Disclaimer: TVD and Supernatural are not mine. Title is from Explosions in the Sky (who are amazing and wonderful and you should check them out).

A/N: Really, seriously, intensely AU/AH fic here. Hopefully the boundaries of this AU explain themselves in the story. It's set around early Supernatural S4 and the tail end of middle TVD S3. (If anything's not clear or confusing, please let me know).

A/N 2: If the Supernatural/TVD real worlds ever did cross, Dean would be 13 years older than Caroline (1979 vs. 1992) and Sam would be 9 years older than her (1983). But for this story, Sam is 6 years older (1986) and Dean is 8 years older (1984).

Also I've kind of smashed the timeline together so that most of the things that have happened in the Supernatural verse pre-S4 happened very quickly after each other (essentially, there's months in between Jess dying, John dying, Dean trading himself for Sam, etc., instead of years). Finally—in the first couple of episodes of Supernatural, Dean mentions it's been two years since he's seen Sam, so I'm going with that. This fic also relies on TVD's vamp mythology instead of Supernatural, so keep that in mind.

This all makes sense in my head, so I hope I'm explaining everything clearly. Please don't hesitate to tell me if something doesn't make sense, and I'll fix it or explain my intention.

One last thing: The prologue basically zooms through Supernatural S1-3 (and early parts of 4) and TVD S1-(most of) 3. It's mostly exposition and building relationships for the actual plot. Since this is happening in the past, the dialogue is in italics. Happy reading!

the birth and death of the day

prologue

Caroline Forbes really can't remember a time when her parents had been married, much less happy together. She knows the story—Bill Forbes had tearfully come out to Liz before Caroline could form complete words, and by the time she was toddling around on her own, they were separated.

What she does remember—vividly, in fact—was meeting John Winchester.

She's five, a knee-high bundle of blonde hair and giggles, and he towers over her. Caroline remembered being a little scared of him, of his dark hair and dark eyes and how he didn't really smile—the antithesis of Bill Forbes. But he has two boys, Dean and Sam; and she always cries when Elena and Bonnie have to go home, so maybe brothers won't be so bad. And, Liz reminds her, stroking her hair, you'll always be my baby. So she cautiously accepts these new additions.

By the time she starts first grade at Mystic Falls Elementary, Liz announces that she is marrying John Winchester; and Caroline learns that it isn't that Dean doesn't like her—he's just thorny with everyone. Everyone except Sam, who eagerly slips into the role of big brother because (she learns later) he always wants to be just like Dean. Dean is the best big brother ever, Caroline, he tells her with big, serious eyes. She doesn't believe him, because Sam is the best big brother ever and she follows him around faithfully.

(Not six months later, she and Dean bond over a fierce mutual love of pie, and Sam scowls at them, muttering something about team cake.)

…..

When she turns eight, she asks Liz why John takes so many long business trips. Because, Liz tells her, pushing some of the hair that had slipped from Caroline's ponytail behind her ears, he's taking care of us. Her tone makes it clear that there are to be no more questions, at least not about John and his vanishing acts.

At ten, Caroline starts to pick up on things changing, like how her mother's eyes have slowly stopped sliding to the calendar on the kitchen wall where a small x marks every day that John is gone, and how Dean and Sam are constantly snapping at each other. The air in the house is always thick with tension; she signs up for the school cheer team to get away from it and wonders if Miranda and Grayson Gilbert would mind very much if she starts spending every weekend with them.

She gets her first "boyfriend" at eleven—Justin Andrews; and even though Dean is disappearing with John constantly now and Sam is wrapped up in dreams of college (You can't tell anyone, Care, he warns, swearing her to secrecy), they briefly unite to lean against the kitchen counter and glare at Justin while he and Caroline do math homework. Liz laughingly tells them later that in fifth grade, "boyfriend" does not mean what they think it means.

….

The summer that Caroline is almost fourteen (and she and Bonnie and Elena spend most of their days at Tyler Lockwood's pool while Elena and Matt Donovan sneak not-so-subtle looks at each other) is when the Winchester-Forbes blended family collapses and she's forced to be a little more grown up.

