It all started with lucythedragon's amazing and brilliant Castiel vs. Ten Picspam Poll, which, among other things, has Donna Noble winning (over Anna) for best redhead-who-bosses-him-around, and Dean Winchester winning (over Rose) for best troublesome big-eyed blond he adores.
Which left me saying "Oh, man, Dean/Donna" and then, in really quite short order it collapsed into schmoopy Dean/Donna curtainfic. Don't say I didn't warn you.
So ever since what Donna recalls as The Night of Thirty-Two Text Messages and everyone else just remembers as That Night, Donna's been a little different to how she was before. A little cleverer, a little more easily bored. A little quietly disturbed by the way her mum and granddad suddenly listen to her, as if she knew what she was talking about--but not so disturbed that she doesn't realize it might be because, a fair percentage of the time, she actually does know what she's talking about.
So Donna decides to go on a trip, to America, and while she says lots of things about big cities and shows and museums and shopping, shopping, shopping! the truth is, she gets there, rents a car, works out how not to wreck it driving on the wrong side of the road, and just... takes off. She's got a little blue card that she doesn't remember applying for and never gets a bill from that somehow never gets declined; she feels strange about using it too much, but it works when she needs it, and she thinks she needs this trip. She just wanders about--kicks her feet through sand and mud and dust, there's some quotation about dust that she can't remember--here and there, and it's sort of melancholy and her brain seems to be going on even stranger journeys when she's not paying attention. She suddenly understands exactly how trees work, from seeds to roots to leaves, and how all the roads on an entire continent connect to each other; she's never lost, even when she's somewhere she's never been before.
And when, one night, she starts seeing strange lights and hearing strange voices in the motel where she's staying, somehow she just knows what to do.
Dean and Sam arrive at the motel where all the deaths have been reported just in time to see this red-haired woman open her car door for something that is obviously not right. They run toward her, screaming at her to get away from that thing, and she smiles, waves, and starts the car--and then all the windows go opaque with hideous green-black splat.
And then the car door opens and the woman steps out, dripping, and says in an accent that's nothing like Bela's (the word that leaps to Sam's mind is cheeky; the word that leaps to Dean's mind is tits) "Well, that's done it for the deposit."
Sam says, cautiously, "Ma'am? What just happened?"
And Donna rolls her eyes and says, "Well, I needed a contained space and an ignition system, didn't I, if I wanted to get rid of that thing before it ate the children staying in room 8."
And Sam remains a little bit skeptical and Dean has hearts in his eyes. They think Donna's a hunter; Donna thinks they--and their awe, and their general state of attractiveness--are a pleasant change from most of the Americans she's met so far. She invites them back to her motel room for a bit of post-mortem, though she takes a shower first (Sam rifles her bags and finds a lot of scraps of paper with interestingly weird scribblings in them, though nothing overtly hunter-weird, more like math-weird; Dean considers rifling and gets about as far as her underwear).
She gets out of the shower, and bam, Sam can sense that there's something about her--not demon, not angel, but this woman's not just a genius or an ordinary hunter, there is something about her, something that's sideways from everything else, something different, and Sam screws up his face and says, "Dean, if I didn't--the only word I can think of is it feels alien."
And Donna says, "Oi, it's a she, and Chiswick's not that far."
Which is how Sam gets stuck driving the beslimed rental back to civilization (least they can do for her, really) while Donna rides shotgun in the Impala and flirts companionably and outrageously with Dean. And it's not that she can't sense there's something strangely twisted-up about Sam, either, she tells Dean; but she has a few graces, doesn't she, she didn't need to say it straight to him in the third person.
So Dean tells her about demons, and angels, and hunting--she seems strangely un-shocked by all of it and still hasn't slapped him for handling her bra, so it's somehow easy. By the time Donna's abandoned her car in the rental agency's parking lot, it's settled that she's coming with them, and after all her listening she's got questions.
"Angels, ghosts, demons, monsters, other planes of existence--have you ever tried to apply any scientific principles to this, or is it all just legends and mumbo-jumbo?"
And Sam makes a little Sam-face and says, "It's not exactly a scientific thing--"
"There are no limits to science, only to our understanding," Donna says sternly. "If these things can affect the physical world, and be affected by it, it's got to be possible to understand them in terms of the physical world. If the same things work against them you have repeatability. A little scientific method, a little terrifying alien genius, and we'll be in business."
Only Donna starts having these headaches--worse than headaches, almost like seizures--when she spends too much time working hard at this sort of thing. Sam says, helplessly, that it's like the alien-Chiswick-whatever-it-is is taking over and Dean says, "Can't you do something?"
Sam didn't think Dean wanted him using those powers, but Dean flails a little and says, "It's Donna. And her--alien, whatever, Sam, if you can fix it fix it."
So Sam tries, and the alien is--well, it's not a demon, he can't push at it like he can a demon; it requires control, fiddly precision, a lot of unscientific flailing and hoping, but it works. Sam can make the attacks stop; Sam can help Donna hold her own against whatever it is. And the more he does, the better Donna can handle it on her own, and the better Donna can understand what Sam is doing, what Sam's powers are.
So inside of a month or so, Donna has built the Sam Winchester Demonic Power Amplifier (with custom-designed Ruby Shutoff), which allows Sam to eradicate demons en masse from miles away just by frowning thoughtfully.
(Castiel is fascinated by Donna and mutters about nephilim; Donna points out that demons and angels are structurally very similar and if anyone gives Sam any more trouble she will find a way to reverse the polarity of the device. Castiel takes the hint, and Uriel, and gets out of their way.)
