She awakes to smoke, alarms wailing, lights flashing. Her father's beautiful Type 95 is making that terrible screeching, crunching noise she only makes when something is really wrong. Or Delta Phi is driving. Where are her brothers and sisters? Where is her father?

"FUCK FUCK FUCK WANK CUNT BOLLOCKS" the TARDIS crunches in protest as Callista hops around, thumb jammed in her mouth, swearing with words an adolescent Time Lord should most definitely not know. She throws a lever and the crunching abates, although a small warning light begins to flash, triggering another round of violent curses. Callista tries twisting knobs, punching buttons and screaming at the Type 95 to do what she wants. Finally, after the TARDIS makes some more worrying noises, they land. The pilot has no idea where they are, and the TARDIS isn't telling her anything. Mostly it's trying to get her to leave so it can reboot in peace.

"Fine. If I die out there it's your fault. You're supposed to be cleverer than this. You're supposed to listen to me and do as I say. Not treat me like I'm 10 years old and play motherfucking nursemaid – OW! OK I'm going, I'm leaving." Callista gives the console a final, resentful look and heads out the door, slamming it on the way.

It's raining. The grass is very green, which is weirdly common for this part of the universe. Looking back at the TARDIS, Callista heaves a sigh of relief that the chameleon circuits are still operational. She's not quite sure what it's meant to be, this large white thing with wheels and windows and a little door. It has floral curtains in the windows. At least it blends it, there must be hundreds all lined up in this field. Vaguely she wonders how she will tell it apart from the rest and the TARDIS responds by putting up a little flag with her family coat of arms on it. Callista can't help but laugh, it seems so… ridiculous.

Suddenly, a door on a box opposite her bangs open and discharges two grubby, unkempt human children. They barely give Callista a glance before tearing off towards some distant buildings. So, a human planet then. Well that makes life easier. Humans don't tend to eat people that look like them. On the other hand, they could try and sacrifice her. Callista shudders at the memory.

An older human, female by the look of it, wanders out of the box after the children. It sighs, then notices Callista standing there, staring. It jumps, looking rather alarmed.

"Oh bloody hell" Callista keeps looking at it, then decides to smile. Humans seem to like that. In the back of her mind she clocks the language as Earth, English. So she's on Earth, Callista's actually heard of this planet. It's funny, she didn't think she was anywhere near the Milky Way.

"Sorry love" the human says, disturbing Callista's reverie, "You gave me shock is all. Didn't realise anyone had taken that caravan space." Caravan? The white box, of course. Callista should probably say something, humans aren't very good when you don't talk to them.

"It's okay, I… I haven't been here long." She smiles again. Humans are kind of hard to deal with, they see a lot that isn't there and more that is.

"Aww, arrive this morning did you? Bring the rain with you?" Callista looks slightly stricken, the TARDIS can't be so badly broken that it's screwing with the weather patterns can it? The human notices and softens its expression "I didn't mean anything by it love, weather's not your fault. You here with you parents?" Oh crap, a question. That she has to answer. Credibly. Otherwise there will be interfering.

"No. No… Here with my…" She looks back to the TARDIS, trying to think of a suitably cruel title for it "Godmother. Yes, my godmother. She's sleeping, long journey and all." Through her empathic link with the Type 95 Callista can sense the displeasure. There, take that.

"Oh that's nice. Well, I hope you enjoy Norfolk love, you and your godmother. Got to be off, see where those boys of mine have got to." With that, the human wanders off in the general direction of its offspring, looking a little vague around the edges. Sometimes being around the psychic circuits of a TARDIS can do that to lesser life forms.

Norfolk? Where's that when it's at home? Callista pulls out her palm unit and enters in the relevant information. It takes a little while to process, not a particularly good sign, but the TARDIS is repairing itself so not really much of a surprise. She decides to wander around whilst the computer thinks quietly to itself. It's a big field, so Callista heads off toward the farthest end from her current location. All she can see there is a fence and some sky, but it's better than standing around like an Ataxian Lemon.

She sees more humans out and about round their… caravans was it? They smile, some say hello. Politeness. She is polite back. They don't seem to mind the rain all that much; actually, they seem fairly resigned to it. That's more than a little sad; they're not an amphibious or aquatic species after all. Maybe they'll evolve soon, to make use of it. They're always evolving, humans.

