This has been bouncing around in my head since Serenity came out. The pairing of Senna/River is just so tantalizing. A little crazy, a little oddball and a lot smart. A lot creepy.

River remembers dreaming for as long as she's been alive. She remembers dreaming about things that happened when she was awake. She doesn't remember when the dreams shifted from after the happenings to before.

It probably means something that she never once dreamed of Senna.

They have to cyro River to bring her into the Academy. The minute she enters their airspace she knows something is wrong, and she can't stop screaming.

She dreams the whole time. She dreams about gunshots, people lying down but not sleeping; moon, water, music, steel. She dreams of Simon and home and dancing, but in the end it's all tainted red, and when she wakes up she's still screaming.

It doesn't matter. She can scream all she wants here. No one cares.

Her roommate is different. Different in all things. Quiet in all things. Even when they brought her here, even when the Blue Hands come for her. She never screams.

She says her name is Senna Wales.

They – they, meaning everyone River isn't, everyone whose thoughts she can stick her sharp little hands into and sift through – say they found her in a desert on one of the fringe planets. They don't know how she got there or how she survived. They don't know how old she is. Impossible to say. Her physiology is different. Still human, of course, but there's something in her that shouldn't be there, and some things that should but aren't. Anomalous in both body and mind, when the rest of the students here are only strange of brain.

Strange of brain, River thinks ruefully, pulling at her hair. Strange of a lot of things.

But River likes Senna. Likes her as much as she has ever liked anyone. On the darkest of nights, the nights after the Blue Hands have come for her, the nights when her head is spun raw and scraped thin and River couldn't dream if she wanted to, Senna will tell her stories. Of Earth-that-was, mostly. Stories about a girl and a group of boys who have implausible adventures, like the old Greek epics they have in libraries on Osiris. Egyptians and Romans, people with names like Loki and Merlin, wolves the size of transport holds, beings that traveled around on wings.

They're better than the stories Simon used to tell her. Simon tried, always, but he never was very good at stories. He didn't have the imagination. Simon was never very good at lying either. Not like Senna is.

River likes Senna – admires her – because Senna is the only one who lies to the Blue Hands and gets away with it. Senna says she doesn't remember anything before they brought her here, and they believe her. They want to believe her. River can feel it. They're afraid of what the truth would be. Words float through their heads when they think of Senna - old words, words they picked up in the paperbound books they read to write their theses in UniCad, in the tales their mothers and grandmothers told them when Earth-that-was could still be a true memory. Vampire. Witch. Goddess. They think about power, mostly, from a little slip of a girl they don't think should have it. They'd rather she lied to them.

River doesn't know what Senna is any more than the Blue Hands do, but she would like to know almost as much.

The thing that River can't get used to is the quiet. The mental quiet, not the physical. That River can't read Senna's thoughts is more disturbing than one would think. What do they say?

It's quiet. Too quiet. in a Western drawl, and the smell of leather and dust all around her.

Yes. Like that. River is so used to the thoughts and to the constant buzz they bring that the quiet is unnerving. She can't remember a time when she couldn't read thoughts. She can't remember anyone whose thoughts she couldn't read.

She remembers Simon's mind with fondness. The well-ordered neural pathways, emotions contained but always within reach, memories and facts floating freely, in constant flux. Ordered chaos, brilliant and bright and just like her brother.

She remembers her parents' as something more diminished. Her father was a work of art, in its own way. Orderly and clean and sterile, everything running on lists and schedules, precise as clockwork. He reminds her more of the Blue Hands than she would like – cold efficiency combined with large expectations, and a harsh and clinical kind of disappointment when those expectations were not met. Her mother was more chaotic. Always full, always changing, but never to anything substantial. Memories rising and falling, emotions swirling, neuroses surfacing. Like smoke and damp and River was always just as eager to get away from it.

It's odd, the silence, but at the same time it can almost be a relief. Being with Senna, with her mind so smooth and dark. It reminds River of water, of the surface of the lake Simon took her swimming in once, but told her not to drink from because water that dark was brackish. Polluted. But that doesn't make sense, does it? The association? Because Senna isn't water. Not any more water than the human body would typically be composed of, anyway. At least River would assume so.

It's a faulty analogy, River thinks. All analogies are. One thing is never another, and there's no use pretending it is. There's a saying from Earth-that-was – something about apples and oranges. It's true. You can't even compare apples and apples. Red apples, green apples, golden apples, love apples, sweet apples, poison apples, tart apples, apples picked yesterday versus the week before, apples that are baked into pies and apples that fall by the roadside, riddled with worms. Even an apple has its own destiny.

