A/N: So this is a drabble based on a prompt I received from an anon on Tumblr. It got really deep, guys...if I get enough positive feedback or requests to, I might just make it into a full-fledged fic, and judging by this drabble I'd say it'd be long, smutty, deep, angsty, and well-rounded. Yeah, it's ot3 for Sherlock/Jim/John.


It has been going on for a while by that point, that much I knew. And however uncomfortable I was with it, there was nothing I could do to stop it. I had no real reason to, when I thought about it. It kept them both quiet (figuratively speaking). Or, at least it did at first. They were too preoccupied with one another to do anything about anything else. But then they fell into that grove. You know the one, where you get to the point in a relationship where you become comfortable, start to go off and do things apart from each other? Well, when that happened between them, things just got worse for the rest of organised civilisation.
Sherlock was happier, so it seemed, but, as per usual, it had opposite the desired effect. He was even more rude to people in his state of positivity than he had been when miserable or disinterested. The man had no filter to begin with, it just started to seem as though he was trying to out-dick himself. And Jim? Jim was a whole new level of psychotic. But that in itself wasn't the trouble. No, the trouble was was that Sherlock was no longer trying to stop him, it almost seemed as though he wasn't necessarily encouraging him, but rather ignoring that aspect of him. As though he'd forgotten Jim was the world's leading criminal.
I turned a blind eye to it, knew that the Yard could handle Jim at least well enough to keep him at bay, and knew that Sherlock could keep him from doing anything too terrible if he really needed to. I willed myself to let it be, told myself everything would be fine. I tried not to get too attached and involved. But the more time that passed, the harder it became to continue to just brush it all off. I was starting to become irrationally angry, depressed and, dare I say, incredibly jealous of Jim. I knew it was ludicrous to announce and be come aware of my feelings in light of such a situation, but I was growing proprietary. Sherlock was mine, dammit. Someone had to keep him in line, and that someone was certainly not James Moriarty.
And I resolved to make that known. Little did I know, as I marched up to Sherlock's room one night that I knew Jim was over, what I was about to be pulled in to. Shouting on my part turned to caressing on Sherlock's, turned to kissing on Jim's. Anger to agony to desire to lust, a myriad of emotions melting away into each other, sensations flooding me in an uncontrollable influx, a relationship moulding and transforming into something I would have never anticipated it to become.
I know you're asking for details, who wouldn't? It was an interesting night to say the least, and though I won't give you everything, I will partially quell your curiosity and give you a rough rundown of events.
It started off, as I said, with me storming up to meet the pair. I had, for whatever reason, assumed I wouldn't find them in any sort of compromising position. A stupid assumption, I know, and far be it from me why I made it. I had swung open the surprisingly unlocked door to find them lost in a tangle of limbs, hardly able to discern one being from the other. My face burned from my embarrassment, or at least I say embarrassment, as I turned to leave. But I heard a voice call my name, tell me to wait, not to leave. The voice didn't belong to Sherlock. I turned back to see Jim sitting up on the bed, having pushed Sherlock from him, staring deviously at me. At which point I lost it. I started shouting at him about how corrupting he was, what a bad influence he was, and what little good was sparking from this arrangement. I hadn't been my anticipation that Jim would make the suggestion he did.
"Well then, John, why don't you join us?" said he, to which I was utterly ripped of words. What does one say to a proposition like that? I hadn't the response, but luckily I didn't need one. Unfortunately for me, my willingness had already become apparent. Without my noticing, Sherlock had evidently wandered over to me, slowly beginning to rid me of my clothing. However, my eyes were fixed on Jim. I watched intently as he crossed the room to me, swiftly closing the gap between us and pressing his lips to mine. Without thinking, I spared no time in returning and pushing forward to deepen the kiss. Any resolve of decency I had had been ripped to shreds in that moment, I was sucked in. There was no going back. And it was bliss.
And when we woke the next morning, I thought there would be argument, regret, apologies, shouting, taking things back. But no such events occurred. There was no blaming anything on blinding lust, there was no claiming it was a rash decision. Each of us was satisfied, and even further, each of us was content. Collectively and wordlessly, the decision was made that the three of us had just begun what would be a long lasting poly-amorous relationship.
It was then that I realised that I had been incorrect all along; Sherlock and Jim were not opposites, but rather Jim was the photo negative of myself. I represented the valiant nobility, the law, the angel. Jim represented the unabashed evil, the merciless, the demon. Sherlock was the grey between the black and the white, the neutrality, the vigilante. He was neither good nor evil. I thought that Sherlock and Jim would balance each other out, but I was wrong. A spectrum cannot balance without all its components, harmony cannot be achieved without all the tones and pitches. A melody needs its dissonance, the pieces have to fit, the picture has to be whole. To attain the balance, we needed all three of us: the black, the white, and the grey. I needed Jim as much as I needed Sherlock, and the same went for the two of them. Only together could our picture be complete.
We keep one another in check, no two ways about it. Jim brings out the goodness in me, I the evil in him, and it needs to be that way for us both to bring out the brilliance in Sherlock. We all nurture one another. Our relationship is based not in any conventional sense of the word love, but rather in hatred, desire, and every definition of sheer need. We are desperate. We are one mechanised being, incomplete without all its parts. Alone we are insignificant, but together we are glorious.