This won't make a whole lot of sense without reading Visitor, things in trees, and departure. Essentially, this is a sci-fi AU in which John has known about and worked with aliens for most of his life. This story in particular recounts the events that got him involved with aliens in the first place.
Sherlock tosses his broad-brimmed straw hat aside and flops down on the beach towel next to John, scooting close. He drapes an arm over John's chest and rests his head on his shoulder, just over his scar. "High tide."
"I wasn't aware high tide meant cuddling," John teases. Sherlock is one of those people who shakes and shakes with cold when they run fevers- he'd spent last month's two-week bout with influenza either wrapped around John or sulking in the steam bath. He's apparently developed a taste for the cuddling, however, and has taken every opportunity since to drape himself over, next to, or around John.
"You're warm," Sherlock replies, even though he and John are both perfectly aware that it's nearly thirty-two degrees even in the shade of the cabana.
John gives a mental shrug and slides his arm over Sherlock's shoulders and the slick, smooth, brilliantly silvery-white material of his bodysuit. It's blazing hot to the touch—Epsilon Virginis is considerably more blue than Earth's Sun, so everything gets that much hotter if left unattended. For humans like John and Sherlock, full-coverage UV-blocking suits, hats, and the cabana are a necessity for days on the beach or out in the city. Jedara's ozone layer is impressive, but human skin just isn't evolved for such a balance of wavelengths. "Find anything interesting?"
"A ten-centimetre-long creature that resembled nothing so much as a miniaturised plesiosaur," Sherlock says. "It massed approximately five grams and its hide had a striking pattern of yellow rings on cobalt. I used the net—such colours tend to indicate toxicity on this world."
"You'll have to show me any images you took," John remarks. Tiny venomous space dinosaurs and Sherlock Holmes exploring his inner cuddle addict—who knew?
Sherlock traces delicate fingers over the ridge of John's clavicle. A period of silence passes, filled only by the roar of the surf, the wind in the trees further up the shore, and the squeaks and squawks of shore-tykke. At length, Sherlock speaks. "Tell me about being borrowed by Fountainheads again."
John smiles. Sherlock may claim to hate repetition, but he never seems to tire of John's retellings of his adventures in space before Afghanistan and their time in London. "Well, it was during the summer I spent with my Grandda and Harry up in Scotland..."
Going to Grandda's house in the country is brilliant.
John has never seen so many trees before in his life, nor has he ever seen such big fields, except for maybe that time they went to London and there was a park with big fields in the middle of the city. Those fields had city all around them, but these just have more trees and more fields.
Harry doesn't like it. She stays inside with Grandda or climbs the tree in the front yard, but never goes out past the fences. John likes that Harry doesn't follow him when he goes on adventures. She cries a lot.
John is going on a Grand Adventure today. He has his backpack and his Mr Bump plasters and a jar of water (he is too big for baby bottles (they're for babies), but sippy cups would spill and ruin his plasters, so he cleaned out a jar to carry water in) and an apple and a carrot, and he has his Big Stick he'd found the other day. He couldn't find any rope or grappling hooks or a sleeping bag, but that's okay, because dinner tonight is bangers and mash and those are his favourite, so he reckons it's best to get home in time for that.
The woods seem like a good place to start a Grand Adventure, so John goes there first, whacking bushes and thumping other sticks as he goes. He pretends that they're the trolls that had tried to eat Bilbo and the Dwarves in Grandda's story book. Really, the best way to beat a troll if you didn't have a Wizard around would be to hit him on the head, but Hobbits and Dwarves were small and probably wouldn't think of that. John is small, too, but he is very clever.
He's thwacked three fives of trolls when something strange comes out from behind a big bush.
It's a bubble, a bluish bubble full of clouds and some sort of... upside-down jellyfish thing.
"Hello?" John says. He drops his stick because he doesn't want to accidentally pop the bubble and make the jellyfish angry. He got stung by one in the ocean at Cornwall and that had hurt. He doesn't want to be stung again.
The upside-down jellyfish makes a basket with some of its feelers. "Hello, human child. Our vehicle requires repairs," it says in a strange, squawky voice.
John isn't sure how to respond. His Mum has talked to him about Strangers and how he's never supposed to help them with anything or pet their doggies, but do upside-down talking jellyfish count as Strangers?
Probably not. Strangers are people, not jellyfish in bubbles. John offers to help.
John sits quietly on a stool while the first jellyfish (Garnet Spark, because it has lights in it that look like Mum's birthstone when he holds it up to the light) wiggles at another jellyfish (Two Blinks, because its lights blink twice in a pattern). After a lot of wiggling and waggling, they bring over a funny hat and put it on his head. It has lights and shiny bits.
Suddenly, it's as if someone has opened up his thoughts like a room full of bookshelves and has started piling things onto the shelves. Maps, languages, maths, histories, log books, detailed anatomies, names of species, government systems, laws—more and more information pours in, settling neatly into the shelves.
This continues for some time. When it stops, the jellyfishes—Fountainheads, John knows now—finish their upload, they close the connection to John's mind and set about performing a hard reboot of their ship's mainframe. Clever of them to use a human child's mind as a hard drive; the sheer flexibility of a child's as-yet-unpared neural connections is exactly what they need in order to protect their data during repairs. John's glad that he happened to pass nearby. They would have had to go into town to find a child otherwise, and that would have just been a disaster.
As minutes turn to half-hours, John only watches the repairs in passing, too busy poring over the mental images of the inner workings of different species of extraterrestrials. The silicon life in particular is fascinating, though he doubts he ever wants to visit one of their homeworlds. The pressures and temperatures necessary to render silicon-based molecules malleable and reactive enough for the processes involved in complex life are a bit terrifying.
Venus would do well, in that respect, but the general galactic consensus is that humanity would make dreadful neighbours, so no one's bothered to colonise.
Too enthralled to bear to part with the information once repairs are done, John lifts and copies the mental 'books' with the anatomies and medical things, tucking them away in a different mind-room with its own shelves. He brings over an armful of languages, too, just to make sure he'll be able to remember the meanings of the things in the medical stuff. He decides that the relevant chemistry and much of the biology would be good, too, and then adds in maths because chemistry and biology are toothless without maths, but that's about as far as he gets because, upon returning to the borrowed mind-room, he discovers that the shelves are empty again.
John's attention returns to the outside world to find Garnet Spark and Two Blinks standing in front of him. "You were of tremendous assistance," Garnet Spark says as it removes the funny hat (John knew there was a name for it, but he hadn't gotten around to copying it down before the Fountainheads had finished fixing their ship). "It is probably best if you hurry home. Your progenitors may feel concern if you are absent for too long."
John decides to keep his copy-and-pasted files secret; some instinct tells him that he's not exactly supposed to know about the things he's copied down. He nods, hops down the ramp leading up to the Fountainheads' spaceship, and watches as it blinks out of existence.
He goes right home, finds a blank notebook and starts writing.
"My primary school teachers never did know what to do with the drawings I left all over my homework and my tests," John remarks.
"Idiots," Sherlock says as a matter of course.
John doesn't bother to correct him—the frequent calls home to his Mum about 'scary images' and 'possible implications' had been a source of endless irritation, both to him and to Mum.
"It was worth it," he says instead, carding his fingers through Sherlock's curly hair. "It got us here."
Sherlock nods and closes his eyes, dozing to while away the hours until the tide drops again.
Fountainheads are the creations of the inimitable Alastair Reynolds. Go read Pushing Ice. It's one of the best science-fiction novels I've ever read, right up there with Dune.