Anybody else would be proud of me! Sam shouts, and Caroline flinches from her spot on the front porch. She pulls her knees up to her chest. Why can't you just be proud of me?

Everyone is screaming at everyone, with John bellowing that Sam is ungrateful and going to get himself killed (which made Caroline roll her eyes, because seriously it isn't like Stanford is a serial killer hotbed—that she knows of), Dean is desperately trying to referee and Liz is shouting that Sam is an adult and if he wants Stanford, then he's getting Stanford, John!

Her heart nearly stops when she hears John say above the cacophony of voices, If you walk out that door, Sam, you better never come back. The hush that follows John's threat roars in Caroline's ears and she drops her forehead down to her knees, tears slipping down her face. She knows what's coming, remembers the fevered light in Sam's eyes when he had told her dreamily about Paulo Alto, beaches and massive scholarships. All she can hear is never, never, never.

The silence stretches on until she hears movement in the house, doors banging and then she hears Dean—Sammy, don't—and when the front door swings open, she raises her head and looks at Sam as she wipes her eyes. Sam stops, sighs and drops down into the seat next to her.

It'll be okay, Sam tells her quietly. He's just pissed. He'll come around by Christmas and everything will be fine.

She hesitates before responding, Come back, okay? He smiles at her a little and when he stands up, he pulls her up with him and hugs her tightly. Be safe, Sam, she says quietly as he leaves, his tall frame disappearing down the street.

The next morning, she wakes up to her mother telling her that John has taken off, and Dean mumbles without looking at either one of them, M'heading off too. Caroline stares at both of them, and all her emotions must be written on her face because Liz says softly, Oh honey. Dean still doesn't look up and suddenly, Caroline hates them, hates all of them because how dare they stop being a family?

Fine, she shouts, heading to the door. Leave! That's all you Winchesters are good for anyway! And she storms out, a thirteen-year-old storm of hurt and heartbreak, the door slamming behind her. She's barely made it to the mailbox when she hears behind her, Care I'm coming back. It's not forever.

Caroline blinks at Dean and says quietly, Promise? He grins and shoulder bumps her. Promise.

She's fifteen when Dean calls her from Sam's phone and tells her, voice hoarse, that Sam's girlfriend has died and that they'll both be off the grid for a little while. He tells her to ask Liz when she wants to know why, and when Dean puts Sam on the phone, Caroline wishes with every bone in her body that she was with them. It's been two years since she's seen Sam, two years of sporadic phone calls; and Dean's not much better, only popping in for the occasional holiday. She tells Sam as much, then says, Whatever's going on, just be careful, okay?

…..

Apparently 'a little while' is about three months, because she comes home from cheerleading practice to find her stepbrothers on her front porch with serious faces and barely healed bruises and cuts. It's Dad, Dean says flatly when, after worrying over them and plying them food, Liz finally asks what's happened. Caroline watches as Liz pales and her heart breaks a little because she knows despite everything, Liz never really stopped loving John Winchester.

Sam and Dean take off again, but Caroline's not nearly as bitter at fifteen as she had been at thirteen and they promise to check in regularly.

It's six months after the bombshell of John Winchester's death (and Bill Forbes has moved back to Mystic Falls with his partner Steven, and Caroline starts to think maybe this could all be okay) when the bottom drops out. Again.

The black Impala is sitting in her driveway and Dean's watching Sam pace on the front porch. That's when Caroline Forbes learns demons are real (and that one killed Mary Winchester by slashing her stomach and pinning her to the ceiling), that Sam had died and was brought back because Dean made a deal with the devil using himself as the leverage.

How long? she asks, her insides numb. How long do you have? Dean shrugs and says, A year.

We're gonna figure out how to stop it, Sam assures her and it's all just too much for a (barely) sixteen year old whose biggest worry an hour ago was mastering a backtuck.