At the fence the land abruptly ends and gives way to water, some hundreds of metres below. The sea. The palm unit beeps. Apparently Norfolk is in England. It's around 1998 AD, late summer. The rain is normal but will give way to light winds and sunshine in a few hours. The closest settlement is called Hunstanton, a few miles south. This place is the Windy Cliffs Camping and Caravan site. Well then. This is the Earth she starting learning about in prep school, before the war. This is the Earth that HE loves. It feels a little more like destiny that Callista is here now. Broken TARDIS and the place that HE would most likely be, the only person in the Universe that could help her fix it. The last person Callista would ever want to talk to or solicit help from. Fuck. More than ever she wishes for her brothers and father, but they are locked away, out of reach. All because of HIM. She wants to cry.

The palm unit beeps again. This time it's telling her that the TARDIS will be operational in around one Earth day. Even then it will only be able to make journeys around this solar system. The Intergalactic Buffer is completely fried. Great, stuck in the Sol System until humans come up with intergalactic stabilisation technology. The idea of hopping forwards until they manage it is really, really boring. Well, it's that or look for HIM. Hopping suddenly sounds fun.

She's halfway back to the TARDIS when she realises that she still has to wait a while to get going. Callista thinks something uncharitable about humans and then steels herself. This is going to require mingling. With the natives. Ugh. Heading towards the buildings that the humans seem to gravitate towards appears to be a decent course of action. There's nothing else to do anyway.

The first construction contains showers, toilets and laundry machines. Basic, but necessary, Callista wouldn't put much effort into decorating them either. The smell though… Next there is a room with books, some kind of transmission device, and boxes of things that appear to be primitive games. There's a chess set but it doesn't look like it's wired up. Callista makes a mental note to return to the books if the rest of the settlement has nothing else to offer. Round a corner from the entertainment room is a little shop. There are quaint little ornaments, postcards, inflatable beach implements and ice cream. These small shops are the same throughout the universe, only the pictures on the postcards change. Callista has been to hundreds of them.

The car park is a slight surprise, but then the lessons come back to her, and Callista almost laughs out loud at the idea of a combustion engine. Humans riding little explosions, how odd. More humans, but these ones look as if they would correlate with her physiologically. Adolescents. They regard Callista with suspicion. Their ages would be between 12 and 20. Young, even for humans. One of them smiles, Callista smiles back. To the west of the car park there are steps, leading down the cliff. With another glance at the adolescents, who are studiously ignoring her, Callista makes for the steps.

They're slippy and slightly green, and no wonder humans don't get very far with inventing, because they must certainly break their necks in a place like this. Surely they have lifts? Electricity? Small children barrel past, seemingly oblivious to the perils of the staircase. Time and Space, even Klum wasn't this bad. She considers running back to the little room with the books, but then the stubbornness kicks in. She doesn't want to walk back past the adolescents so quickly, they will laugh. It shouldn't matter, but it does. Callista may be a highly evolved form of life, but she's a teenaged form of life. She scoots down the rest of the stairs, on her bottom like an infant, but makes it unscathed.

The sand is a greyish colour, not like Valtos Four where it glitters in all the colours of the spectrum. Callista thinks wistfully of Valtos Four and the little café on Moonrise Beach with the scones. It doesn't rain there, the mists take care of the necessary hydration. The sea is grey too, and rough, and full of seals. The seals are hunting and playing and Callista feels a little bit like joining them, they're certainly making more sense than the small family of humans trying to erect some kind of windbreak so their fire won't keep going out. Callista kicks off her shoes and wades into the surf, ignoring the cold, listening to the chatter of the gulls. The seals eye her with curiosity, but then dismiss her, preferring their game.

The rain eases off, giving way to a patchy, blue sky. This would be the sunny afternoon then. Callista finds that the beach is actually quite pleasant in the sunshine, everything looks a little less grey. More humans trickle down the staircase with blankets and parasols and towels. Some have picnics, and the ones with the fire are roasting meat. Suddenly Callista realises that she's hungry, she last ate several lifetimes away. There's food in the TARDIS but it doesn't really want visitors right now. Being a Time Lord has perks, but not the kind that conjures money out of empty air. Time and Space that food smells good.

Shoes are pulled back on, despite sand, and after struggling back up the beach Callista is once again contemplating the stairway to hell. Most of it is still in shadow so no chance the wet patches will have dried. It might even be worse. Still, no other way back up. She is about the start climb when down come the adolescents from the car park, hands full of plastic bags which appear to be full of packets and cans. Oh good, more food, and it brought humans to witness her fall spectacularly onto the beach and regenerate into a small, embarrassed mess . The teenagers wander past her, looking curious. One of them peels off from the group. He's tall, his skin is the colour of a good cup of tea and his dark hair curls around the temples. She doesn't know why, but suddenly she is aware of male and female, and this one is definitely male.

