Chapter Text
"It's like this." John whistled through his teeth as he looked for a way to explain it. "Mum's from Innsmouth."
Sherlock frowned at the unfamiliar name. He still wasn't sure what this was about. "Innsmouth? I've never heard of it."
"Of course you haven't. Little town by the sea in New England. She was born there. Though maybe I should start with my grandmother."
"Are we sharing family histories now? I ought to have texted Mycroft."
"Sherlock. Listen. Please. My grandmother wasn't from Innsmouth, not originally, but her family moved there when she was a kid. Um. Actually it might be a better idea to start with my grandfather--"
"Also from Innsmouth?"
"No. Definitely not. Though he visited the place. Probably still does."
"He's still alive?"
"You know, I can't even wrap my head around the thought of him being dead. Not that I've met him. Not that I want to meet him, when it comes to that."
Sherlock let his flatmate have a quiet moment to contemplate his familial difficulties.
"Anyway," John went on eventually, "my grandmother came to Innsmouth, and my grandfather came there every so often, and my Mum and my uncles happened before my grandmother got married to an Englishman."
"Ah."
"He was a very understanding bloke, and my grandmother liked him, but he didn't want her to stay in Innsmouth, and she was pretty glad to get out of there, to be honest."
"I take it she didn't like your grandfather very much?"
"Look, it wasn't - it wasn't your conventional setup, all right? Maybe she liked it at first, maybe she didn't have a choice, and, God, I do not want to think about my grandparents' sex life, if you don't mind."
Sherlock gave him a look to say that he could imagine quite a few non-conventional setups, no need to be queasy around him.
"Anyway, Mum was all right, her first brother was stillborn, Uncle Phil wandered into the sea during a summer holiday at Cornwall and never came back out, and Uncle Henry eventually had to be shut up in a mental institution. He, er, escaped, and we never heard from him again. I've got other uncles who're normal, but they're Mum's half-brothers.
"And then Mum married Dad, and they had Harry, and she was fine. And then they had me. Er." John scratched unconsciously at something at the small of his back. "I'm a bit of a throwback to my granddad."
"I don't see any problem there."
"Well, I've kept it under wraps, haven't I? I've gotten good at keeping it secret. Mum knows, of course, Dad knows though he was floored by it, and sometimes I wonder if knowing drove Harry to drink. I used to enjoy giving her a scare before I knew any better. She still can't stand the sight of an octopus." John's face took on a thoughtful look. "And some of my old girlfriends know. And old boyfriends."
Sherlock made an impatient noise. "And the point of all this is?"
"Granddad…he wasn't a person."
"Oh, for God's sake!"
"Seriously, Sherlock, he wasn't human. Sometimes I wonder if he's even a 'he', they don't have nice and orderly sexes like we do. Like you do, I mean." John took a deep breath. "My grandfather was one of the Deep Ones."
"The Deep Ones?"
"The Deep Ones, the Old Ones, the Great Old Ones, if you're so inclined. They're not from" - John waved a hand around vaguely, as if trying to indicate the entire world, no, the entire universe - "here. I don't rightly understand it all myself, and I don't actually want to understand it, but given the state of things, I've had to try and figure it out. Just a little. Just enough.
"I'm not even sure which one Granddad was. All I know for certain is that it wasn't one of the major ones, Dagon and so on. I think he was at least some part human himself, which is why it worked out so well for my Mum and Harry. They're just carriers, you see. They get off okay. But it's a little different for the men in the family." His mouth twisted in a grimace. "Thanks to Dad being completely normal, I don't have it as bad as, say, Uncle Henry. But I do have a set of tentacles."
It was a mark of Sherlock's great self-control that all he did at this was revelation was blink, twice. "What?"
"You heard me. I've got tentacles, a set of them. I can't tell you exactly how many, that changes. The Deep Ones, well, they basically tell the laws of physiology and physics and logic in this universe to go and fuck it, and the bit I inherited from them does that too." John's face darkened. "I've tried to get rid of them - why do you think I became a doctor? - but nothing's worked."
The consulting detective looked his flatmate up and down with that weighing, measuring, calculating look of his. "You're pulling my leg," he said finally.
"What do you think I am, nine years old with an overactive imagination?" John demanded indignantly. Sherlock was about to point out exactly why it couldn't possibly be true when the doctor pulled up the hem of his jumper and a long, twisty something snaked out from under it, looped around Sherlock's ankle and gave it a light tug. "Now I'm pulling your leg."
For once Sherlock was utterly speechless. He watched openmouthed as John removed the thing - yes, it was a tentacle, wasn't it? - from around his leg and slid it docilely back beneath his clothes. "Why are you telling me this?" he asked quietly, after a rather uncomfortably long silence.
"Because you're my friend. And I live with you." John had rearranged his jumper and was looking at him with that defiant jut of his chin that he got whenever he was about to face anything particularly challenging. "AndIfancyyouallrightitdidn'tseemfairtosaysoifyoudidn'tknow."
"Ah." It was the wrong thing to say to something like that, and Sherlock knew it the moment John's face took on a rigid, set expression. This wasn't an area that he was comfortable with, that he didn't usually care about, actually, only in this instance he did care very much, but he didn't know how to go about it. Saying I fancy you too actually would be honest but anticlimactic and Sherlock could quite bring himself to say the words, not after months of not saying them, and I don't mind your extra appendages wouldn't be quite true - the fact was too new, he didn't know how it computed yet. An observation, though, that would be safe. "That's why your old girlfriends knew."
"And boyfriends," John reminded him, matter-of-factly. He was less wired now that he'd got it all out. "I think I might have gotten that from Granddad too. Er. Sexuality, I mean. Lack of boundaries regarding it, more like. They're really not anything like humans at all, Granddad's people."
"So I gather."
John licked his lips. "There's no hiding it when the clothes come off, you see. So I either have to come clean or come up with a very clever explanation as to why the sex has to happen with me fully dressed except for the important bits." He smiled wryly. "They do make for a pretty interesting sex life though, once the secret's out of the way. Not," he added, "that it matters." Since you're not interested went unsaid. "But at least you won't be running for an exorcist or the like if you walk in on me in the bath." And he gave his flatmate what was meant to be a hearty grin before walking to the stairs that led to his bedroom.
"Wait," said Sherlock. He pressed his lips together in a hard line before going on. "It does matter."
"Sorry?" The doctor stopped in his tracks, turned around to face his flatmate. He sounded like he hardly dared to believe what he was hearing.
"It. Does. Matter." Sherlock went over to John, put a hand on his arm in a gesture that became surprisingly intimate. "I believe you said 'interesting'?"
And that was as close to a confession of undying love (with great and liberal amounts of prospective sex) as he was about to get.