River and Senna are roommates. They are not friends, at least not in the way River had come to understand the term. They don't share secrets, or giggle, or talk about fashion and which boys are cute. They barely talk at all. They exist in the same space tolerably.

Once – only once – River thought about kissing Senna. She's not sure exactly why. River doesn't know if she wants Senna or not. She barely understands what I want /i is. She was never very interested in sexual interaction before, just on the cusp of such misadventures when she came to the Academy.

Such things are not encouraged here. Even the chance for such things is not permitted. There are no recreational times, no minglings between the student-experiments, and those who are ambi or sly get their own rooms.

Not that it might not eventually happen, whether she wills it or not. She's picked up thoughts from her handlers, from the doctors who watch her too carefully as she changes. A low-grade lust. Because she is pretty, because she is subservient, because she is their patient. Any number of things.

She's surprised the Blue Hands haven't tried to breed her yet. Sixteen, and her body ready for it, if not ripe. It will only be a matter of time before they consider it. Perhaps they all ready have and are merely hammering out the specifics. It wouldn't surprise her. She doesn't have to be psychic for that. And there are worse things, she supposes, than to grow a child inside of her. Something to have. A little secret they could never quite take away from her. Something they couldn't possibly feel.

Then again, perhaps the Blue Hands cannot afford to breed them. She would lose some of her purpose, if she were pregnant. She would be no good as a large weapon. Clunky, without the power to back it up. She is their blade – slim and fast, discreet and well-cloaked. A creature of unusual grace. There is nothing discreet, nothing graceful about a breeding woman, and procreation is not the kind of power they're looking for.

Not that River has to worry about any of that with Senna.

River comes to decide that Senna isn't even all that pretty. Not in the fashion favored by the elite of the Core planets, anyway. Too light. Milky skin, pale blonde hair that is nearly white. The Elite are Chinese and Japanese, French and Russian. And of course there are always a few who manage to break ranks, but only a select few. There are not many blondes in the elite. Almost none that don't come out of color treatments and chemical enhancements, anyway, and they just don't do the color justice. Not in River's opinion.

Not that she spends that much time thinking about Senna's hair.

Sometimes the Blue Hands bring her into the White Room. It's by far Senna's favorite – if by favorite she meant least repugnant. The White Room means questions, questions, questions. Questions she shouldn't know the answers to, questions she doesn't know the answers to. The Blue Hands never seem to be angry, though, only genuinely curious. Curiosity may have killed the cat, but it's the least of the Blue Hands' sins.

There are days that River doesn't remember much. Maybe because they don't want her to, because they like her splayed and half-undone, full of spaces waiting to be filled. She feels half-River, like they carved her out and filled her with parts that aren't really her own. She saw boys do it on Bedavio – taking their propulsion bikes, scraping them hollow and rebuilding them anyway they saw fit. River is a vessel to the Blue Hands, and they do whatever they like – giving her things that aren't hers, and taking away the things that were.

Maybe the memories, then, are just another side effect. Another fuckup. River sharpens her mouth around the words, tastes the edge of them on her tongue. These experiments – these people – a bunch of fuckups mucking about where they haven't the right. Steel in the brain pan, elephants blundering about but stringing like wasps.

Maybe she doesn't want to remember. If she remembered she'd probably wish it away. Maybe they've done her a favor, whether they intended to or not. But they're not playing tit for tat, and there's no sense keeping score when everyone's playing a different game anyway, never mind the rules.

"Do you have any siblings?"

It has been so long since Senna last spoke that River has almost forgotten the sound of her voice. The Blue Hands have not come for a long time, and between Senna and River there need be no words for understanding.

"My brother. Simon."

"Simon." Senna's eyes slide closed. "Simon was an apostle on Earth-That-Was. A Zealot. Martyred, and put to death by saw." She slid them back open with a purr. "Would he save you, if he knew?"

"He knows." In some deep, dark part of her mind the Blue Hands are always reaching for, River knows Simon understands her messages. Understands enough, at least, to get the ball rolling. To cause little ripples to spread across the universe and finally splash at her feet. She is as graceful as a butterfly, and Simon can be as dangerous as a typhoon given the right motivation.

From the way Senna's eyelids twitch every night, River knows she dreams. It's very difficult to fake REM, and what would be the point? As if River cares if Senna dreams or not. She's seen and heard stranger things. Dreaming doesn't make a person more human. River never feels less human than after she dreams. Meeting someone without them is the least of her worries.

River dreams of water again, of butterflies losing their wings, and she wakes to Senna smoothing back her hair tenderly. Her voice is tangled in her throat, like a Gordian knot, like she will never have it back.

"My mother once told me that all dreams are real," Senna says quietly. "Just in another place. Another time."