Sam and Dean both stick closer to Mystic Falls for a while, and if Caroline doesn't think too hard, it's almost nice having both of them around all the time. Except Dean is teaching her how to shoot a shotgun with a slightly terrifying ferocity, Sam drills Latin chants into her head, and Elena's parents die in a car accident.

Caroline and Bonnie practically move into the Gilbert house, taking turns forcing Elena to eat and explaining stuff like the school's counseling policies to her aunt Jenna (Caroline is particularly knowledgeable about that one—the counselor had pestered her incessantly after John died). Jeremy just sits and stares, and the house still smells like Miranda Gilbert's perfume. In the middle of all of this, Sam tells her gently that he and Dean have to go, that there's something they need to take care of.

…..

She's sixteen (going on seventeen) and Caroline's pretty sure that this is the last time she'll ever see her oldest stepbrother. Her heart is already raw and she desperately tries to keep from crying, but when she goes to hug Dean goodbye, she can't stop the muffled sobs. They stand like that for a long time—not long enough—with Caroline almost hyperventilating into Dean's shirt and Sam looking down, fists clenched.

Hey, Dean says, pulling away slightly and looking down at her. Hey Care, you listen to me, okay? She clamps her mouth shut and meets his eyes; without an outlet, the sobs make her shoulders shake.

It's gonna be fine, Care, he says. We're gonna go fix this, okay, and then me and Sammy'll be back to threaten all your boyfriends. Okay?

She takes in a trembling breath and whispers, okay and Sam gives her a brief but tight hug before they both disappear. She watches the Impala pull out of her driveway and wishes that Mary Winchester had never been pinned to her own ceiling.

….

Sam comes back a month later, alone and thinner than she's ever seen him. She doesn't ask what happened (she doesn't want to know, wants to remember Dean as he was, standing in the kitchen and expounding on the delicacies of blueberry pie) but she does tell Sam she loves him. She makes him tea and they sit silently on the couch in the living room until Sam says, voice raw, Love you too, Care.

The Gilbert car accident has Bonnie on super-friend alert, and after Sam's been back a week Bonnie seeks her out. She's noticed the Impala is back, but Elena had mentioned in passing that she'd only seen Sam around, and Bonnie's concerned. Caroline wants to tell her so badly because she's never kept a secret for this long (mostly because she sucks at it). She wishes she could cry on Bonnie's shoulder, but Bonnie's life is normal. And even though it sometimes feels like she's the odd man out in the Caroline-Elena-Bonnie circle of trust, she loves them and isn't dragging them into this just because she could use a shoulder to cry on.

Sam lives in his old bedroom for two months, and no one goes into Dean's old room. He leaves after school starts back—she comes home from the first cheerleading practice of the year to find him gone and note on the kitchen counter that he's not going very far, and he'll be back soon.

….

She's precariously balancing holding herself together, worrying about Sam, worrying about Elena, and missing Dean when she meets Stefan Salvatore. Almost immediately, Caroline fancies herself half in love with him—we're thinking a June wedding—but he looks at Elena like she hung the moon, so she scraps that. His brother's hotter anyway, and she's not even one hundred percent sure if she's actually into Damon Salvatore or if she's just trying to fill the cracks in her heart.

Giant pieces of time start disappearing and Caroline has these marks surrounded by angry purple bruises on her neck. She can't explain where they're from, and she doesn't have the energy to come up with a halfway passable excuse, so she invests in some scarves and heavy duty concealer. She's peering in the front hallway mirror, trying to settle the scarf in the perfect position when, from the doorway, It's 85 degrees outside, Care. Sam grins at her and she squeals a little, jumping into his arms for a hug. Got a hickey? His grin is teasing, but she swallows nervously all the same.

Weird things are happening, she says later as they eat dinner at the Grill. He gives her a curious look and she goes on, Can't really explain it. Just…keep your eyes peeled. She doesn't know why she doesn't tell him about the missing time or the holes in her neck.

Damon Salvatore chooses that moment to drop into the seat next to her, all arrogant swagger and smirking. She can't explain why her stomach starts to knot and her hands start to tremble. Who's this, Caroline? he drawls, giving Sam a once over.

