Sherlock glared at the sun - ruining a perfectly rainy London day, with its bright light and currently shining spectrum of -

"John!"

Sherlock paced - frantic, perhaps more frantic than John had ever seen him, even more than in the throes of withdrawal, or in the midst of a case. It was disturbing, to say the least.

"John. John Hamish Watson. When exactly did you decide to hide from me - to not disclose - That is, why did you think it was permissible to -"

"Out with it, Sherlock, before you wear a hole in the floor."

"Didn't you - did you not for one minute think it might concern me to know that you are - that you're a -"

"Say it."

Sherlock swung his body around to face John, staring at the man with a terrifyingly intense gaze.

"That you're a rainbow."

John sighed, rubbing his forehead and determinedly not looking at Sherlock. It wasn't as though it was a secret John had purposely kept from his flatmate-partner-boyfriend-plant. It just wasn't exactly relevant.

"It wasn't exactly relevant."

Sherlock looked positively flabbergasted, a term John thought he might never apply to the man. John took the moment to fully catalogue every feature, from the flaring of his nostrils to the rapid twitching of his right eyelid.

"JOHN!"

Of course, it couldn't last.

Sherlock resumed his pacing and, in the interest of his own sanity, John got up to stop him, approaching Sherlock as he would a frightened animal or a keyed-up Private. "Sherlock, Sherlock," he murmured, placing his hands on the detective's shoulders and sliding them up and down his arms in what he prayed was a calming manner. "I'm sorry. It's very personal for me, I didn't know how you would react. I only did it today because I wanted to cheer you up." John smiled hesitantly up at Sherlock.

"Do I look bloody well cheered up?" Sherlock snapped.

No such luck, then. John sighed. "No, you don't. I'm sorry Sherlock, I've told you. Come on, let's just sit down, yeah?" John expected resistance as he led Sherlock over to the couch, but it appeared that he was too shocked to even maintain his sneer.

"Are you alright, hm? Do you want some tea?"

"Do I want some tea?" Sherlock growled, and John could practically smell the oncoming Sulk. Defensive Manoeuvre Necessary. Act, Watson, act.

"Alright, alright," John said hurriedly, sitting as close to Sherlock as he dared, and settling his hand in his hair. Sherlock lost an almost undetectable amount of tension. Oh thank Christ. Just keep talking.

"Would it make you feel better if I told you how it happened?" Sherlock hummed deep in his throat. It seemed a little less malicious than his previous noises, so John figured it was safe to continue.

"Well, it may surprise you to learn this, but one in every hundred thousand British children is actually born a rainbow."

That this elicited no response from Sherlock was not a good sign. Well, best to soldier on.

"It's a recessive gene, you know. Strangely, a few carriers have the ability to change at will. It's hard to control during childhood, of course, but it can really be quite usefull - "

Sherlock shifted to face John once more. "Did the army know?"

"What?"

"Your fellow soldiers, your superiors, did they know?" Sherlock so upset was frightening, but Sherlock deprived of answers was even more so.

"Well of course. The army attempts to recruit all rainbow children." John failed to see why Sherlock was so enraged by this information. Unless - oh.

"They knew and you didn't." No response. "Sherlock - it's not like I did it for them, not like I would do for you. A rainbow in the middle of the desert would look a little off, now, wouldn't it?"

"Hmph." Sherlock was no longer facing him. Damage Control, Watson. John sighed.

"I told you, it's very personal. It's a power the ranks occasionally find useful, but it's not like I would go around flaunting it. I haven't done it since before I went off to Afghanistan."

Sherlock turned, curious. "Really?"

"Of course not. Even then, it was just to stretch my photons just in case this time was my last."

Sherlock huffed out a breath, seemingly returning from the brink of his Sulk, though by no means pacified. He blinked at John, almost humbly. Almost.

"So you did it this time... for me?"

John reached across the couch to grasp Sherlock's hand. "Yes, you daft bastard. Of course. I intended for it to pull you off the couch, but, well..." John chanced another smile.

"Yes." Sherlock sniffed. How someone could express so much disdain through such a simple sound would forever confuse John.

"Anyway, that's pretty much all there is."

"Is it?"

"Hmm?"

"Is that all that there is?"

"Well, I do also have a keen eye for spotting leprechauns." Sherlock stared. "That was a joke."

In the weeks following what John privately termed "The Big Reveal," Sherlock became erratic - well, more erratic - in his interactions with John - in conversation, at crime scenes, bloody hell, even during sleep! John had to practically head him off at every corner - of course he would try to experiment on John's rainbowhood, but it simply wouldn't do.

"Sherlock, I've told you a thousand times, I am not going to be one of your experiments. Not again."

"But John-"

"No, Sherlock!"

Sherlock huffed out a breath as his shoulders fell. John nearly felt guilty, but he had to stand his ground. "Listen, Sherlock. Why are you so fixated on this? I understand that it must be fascinating to you, but-"

"Fascinating?" Sherlock sneered. "No, I'd think not. It's practically pedestrian."

John sputtered. "Pedestrian!"

"Why, yes."

Sherlock threw himself unceremoniously upon the couch, vaguely waving his hand in the air. "Rainbowhood, John? As if I would be interested in such an incredibly dull phenomena. It's painfully obvious that your condition is of literally no relevance to my work - much like a cursory knowledge of the solar system - don't start." Sherlock shot a look at John before pulling his dressing gown around his waist and hunkering down into the cushions.

John bit back his words, and instead blew out a short breath. Well then why was Sherlock so obstinate about experimenting on him?

There came a muffled muttering from the couch.

"What was that, Sherlock?"

Sherlock turned over with an air of open hostility. "I said, I'm not experimenting on you, John. I promised you after Baskerville that I wouldn't. Honestly, do you have so little faith in me?"

"Sherlock, that's not what I - well, what the hell are you poking and prodding me for!"

Sherlock flushed, looking down at his knees, mumbling again. Sighing, John made his way over to the couch to join the man. Mood swings were becoming more and more frequent, and the least John could do was offer his company - or absence, depending. John settled himself close to Sherlock, a hand on his knee.

"I'm trying to know you."

It was almost enough to make John laugh, but it seemed painful for Sherlock to divulge this information, so John decided to take him seriously.

"Sherlock, you do know me!"

"Well then how did I not know you were a bloody rainbow!" Sherlock was a dangerous mix of anxious and royally pissed off. John sighed.

"So that's what this is about, then. The past month, the four patch problems, making Anderson cry?"

"Yes, yes. Well, not the last one, but - yes."

John touched Sherlock's neck, gently pulling the other man closer. "Sherlock, there's nothing more to know. You have all of me." John kissed the top of Sherlock's head, nose nudging at the dark curls, inhaling the scent of his own shampoo.

Sherlock was quiet for a moment. "Really?"

In lieu of a response, Sherlock got a sudden sense of disequilibrium, falling to his side on the sofa. Lying quite uncomfortably, heart beating painfully fast, Sherlock stared straight out the window, at the dreary London street, above which was John - his John - shining brightly for all to see.

But Sherlock knew, like he knew every molecule present in London soil, that it was all for him.