"Er… Hi." He holds out a hand. Callista regards it suspiciously, before shaking it.

"Hello" Callista feels very odd, and small, and not human. Her voice sounds uncertain, somewhat confrontational. She can't smile.

"I'm Greg… the others thought… well, listen. We all know it's a bit shit here, and we've all been dragged down by our parents, and you look like you could use the company so d'you feel like having a drink with us? We've got crisps, and coke if you don't want beer. You don't have to, we won't be offended, you just looked lonely is all and I'm being an idiot so I'll shut up now" He keeps looking at her like she might bite him.

"Crisps? Alright then. I'm Callis… Cally." She smiles at him. Greg relaxes and leads her back to the group, makes the introductions and sits her down with a bag of crisps. The females are Gemma, Hannah and Annie. The males are Greg, Michael, Chris and Jamie. They're a mixture of ages, between fourteen (Jamie) and seventeen (Greg). Callista doesn't even remember being seventeen. She would have been tiny. There is the general feeling of all being in this together, and they may as well make the most of it. Callista munches crisps and listens to them talk about music they all like and bitch about their parents and various siblings. They don't seem to need her to talk, Hannah isn't saying much either. She's decided to tell them that she's sixteen, it roughly corresponds, she is at the same developmental level as a human sixteen year old.

The afternoon wanders on and Greg breaks out a small, disposable fireplace. He cooks burgers and sausages and hands them round. Callista tries to decline, but is told that she can buy the next lot if she feels that bad about it. Greg's parents have given him a massive holiday allowance for doing well in exams, so he can afford it. The burgers aren't properly cooked, but they're delicious and her digestive system can take it. Time Lords are tough beasts after all. Chris has stolen some cider from his older sister and passes it round. It fizzes on Callista's tongue and the bubbles seem to go to her brain. Alcohol, she's never actually tried it before. For all the Jidoon treat her like a delinquent when they encounter each other, Callista has never actually done anything remotely like this.

It grows cold and Gemma takes Michael to find some wood for a bonfire. The others smirk.

"Well, I reckon Gemma will find some wood, but she won't burn it." They laugh, and Callista is confused. Greg smiles at her.

"Mike and Gem have been at it like rabbits since they met." More confusion "They're… uh… having a lot of sex" Callista goes pink. Everyone laughs. Hannah mutters something about a poor little innocent thing and throws a packet of sweets at her. Hiding behind her hair, Callista eats sweets and listens, psychically, to them. Annie desires Hannah. Hannah desires Annie, but they don't appear to have told one another. There is a fizzle of awkwardness between them, too much unsaid. Jamie is worrying about something. Chris is intoxicated and full of desire for Hannah and that will not go well. With some surprise, Callista realises that Greg is focusing all his attention on her. She flushes harder beneath her hair as he wonders what her skin would feel like. So much desire in so little space.

Greg walks casually around the dying fire cooking thing and sits next to her. Callista looks up at him through the veil of her hair. It's silly, this shouldn't matter to her. He's human, it's actually a little perverse to be having these feelings. Time Lords do of course, but they keep it under wraps. It's something you're taught to control because otherwise things get messed up and you can't do your job. Just look at the humans, they can't get anything done because they're constantly distracted by desire.

"Hey, I'm sorry. Didn't mean to make you feel uncomfortable." He puts a hand on her shoulder.

"It's fine, really. I'm being… silly I guess. I don't really socialise much. Usually it's just me and the… my godmother, travelling, so I…" Babbling, good, that will most certainly help things. The hand, the physical contact, has amplified the psychic link. Her empathic abilities kick in and suddenly her stomach is full of angry vespaforms and her breath catches. Do they feel like this all the time?

The palm unit beeps from Callista's pocket, worrying about her heart rate.

Gregory Johannson, Greg, is seventeen years old. He loves physics, Oasis and girls. Right now, on this miserable camping holiday, he is falling in love with an alien decades older than himself. Cally. She isn't like anyone else he's ever met. She doesn't move like the girls in school, she's confident and settled into her skin. Her face isn't caked in make-up or spots and her eyes. Oh god her eyes. It's like he can see stars in them, nebulas, everything. When she looks at him he sees the universe. Then, when she meets his eyes and blushes, it's as if she knows exactly what he's thinking. Greg can harldly concentrate on being cool. When he puts his hand on her shoulder she leans in, and something goes beep in her pocket.

