he spoke.

"I heard you play," he said in a quiet voice, one that hadn't spoken in a while. "It was beautiful."

I thanked him, before noticing the music he had clutched in his hand. "I found this in Sherlock's stuff," he said. "I wondered if... if you'd be able to..."

He trailed off, the emotion clear in his face and voice. So I took the music, looking it over. As well as a detective, Sherlock Holmes had been a fairly decent composer. None of the songs had titles, except for one, which was simply titled with a single letter: "I".

"Come in," I told him, directing him to a chair while I placed the music on my stand, and then made some tea for my guest. I was nervous, it had been ages since I'd played in front of an audience that I didn't know, and this music was obviously quite personal to Watson.

I placed the one marked "I" on my stand first, and played it. There were no dynamics on the music, but I felt it needed to be played quietly. So I did so, running through the song as the man had written it. His notation was clear, precise. It looked as though he'd not changed a single note once he'd written it on the paper.

While I was playing, I looked up and saw Watson with his eyes closed. He was crying. I then noticed that I was crying too, as I finally recognised the piece I was playing. It had been the one I'd heard Holmes play so long ago.

I felt like I could never do it justice, but I did my best. When I finished it, and the other pieces he'd brought I offered a smile to the man.

"Thank you," I told him. "For... For this," I said, gesturing to the music, before handing it back to him.

He stopped me. "Keep it," he said. "You'll make better use of it than me."

I was silent for a moment, knowing it must be pretty important to Watson. "Are you sure?" I finally asked.

He nodded, and with a quiet "Thank you," he left.

The next night I found a note under my door.

You play beautifully. I'm glad my music didn't go to waste. SH.