Disclaimer: I do not own BBC Sherlock.

John didn't know.

Sherlock hadn't mentioned it in their brief meeting at St Bart's, nor had Mycroft brought it up when he had kidnapped John. The elder Holmes was probably relieved that his brother had found a doctor of all people to board with.

It had been nearly three months since they had moved in together. A tragically uneventful sunday afternoon. John sat in the chair facing the kitchen, a newspaper obstructing his view of whatever Sherlock was doing in there. Experimenting, he was always experimenting, either at 221b or at St Bart's, always going on about his blasted experiments that left body parts in the bread box and heads in the freezer.

"John! John!"

He always sounded so damn excited, though, whenever he made a 'discovery'. He finally had someone (who wasn't a skull) to share his findings with.

Inwardly groaning, John folded down the top part of his newspaper. He looked at Sherlock, who was rushing quickly from the macerated dining room, expectantly. The not-quite-scientist held a vial of some vaguely blue liquid and, eyes jumping, opened his mouth to speak.

But he hesitated then. His eyebrows furrowed and he stared at something distant, eyes unfocused and mouth agape.

Sherlock did this sometimes, yes, usually before stumbling across some big advancement in a case. Other times he'd snap out of it and look around, lost. "John?" he'd whisper.

But never did he do it in this manner, suddenly, mid-discovery.

The vial was the first to go.

It didn't quite shatter as it hit the carpeted area, just landed with a thunk and spilled its contents everywhere.

"Sh––" John began, but never got to finish.

Sherlock's eyes of blue or green rolled back into his head and his arms snapped towards his body and he dropped towards to ground after the beaker.

John was already on his feet by the time Sherlock started to convulse.

He knelt by his flatmate, heart beating rapidly as he quickly remembered seizure first aid. John unfastened the first few buttons of Sherlock's shirt and held his head steady as he shook, mind racing. Had he taken anything? No, no, John didn't think he'd be betrayed so quickly, and Sherlock had been experimenting all morning. And he was fine, god damn it. Not moody or bored or anything that would suggest that he'd take something.

John chewed the inside of his lip he watched the second hand on his watch and thought briefly about time, how it really was truly relative, how does one reliably measure it when two minutes feels like ages and oh god he's not breathing––

As Sherlock's convulsions gradually slowed, John rolled him onto his side, still cautiously cushioning his head. With his other hand, he flipped to his phone, hesitating. Should he call emergency? Or––would Mycroft know what to do?

"Sherlock?" The other man was still. John tossed his phone away.

Colour returned to his face and lips and finally, Sherlock opened his eyes. He didn't move at once, he just laid on the now damp carpet, staring under the cluttered tables, presumably thinking and deducing and coming to a conclusion (based off his position and touch of confusion and John's hands in his hair) about what had happened.

He worked his jaw, trying (unsuccessfully) not to wince. He wondered how long he had until the migraine set in and if John would try to talk to him and

"Sherlock?"

ah ah ah there it was, starting in the corner of his vast and nigh inexhaustible brain and spreading, infecting his nerves and consciousness with unmistakable pain.

"John," his voice was low so low, he didn't know if John could here him. "I'll explain everything in a few hours, please just––just leave me. I'm fine. Don't call Mycroft," he added quickly.

John wanted to rebuke, but before he could start to speak, Sherlock's eyes had slid closed.

John rose from the floor, not knowing what to do. It felt wrong to just leave him on the floor like that. Eyes searching, he too the union jack pillow from the sofa and eased it under Sherlock's head. The ex-army doctor swallowed and crept into the kitchen for a damp rag to clean up whatever had fallen and infused with the now-ruined carpet.

It was just to keep himself busy, though, and he knew it. After he sopped up what he could, John crept into the room at the end of the hall, drawing out his phone that he had recovered. He was surprised to see he had a message. It was from Mycroft, sure enough, and simply read, "Stay with him."

John had sat by Sherlock for the remainder of the afternoon.

His back was up against the sofa, newspaper abandoned on the floor. He would lightly weave his fingers around the man's inky black curls, subconsciously checking for any bumps on his head.

It was past seven o'clock when Sherlock began to stir.

His eyes fluttered open and he worked his jaw again. John drew his hand back and Sherlock moved pushed himself up.

"Easy, easy." With a firm arm, Sherlock was vertical, sitting like John against the sofa. A glass of water had been procured and Sherlock took it gratefully, sipping the lukewarm lifeline.

"Epileptic, then."

He drained the glass.

"You didn't mention it."

"You didn't ask."

"I didn't know I had to."

"I figured you had already looked up my medical records."

John was taken aback. "Why would I do that?"

Sherlock half shrugged. "You researched me." He swallowed and swirled a drop or two of water around the bottom of the glass. "Epilepsy. Yes. I was never too into wearing the bracelets, or such. There's a bit in my wallet, however. Thought you might have seen it when you took my card." He stopped from saying something about seeing and not observing.

John cleared his throat. "You take medication, then?"

Sherlock blinked. "Must we discuss this n––"

"Yes." John was unyielding.

"I have a prescription."

"But you don't take it."

Sherlock stared him in the eye. "I never said that."

"But––"

"I take it, yes, as often as I remember."

"Like you remember to eat." He was getting angry. "Am I going to have to have to remind you to take your medication now, too? Line up a pill and glass of water every morning with breakfast?"

Sherlock stared at John, scrutinizing him. John looked away.

"Why do you care so much?"

"Why d––Why do I care about your well-being? Is that what you're asking?"

"If you're sick of me, why don't you just leave? You have a job, you're well off, more or less. If you don't like it here, why stay?"

John gawked. The idea, the thought, had never occurred to him before, to just leave 221b, forever, He had stormed off plenty of times, sure, but never for good. He always kept coming back.

But why? It wasn't the company, really, John didn't know what Sherlock was blabbering on about half the time. It was a nice flat, true, but there were nice flats all over. And he didn't have to stay in London.

Why did he keep coming back?

John knew why, deep down.

If he left, he would revert back, his life would be a never ending spiral of nothing. He wouldn't go back to battle, surely not. His life would be boring, ordinary, and nothing would happen. On Baker Street, with Sherlock, things happened. He was whisked off to solve murders and have adventures, and despite everything, despite Sherlock's habits and personality and what have you, John could never go back.

Never.

"Someone has to remind you to eat" was all he came up with.

Sherlock looked away, poorly masked disappointment lining his features. "Hm."

After a minute, John, "Are you alright to walk? We could get, er, take away, if you like. Or I could go get it and you could stay."

Of course. John must have been staying with him all day. Humans. Sherlock figured he'd never understand them, as long as he lived.

"No, I think I'm alright now."

John helped him to his feet and watched as he took a few shaky steps around the living room, attentive if he faltered or swayed.

Then, they were walking down the street, the night brisk.

"John?"

"Yes?"

"Thank you."

"For what?"

"For staying."

A/N: If there are any glaring errors in my research or mechanics, please feel free to point them out. I try to have correct information in all my stories, but sometimes the thrill of fiction gets the better of me. I probably wont continue this, though I may explore more epileptic!Sherlock. What do you think?

Thank you for reading, feedback and reviews are much appreciated but not necessary.