"In another dimension of space," River echoes. "Shoulds and woulds and ifs." All the choices you never made, the places you never went. All that you will never be. River is different in that she only dreams what will be – only dreams what will happen, only dreams of certainties and facts. River is the queen of logic in a land led by the fantastic. A puppet queen.

Senna's lips descend upon hers. It is dark, fittingly – Senna is Sanskrit for darkness. And Senna is dark. River once thought she wasn't skilled enough to read Senna's emotions, but now she knows the truth. Senna has no emotions. At least none that are human enough for River to understand.

If she looked into a Reaver's mind, would it be anything like Senna's?

"Will you come with me? Will you help me?"

River shakes her head. It is not a question of want. Simon is coming. She is the target and he is the arrow. He has been moving towards her for a long time, and to leave when he comes to rescue her is not an option. Once he is loosed nothing will change Simon's trajectory and it is pointless to have an arrow at a target that is not there.

Senna is gone the next day. No where to be found. River can feel the Blue Hand's confusion, fear, but mostly anger. It drills into her, a thousand bees stinging the back of her neck and head.

As the days pass, the anger lessens. It never disappears.

She doesn't think of Senna very often. She is too concerned with the here and now – Simon, and Serenity, and those that come with it. She senses the danger before it comes and the discord that never truly leaves. There are a thousand tiny forces at work on this ship and she has to carve out her own place among them. She must do it for herself, and for Simon.

She knows she is not making it easy for him. She loses the main thread of conversations far too easily, drawn away by far more interesting tangents – origins, perceptions, memories, possibilities, futures. Kaylee may be talking about strawberries but in her head are memories of a boy on her home planet named Ian, and how she would have married him if it hadn't meant staying home and popping out a passel of kids. Kaylee's words, not hers. Words are rarely River's, it seems. Always popping out of her mouth or jumping around in her head, but rarely hers.

Not that Simon is exactly making it easy on himself either. She tries to tell him, she tries to tell him who he should be trusting and who he should be shunning, but Simon has always had his own opinions and he always

"Took your sweet gorram time," Mal said gruffly, and Simon's answering smile was not mocking so much as knowing.

– though he ultimately forms the right ones, River notices. Long meandering paths to the truth. Making two wrongs for a right, taking three rights when he could just make a left. Yes. That's her Simon.

And it's not that she doesn't think of Senna. It would be impossible not too. River sees her everywhere. Mostly in Inara. In Inara's composure, in her steel grace, in the unflappable certainty that she is in charge of her own life. Senna was nothing if not self-composed. If not ultimately sure of her survival.

But Inara aside, Senna thinks the most like Jayne – thinks with the hindbrain, the lizard brain; ruled by the part of her that is more concerned with survival than any human emotion. Everything in black and white, and the emphasis on black. River likes to follow Jayne around just to drift in the violence, the cold sea and noise and rage. The psychic equivalent of white noise. River watches Jayne polish his guns with the same devotion Senna once showed to telling stories. River knows Jayne had sisters. She wonders if he tells good stories. Plain stories, maybe, without princes and jewels and magic, unless the jewels are stolen and the princes are limp-wristed twats in shirt coats – someone else's words again, Jayne's words, not hers - but probably good stories nonetheless. She'll ask him sometime, if she remembers and he's inclined to forget.

It's not hard to see Senna, if River looks. And River looks. Eyes clear even when her mind is muddy. River sees her in the rare blonde-haired employer, in the Gaelic rune necklaces they deliver to Taliesin, and in the lifeless, water-covered moon on the outskirts of Beaumont. River sees Senna in the precision of Simon's hands when using sharp things. She is the glint in Mal's eyes when they are about to pull off a brilliant plan, or die. She is the jump in Wash's pulse the moment between lift-off and flight. She is the devotion the Shepherd has for the Bible, the faith that he is right and no one will prove to him otherwise. She is the part of Zoë that will continue no matter what happens or who or what is gone. She is the part that is necessary. She is breathing. Senna is the part of River that forces her up in the morning, that pushed the knife towards Jayne instead of into her own chest.

Though River sees nothing of Senna in Kaylee, she knows it is not a bad thing. Kaylee is the most human person River has ever known. The easiest person to read, the only person River has ever met who feels everything. Senna and Kaylee are polar opposites – life and death, dark and light, water and oil. Senna is alien. Exotic and fascinating, even when vaguely repulsive. Kaylee is everything that is home. Kaylee is Serenity, and Senna is the cold space she moves through.

River is the branch between the two. The airlock. Deciding which she is, what she wants to be made of. Maybe one day she will realize she is a Senna. Maybe one day she will be a Kaylee. Maybe she will just be like everyone else, a glorious mix of the two.