"Sorry… erm… mobile ph… pager. I'll just…" The girl, Cally, stands up abruptly and wanders off fiddling with something from her pocket. A pager. He's never met anyone who actually owns a pager before. Greg's reverie is interrupted by Michael and Gemma wandering back into his line of sight. They both have bundles of driftwood under their arms and only look slightly more ruffled than when they left. Cally stops fiddling with her pager and helps with the fire. Soon enough they are all huddled round a crackling, green blaze laughing and joking. Somehow Greg finds the courage to put an arm around his strange new friend and she cuddles in, her hair tickling against his neck.

The night wears on and Greg finds that Cally loves astro-physics just as much as he does. She knows so much, more than anyone he's ever spoken to before. Her eyes burn into his as she explains a concept that he's fairly sure even NASA haven't come up with yet. Somewhere along the way Hannah and Annie disappear. Chris has passed out and Jamie makes his excuses and wanders back to his caravan. Around 3am Greg looks up to find that Michael and Gemma have also dematerialised and it's only him, Cally and a snoring Chris left around their fire.

Callista barely knows what she's doing when she pulls Greg back to face her and kisses him. All night she's been becoming more and more lost in the experience of him. His love for space makes him seem out of place on Earth. He was meant to born on Gallifrey, of this she is completely certain, his consciousness must have become lost somehow and landed on this odd little planet. She's probably telling him far too much but it's beautiful how he swallows every concept and understands it almost immediately.

His lips are odd, damp and soft, but good and Callista wants more. Stopping to breathe is a pain. Greg's teeth graze her mouth and she moans, almost surprised when he echoes her. There is something so beautifully selfish about these feelings and Callista almost feels guilty until she remembers that he has them too, and he's responding, so it feels good for both of them and they can both be selfish. Suddenly the kisses aren't enough, Greg's mouth is such a small part of his body, and Callista wants to see what else will feel good to kiss. Clumsily making the journey across his jaw, she works her way down his neck to the top of his jumper. The wool is in the way and Callista tugs, making little noises of frustration.

He can't quite believe this, none of the girls from school or the park have ever been quite so into Greg as Cally is. It's like she doesn't feel shame, or self-consciousness, she doesn't seem to be aware that most people would be shocked by how quickly she's giving it up. There's no time to even think about how he won't complain though, as she's tugging his jumper up over his head, taking the shirt with it, and tracing hot lines over his shoulders and chest with her lips. All at once Greg is on his back in the sand, arms pinned to his sides, as she kisses and nibbles her way all over his stomach. He's on fire, she's burning him. All the while she's making these little growling, moaning noises and Greg finds that he's answering her with little noises of his own. Not once in his short history with women has Greg ever made noises. Or had them made at him. He's always been told to be quiet, been afraid of being discovered, felt ashamed for wanting what he wants.

Callista doesn't care that she's feeding the fire. With every wave of desire from Greg, her own builds and crests back into him, a cycle that never ends. There must be a crest, an end to this delicious agony, but all she can feel is this deep, thudding song, demanding fulfilment. Her clothes become too warm, too limiting, constricting, and she rips off her jacket and rips her shirt in the effort to be free of it. In her haste, Callista has freed Greg's hands and they move to her breasts. Tentative at first, he gains encouragement from her moans and begins to knead and massage them as she arches above him. Why has Callista never done this before? It feels so damn good. Everything about it is beautiful and intoxicating. Greg's mouth finds hers again and they roll together, skin on skin, trying to devour one another.

Trousers, they are a problem. They have this thought as one, so connected now, through chemicals, psychic and empathic links, deeper things that Callista would know to avoid if she'd ever been to school on Gallifrey. They help each other escape the unnecessary and irritating bindings of jeans and cords respectively. Greg slips a finger between Callista's legs and up inside and she almost gives in to the waves right there and then, except for the knowledge that there is something better. Her hand finds the better thing, so hard that it hurts, and rubs it, almost in vengeance. To pleasure one another gives each pleasure and for a few moments they are lost in these touches, still except for their harsh breathing. Then Greg begins to move his finger again, soliciting harsh gasps from Callista as she grips his shaft harder in return.

At some unknown signal it becomes too much and he climbs between her legs. In the predawn light they gaze into one another's eyes as Greg guides himself inside her, slowly at first, but then gaining momentum. Callista cannot move for the sheer, agonizing, beautiful, massive feeling. There cannot be anything better than this. She shifts and brings her legs up around his back to hold him to her for just a moment before he begins thrusting. With each push their cries become louder, harsher, more frantic. Greg pushes one of Callista's hands down to her clitoris, urging her to rub, to bring herself off with him. It doesn't need words, she understands. The come, together, and collapse into the sand.