Sam does not like him, she can tell immediately. I'm her brother, Sam says coolly and Caroline is pulling her wallet out and dropping bills onto the table because she's pretty sure this is about to get ugly, fast. Damon smirks and looks right at Sam as he kisses her goodbye and before Sam can react, she's pulling him out the door.

I don't like that guy, Sam says as soon they're both in her car, his eyes narrowing. Something's off with him. She rolls her eyes and mumbles something about brothers and boyfriends, but if she's really honest with herself, she's not even sure she likes Damon.

….

Damon's done with her a mere two weeks after that, and Caroline is determined to drown her sorrows—shallow, useless—in the Grill's liquor supply. Sam had left the day before because he'd gotten a weird phone call from some friend of his dad's and had gone to check it out. But the more she drinks, the more she misses Dean.

Matt Donovan cuts her off when he notices she's about to start crying. He pockets her keys, drives her home and lets her cry on his shoulder. She drunkenly thinks that that was all she ever really wanted.

…..

Caroline's kind of dating Matt, Bonnie and Elena have closed themselves off from her, and Sam's been gone for a while now. She throws herself into school, into cheerleading, into winning Miss Mystic Falls; and when she wins she thinks that Dean would have had a field day at her expense. Her mom is pulling away too, saying that work is picking up and Caroline gets that being Sheriff is a big deal, but nothing happens in Mystic Falls. Well—she remembers the Gilbert car crash with a flash of guilt—nothing intentional, anyway.

It's Founder's Day and the sun is shining brightly enough that Caroline can almost forget that she hasn't heard from Sam in almost a week, that he's been gone almost a month, and that her mom isn't watching the Miss Mystic Falls float. Matt squeezes her hand in the volumes of her antebellum dress and she brightens a little.

By the time the festivities are over, it's already dark and Tyler Lockwood offers her and Matt a ride home (maybe in an attempt to make peace over some fight they've had, Caroline's not totally sure—Matt never did tell her the specifics). Later she'll wish she had said no, because Tyler crashes his car into a tree and everything hurts before she passes out.

When she wakes up, Matt has his head in his hands and Sam is leaning against the wall of her hospital room with his eyes squeezed shut like he's praying.

Sam? she croaks out and her voice is scratchy against her throat. They are on either side of her hospital bed now, each peppering her with questions—how do you feel, do you need the nurse—and she shakes them both off.

I feel fine, she says truthfully. I feel great, actually.

Matt's face breaks into a grin and he says he's gonna go call Tyler and let him know, leaving her and Sam alone.

Where've you been, mister? she asks, rubbing her forehead and frowning at the IV in the back of her hand. He shrugs. I'll tell you all about it when you're better.

Except she doesn't get better.

Caroline Forbes is seventeen when she dies at the hands of a girl wearing her best friend's face.

Game on, not-Elena says.

….

Am I evil now? she moans to Sam, whose face is white as a sheet. Are you going to kill me?

That shakes him out of his daze and he grips both of her arms tightly. No, he says forcefully. You're not evil, Care.

But I killed someone, she whispers. Sam shakes his head and repeats, You're not evil, Caroline. He pauses and then tells her, a note of warning in his voice, Don't tell your mom, okay?

She breaks up with Matt because she might love him, and she definitely hates herself—shallow and useless. She cries into Elena's arms afterwards because Bonnie (who is also a witch, Elena says gently) still isn't speaking to her and Damon's always grumbling under his breath that he should have killed her when he had the chance. Elena lashes out at Damon after that; and Stefan teaches her how to catch squirrels and to control herself through breathing. Like yoga, she says with a lightness she doesn't feel, and Stefan smiles a little.

Elena tells her everything that's been going since the Salvatores rolled into town (Caroline can't help but blame them both a little bit, since they're the reason that bitch Katherine was even in Mystic Falls) and Damon adds that they're going to take Katherine out if Caroline wants in. As if he has to ask.

The plan kind of works—Katherine's trapped in the tomb where, Damon notes gleefully, she was supposed to be all along. But they have bigger problems than Katherine now because Elena does not look like Katherine by accident.