So Lilith is frowned into oblivion and the day is saved; Donna's got her headaches pretty well under control and is drawing up plans for a Ghost Energy Disruptor and is looking to be in danger of rendering hunting a fully-automated push-button profession.
(Bobby is flat-out in love with Donna's brain and her half-drawn blueprints and her scientific principles, and has informed Dean that if he doesn't treat this woman right there will be actual Hell to pay.)
Dean has hearts in his eyes and also everydamnwhere else. Donna rather adores him. He thinks she's brilliant but the idea of her being semi-alien hardly seems to faze him. He helps her build things. He is secretly a more ridiculous romantic than she is; he keeps bringing her flowers and bits of interesting hardware. The sex is fantastic.
Sam has decided to buy his own car. They can always call and meet up when Donna's going to be doing a big project and needs a spotter, right? And the rest of the time he can be sleeping somewhere far away from where Dean and Donna are.
And the world is seeming like it might be saved enough for a while.
Dean suspects that this is the part where he's supposed to have a Conversation About Feelings with Donna, and it's terrifying but he wants to--he just wants to do it right, because Donna deserves it and Dean never thought he'd get to the Dramatic Happy Ending of the horror movie of his life and he wants to get it right. But he's just sort of fumbling and hedging and Donna interrupts him to say, "Dean? Is this going somewhere good or somewhere bad?"
And Dean freezes and then says, "Good! Good--I mean, if you, um, if you want--"
Donna says, "Yes, good! I want! Yes!"
Dean says, "Really? I mean, even if--any--"
And Donna says, "Anything, all of it, yes. If you..."
And Dean says, "Yeah. Yeah, all of it."
So they wish Sam and his demon-fighting/college-reapplying Prius well and go spend some quality time somewhere quiet and distinctly unhaunted, and don't talk about weddings or honeymoons and don't make jinxy promises, and at the end of it--there having been several lovely afternoons of Dean working on the Impala while Donna tinkered and fiddled with things--Donna presents Dean with a beautifully-forged passport and a flashlight that is so much more than just a flashlight and asks him if he'd mind coming back to London with her for a visit, even though he can't carry a gun over there.
And Dean confesses that he's never left the United States and hates planes and would absolutely love to.
Donna's mum and granddad are happy to see her happy; the whole thing is going so well and friendly and nice and normal that Dean is kind of just waiting for the other shoe to drop. And then comes the time when Donna goes into the kitchen to help her mum with dishes, and her granddad corners Dean, and he figures, here it comes. The Talk.
Wilf says, "You seem like you make Donna happy, and she's a girl as can look out for herself and make her own choices, but I'm going to tell you this--she's more amazing than you could possibly know, and she's saved the world more than once, and--"
"DONNA," Dean yells, "YOUR GRANDPA KNOWS ABOUT YOUR ALIEN THING."
"CHISWICK," Donna yells back, even as she comes into the lounge, and then, "Granddad? You knew about this and you didn't tell me?" She turns and looks at her mum, who is glaring at her granddad but not looking shocked at all, and says, "Mum? You both knew I had amazing alien powers and didn't tell me?"
"He said you had to forget," her mum offers, her voice a little shaky, and still glaring indiscriminately at Wilf and Dean. "He said it would kill you--"
"I won't say it didn't give me a few headaches--"
"Donna, those were not just headaches--"
"Well, nothing my half-psychic brother-in-law couldn't manage--"
And Dean was all set to argue with half-psychic, because there might just be no one else in the fucking world like Sammy, except she said brother-in-law and Dean's on the verge of dying of happiness, so he misses the gist of a lot of the shouting that follows, except that Donna's mum is suddenly saying, "I don't know, I don't know! He might have changed his number!"
And then Donna's got her mum's mobile and is giving somebody a hell of a talking-to (well, a yelling-at)--and then there is a fucking weird noise outside and before Dean really knows what he's doing he's in the doorway with his Donna Special flashlight out, and Donna's got his back, still yelling into the phone, and then this dude in a suit is stepping out of this blue box, hangs up the phone and pockets it, and he's staring at Donna like...
Well, like she's the most beautiful girl in the world and like he might just cry.
So Dean's got a little sympathy for the guy. A little. Not enough to step back or lower the flashlight, because he did pick up on the part where this dude is responsible for Donna not knowing she's got amazing alien powers, because he took her memories.
He says, "Donna, I'm sorry. I'm so sorry. I didn't think there was any other way. I couldn't let you die."
And Donna says, "You didn't think," but most of the fury's gone out of her voice; she's down to exasperated-argument-with-Sam-when-her-h
So Dean pockets the flashlight, accepts cookies-which-are-called-biscuits, and goes out back to peer through the telescope for a while. And when Donna comes back it's obvious she's been crying, but she's smiling too, and she hugs Dean and whispers, "I saved the world," and Dean clings tight and whispers back, "Of course you did, baby, I know you did."
And then they go back to Kansas, and Dean's garage is halfway between a hobby and a front for Donna's workshop, and they keep Bobby and Sam and a growing circle of other hunters supplied with awesome gadgets, and every now and again they go out themselves to zap a few beasties. And weird people visit from far away, but Donna never leaves with any of them. And they name the baby John Wilfred Noble Winchester and call him Johnny, because Donna says calling him Jack is just asking for trouble. And he has freckles and red-blond hair.
(They name his baby sister Sammie, and her Uncle Sam never does grasp that it's supposed to be somehow an insult; she's the best niece ever, and he starts calling her just Sam the day she turns thirteen, and never goes back, no matter who claims it's confusing.)