The sun finds them intertwined, dazed, with the seals looking on curiously. All too soon they are interrupted by the calling of the gulls and the early morning cold. They pull clothes back on, and check that Chris is still breathing. Noticing the sticky mess on Callista's thighs Greg begins to panic.

"Shit!"

"What's wrong?" Callista is genuinely confused, is there etiquette here she hasn't observed, something to do with semen? She was just going to dip into the sea to wash it off before putting her trousers back on but Greg is looking at it like it's going to bite him.

"We didn't use a condom. Are you…? Fuck, I'm sorry, I'm usually better at this. You caught me off guard. Oh crap." He's gone a funny colour, and seems to be trying to say something else, but Callista cuts him off.

"Oh, birth control? No, that's fine, I can't get pregnant by you" She smiles, in a way that she hopes is reassuring.

"Are you sure? Why not?" He's still panicking, he doesn't believe her. How curious.

"Because I'm…" Callista almost says "not the same species as you" but quickly remembers herself and says "On birth control. A drug. That stops it. You have those here don't you?"

"Err yeah. Sorry, just panicked. My dad would kill me if I got someone pregnant." Greg sits down and slips on his trainers. His socks have made a break for freedom, probably appropriated by gulls. Callista wanders into the sea to clean off. It's still fucking freezing but it feels good, stopping the encroaching stickiness. Greg watches her bottom as she wades out, temporarily mesmerised by the movement. She's really nothing like any other girl he has ever met. Perhaps she's an alien.

June 2002

Greg is graduating from Cambridge today. A first in Theoretic Physics with a masters placement, his parents are so very proud. He's come a long way from their cramped flat and camping holidays, and he'll go even further. Today should be vibrant and beautiful, he has his whole life ahead of him.

All he can think of is her. Where did she go?

Siblings, grandparents, aunts and uncles all come and go in a blur. They go for a meal, far too expensive for his family but they're all so happy and Greg can't ruin it by thinking about just how much it's costing them to do this. He feels so ungrateful for not concentrating on them. It's been like this on every major day of his life since the beach, every key event makes him wish for her. She should be here.

Cally.

After she'd dried off, they'd headed up the steps, and to a café across the road from the caravan park. He'd bought breakfast. They'd chatted, kissed, joked. It was so perfect. Then her pager had gone off and she'd had to leave, saying her godmother was wondering where she was, she'd see him later. They'd arranged to meet at the toilets at eleven, Greg was going to drive them somewhere. It didn't matter where, they were just going to be together. She never came. He'd searched the caravan park, the beach, the café. Hoping.

It faded, but it never quite went away, that hope. Women noticed it, and they left, and Greg never cared. His work progressed, he was the best in his year, the kid from the council estates. The tutors had such high hopes.

They are leaving the restaurant when he sees her. Same jacket, same shirt, same cords, same hair. She's running. Greg tries to call out but his voice sticks and the tides of relatives envelop him again. She's gone.

October 2010

As Greg presents his thesis he's aware of that feeling again. The loss, the sense that someone is missing from this moment. There's no title for it right now, the thesis, but it's ground-breaking. It could change the face of modern physics. It's about time travel. As Greg talks, and the great and good of the scientific world listen, he scans their faces. Seeing only approval he is about to go back to the slides when his eye catches on a familiar mop of hair. Looking down, Greg cannot allow himself to be side-tracked with these stupid hallucinations again. The paper is finished, there is a rousing applause. There is talk of prizes, and a man in a wheelchair gives him praise in an electronic monotone. Greg slips away to join a figure in the courtyard.

"I'm so sorry" She hasn't changed. Her clothes are the same. Everything. The burn from the dying embers of the fire is still on her sleeve, the hems of her trousers seem to still be damp from sea water. And here he is, Dr. Gregory Johannson, soon to be a Professor, prematurely grey, thin, sad. Old. He is struck dumb by the sight of her.

"I got lost you see, some of my circuits weren't in the right place. Finally sorted it out but I was too late, and it turns out that you're a fixed point. Who knew?" She looks at him, really looks at him now, and there's a ghost of pain in her eyes. He can't hide the anger, shock and hurt in his, because somewhere he's still seventeen and waiting for her all day in the rain.

"Your theorem, it has a name you know."

"What?" His first word to her in twelve years, and it's choked, small. Twelve years and she hasn't changed at all.

"It's called Callista's Theorem. I was named after it. Well not quite, but my parents couldn't think of anything else. It's like being called Jane Smith here."

Gregory cannot cope. He turns and walks away from her, back to the scientists, and the prizes, and the empty life.

Quietly, Callista says again

"I'm so sorry"

He doesn't hear her.