The first vampire—the Original—Klaus, Elena says quietly, is coming and he wants the doppelganger.

….

Their gang of misfits discovers that Katherine might be the most thorough vampire ever—turning Caroline and triggering Tyler's werewolf curse—seriously, though, werewolves too? How is this real life?—to break the Sun and the Moon Curse. (Because seriously, if demons and vampires and deals made with souls as collateral are real, then hey, why not werewolves too.)

The horror of her own transition is still firmly in the forefront of her mind, so she tells Tyler she'll help him through the full moon. After all, Bonnie's finally warmed back up to her and Caroline figures it can't hurt her karma to pay it forward.

But then Elijah—who Caroline's never even met before, so she's not convinced she should trust him just because Elena vouches for his intentions—drops the bomb that the stupid Sun and Moon Curse is freaking fake. Elena explains quietly, her hands shaking a little, that there is a curse, but it's not on all vampires and werewolves like they had thought. It's just on this one vampire—Klaus, the Original, who by the way is Elijah's brother. He's a vampire, but also a werewolf and the real curse is what's keeping him from being this—this hybrid. The ingredients to breaking it are all the same, and Elena ticks them off: vampire, werewolf, moonstone, doppelganger.

She goes to Sam, because damn if they aren't out of their league with this one. He pulls out John Winchester's journal and flips through it, searching for anything that might be useful, but there's no mention of doppelgangers or moonstone curses. Sam double-checks all the windows and doors for Devil's Traps, iron, salt, the works. She doesn't know if any of those will do much good, but she has him check anyway because Klaus is really freaking scary. Caroline tells Sam he should probably head out of town until this whole thing goes down, and even though she doesn't mention Dean, she thinks Sam probably gets it.

But it doesn't even matter in the end.

Elena dies (except Bonnie and Elena's bio-dad John Gilbert find a loophole that Caroline may spend forever thanking God for). Jenna dies. Damon almost dies, except Stefan makes a deal with Klaus in exchange for Damon's life. The familiarity of Stefan's sacrifice nearly brings Caroline to her knees.

And as if their lives hadn't been completely intertwined with death already, Jeremy dies, and it's Liz who kills him because she was aiming for Damon.

…

The witches abandon Bonnie in retribution for her begging for Jeremy's life, Damon has a wall in his closet filled with newspaper clippings on animal attacks across the Southern US, and Caroline spends most of her time at Elena's. Even though she and Sam had tag-teamed Liz Forbes and convinced her that her daughter wasn't a monster, home was awkward, especially with Sam spending longer and longer chunks of time away from Mystic Falls. Plus Elena's been almost zombie-like since Stefan left with Klaus and Caroline considers it her duty as a best friend to at least try and offer a balm.

She's seventeen (almost eighteen) and damn if she doesn't feel ancient.

But then there's Tyler, and maybe they're sort of dating. Sam makes a grunting noise when she mentions it to him, so she takes that as his approval; but she waits on telling Elena. Stefan is literally ripping apart entire families.

Damon takes Elena to Chicago in a last ditch effort to get their Stefan back and when they return without him, Caroline spends two straight days at Elena's house. We'll get him back, she says soothingly, her hand running up and down Elena's spine in long strokes, the way Liz used to do when she was little. We'll fix him.

….

Stefan comes back, but so does Klaus. He kills Tyler, for some psychotic hybrid experiment; and he compels Stefan's soul right out of him. They can't fix Stefan anymore; and this time, Caroline and Bonnie both spend a week on Elena's couch.

Damon has some master plan to kill Klaus, but Caroline wants no part of it. They have a horrible track record with plans, and Caroline has to protect the people she loves. She calls Sam and leaves him a voicemail, telling him to stay where he is (wherever that is) and that she'll call him when it's safe to come back. She's starting to think maybe she should leave with him next time, because anywhere has to be better than Mystic Falls. Plus Klaus's stupid sister is trying to take over her life, and Caroline's not sure she even wants to fight Rebekah for it.

She's complaining about Damon and his stupid plans (and about Klaus and his stupid sister) to Tyler at the Homecoming that's now occurring in his backyard when he cuts her off and tells her the whole Kill Klaus plan is going down right now and he's not going to let her die.

When she wakes up later, she realizes with a flash of hurt that he had knocked her out. He tries to explain himself, but she does not play around with her free will—not anymore. Add into that the fact that she doesn't even know if his actions are his own anymore because of his freaky sire-bond to Klaus? God, Mystic Falls is the worst place for a relationship.

Elena tells her tiredly that Stefan stole Klaus's family—and Caroline blinks, because what? How do you steal someone's family? He's got them daggered and in coffins. He carries them around with him, Elena says.

Psycho, Caroline mutters under her breath and she's surprised when Elena laughs a little.

….

It's her eighteenth birthday and Sam calls her before her alarm goes off.

Happy birthday! he shouts in her ear, and she can pretty much hear his goofy grin splitting across his face. Thanks, she says. Coming home?

He surprises her by saying yes, and adds, You're gonna love my present, Care.

She smiles a little before saying goodbye and gets up, staring at herself in the mirror.

Happy birthday she says to her reflection, but all she feels is phony. Dead girls don't have birthdays. She's stuck at seventeen—a boring year that's only a bridge to eighteen. She's trapped in a filler year forever.

She can play at being normal for a little while longer but after college? Elena, Bonnie, Matt, Jeremy—they'll get married together, have babies together, get wrinkles and laugh lines together. But Caroline will always be seventeen.

….

Tyler bites her and all she can think as the pain radiates through her entire body is here lies Caroline Forbes—friend, sometimes mean girl—seventeen forever.

She has no idea where vampires go when they die, but she's holding out hope that maybe she'll see Dean when she gets there. Yeah, she thinks tiredly, she'd like to be with Dean again.

She can hear her mother's footsteps, followed by heavier ones, and she thinks groggily that Sam must have driven at the Impala's absolute highest speed because she was pretty sure he'd been in Nevada or something. She closes her eyes and says to Sam in her mind, Don't worry, I won't tell Dean. But it's not Sam.

It's Klaus and he must be here to finish her off, which in all honesty is kind of fine by her at this point. But he doesn't. To her eternal astonishment, he's almost offended when she asks if he's here to kill her. He tells her if she decides to live, the entire world will be waiting for her. He waxes poetic about beauty and her future and she's almost lost in the images his voice is spinning. It all sounds so enticing that when he offers her his wrist, she sadly says goodbye to Dean in her mind and bites.

…

When she wakes up the next morning, the gash on her collarbone is completely gone and there's a diamond bracelet on her nightstand. But best of all, Sam is in the kitchen and despite the stiffness in her muscles, she almost tackles him.

Liz must have told him what had happened before she left for work because he's immediately got her at arm's length and his eyes are sweeping over her, looking for damage. It's fine, Caroline assures him. I'm okay. She nudges at him and grins. Where's my present?

His face relaxes and he motions to the door.

Dean's smirking at her. Happy birthday, Care Bear.

…

Even though Sam tells her he's already made Dean do all of this—several times—she makes him drink three glasses of holy water, hold silver, hold iron—anything she can think of. Dean does it all good naturedly and when she's finally convinced, she's crying as she reaches for him, nearly knocking him over.

How did you get out? she asks, sniffling, not raising her head from his shirt. He smells like the inside of the Impala and tears threaten to spill down her face again.

Sam clears his throat and says pointedly, Something's happening, Care. Something really big.

Caroline looks up at Dean and he pushes his shirt collar aside, showing her.

Are those—fingerprints? She's dumbfounded.

Sam and Dean exchange looks and she says to Sam, So you've been gone so much to prepare for this Something Big?

He sighs and Dean says quietly, deep voice grave, There's a war coming, Caroline.

...

tbc.

A/N:
AAAH I hope this made sense! Please please please point out mistakes or inconsistencies (or if you're just like LOLWUT). Reviews are very much appreciated.