Disclaimer: They're not mine, I just borrowed them.

Summary: AU of season 5, veering off from canon after the end of 5.04, after Sam and Dean are hunting together again. In a diner one day, Sam notices that something's missing. Something kind of important.

Written for the 2014 Sam & Dean Mini-Bang at samdean_otp, although clearly my Muse does not comprehend the concept of "mini." Art by mashimero at the LJ.

Anosmia

He's not sure exactly when it starts. He doesn't notice anything until one day in the car when Dean wrinkles his nose and grumbles, "Oughta be a law about leaving dead skunks on the highway."

Sam frowns. Dean is reacting to something, that's clear enough—Dean's ew that's gross expression really can't be mistaken for much else. But Sam doesn't smell anything, eau de polecat or otherwise, and for Dean to be reacting to it at all, given their line of work, that has to be one powerful deceased skunk.

He files it away for contemplation later, when he has the time. They do have an apocalypse to stop, after all. Maybe it's like one of those mystery noises the Impala periodically makes, the ones Dean swears a deaf man could hear and that Sam privately (very privately) thinks are just proof that his brother's relationship with the car is completely and totally unnatural.

Some miles later, they pull into a diner for lunch—fancy, by their standards; a place with an "A" on the inspection placard, floor tiles that are beige because they're supposed to be, not just patinaed with grease and dirt, and actual security cameras rather than obviously plastic fakes—but the prices advertised in the plate-glass windows are dirt-cheap even for a small-town diner, which is an important consideration since they're scraping the bottom of the Winchester bank.

It's when Dean does that overly-appreciative inhale that he does when presented with a delectable food aroma that Sam realizes that he really doesn't smell anything. There's no scent in the air at all—not the chili that is apparently the Wednesday special, not the asphalt of the parking lot baking in the sun, not even the standard reek of old grease and questionable customers that fills any diner like this. He might as well be standing in a hermetically-sealed room.

Maybe the skunk hadn't been the olfactory equivalent of the Impala's mystery noises, after all.

There had been that case of sniffles back in Ohio... The pollen counts had been through the roof, and the stress of knowing Lucifer's out there wanting to take over your body probably isn't good for the immune system, so—figuring it was allergies or an oncoming sinus infection—he'd tossed down vitamin C and knockoff Sudafed until he could breathe without sneezing and gone on with his miserable life. But that had been three weeks, seven states, and five cases ago.

And besides, if the problem had been an overdose of allergens, why is he standing here listening to Dean rhapsodize about the way Wednesday's Never-Ending Kettle of Chili smells, completely unable to tell if it actually smells that good or if his brother's pranking him?

After a few minutes, he's pretty sure it's not a prank. Dean doesn't drool for pranks.

He slides into the booth opposite his brother as Dean flirts with their waitress (Hattie, according to her name tag), going so far as to compliment the odd-looking charm she wears on a heavy silver necklace (it's either a horned cow's head or the worst rendition of the Minnesota Vikings logo ever). Sam looks out the window, ignoring their banter in favor of trying to remember what the last thing he actually smelled was, and before he realizes it, Dean's ordered for both of them. (Chili.) Is he even going to be able to taste it? Smell plays an important role in taste, he knows that much, and if he really can't smell, he should have noticed it long before now.

But food has tasted off to him since his first taste of demon blood, to be honest. Even more so since Lucifer was freed, as if just knowing that the Devil wants him for a vessel is screwing up his senses.

He sternly corrects himself on the passive voice: Since I freed Lucifer. Denying responsibility just compounds his sins.

The chili arrives, and he tests a spoonful. It's not entirely tasteless, but it doesn't taste like chili to him. It's more like a blast of saltiness across his tongue, with a little bit of sour and sweet and bitter—the basic things that taste buds pick up. No spice or subtlety at all.

Demon blood only dulled the taste of real food. It never did this.

"Sam? You gonna eat that or meditate on it?"

"Huh?" He looks across the table at Dean, who's already inhaled half his bowl and is looking at Sam's with the same expression of lust that he was aiming at Hattie's ass ten minutes ago. "Nah. You can have it."

"You okay?"

Sam shrugs, pushes his bowl over to Dean, and flags Hattie down. "Not in the mood for that much spice, that's all." Something bland, something that's not supposed to have flavor, so that his brain isn't demanding to know where the food is because what he sees doesn't match up to what he tastes. He convinces Hattie to tack his bowl of chili onto Dean's order, so they're not paying for an extra special, and winds up with meatloaf and mashed potatoes. When Dean's not looking, he buries them in enough salt to settle the spirits of a whole herd of dead cows. The taste of salt helps convince his brain that he actually is eating, at least until his stomach is full. He can't afford not to eat, neither one of them can; they both have to keep their strength up, even on the days between jobs. With their luck, the day they skip a chance for a meal is the day they'll wind up fighting Heaven and Hell, and somehow Sam doesn't think Lucifer or Michael will let them stop for a snack.

At least he knows what he'll be doing tonight: research. Something caused this, and he needs to fix it, quick, before Dean figures out that something's wrong. That's just what he needs, Dean having to nurse him through some wacky nasal issue during pending Apocalypse. Dean's temper is short enough these days, between the booze and the frustration and the anger. Something happened while they were separated, something that Dean won't talk about—and whatever it was, it makes him even more pissed off at Sam than he was about the whole trusting-Ruby-more and setting-Lucifer-free mess in the first place. Sam's thought about asking a thousand times, but he hasn't yet managed to scrape up the nerve. Especially after the way Dean exploded when Sam mentioned the possibility of checking out a rare-book shop in Detroit.

Honestly, he's not sure he wants to know. Finding out that Lucifer wants to wear him was bad enough.

Dean demolishes four bowls from the Never-Ending Kettle of Chili plus Sam's, possibly ending that promotion for good, and gets Hattie's number and a free slice of blueberry pie in the time it takes Sam to choke down his own plate of salt-crusted food. As they get in the car, Sam reflects that maybe it's a good thing his sense of smell picked today to go dead, because otherwise, an afternoon in a closed space with his brother after that much chili could be downright miserable.

If the chili wasn't enough of a sign, the motel that night is; there's no mustiness in the air, even though Sam can see the mildew in the bathroom and the mold in the corners and the water damage to the ceiling, and Dean makes a noise-movement-something at the door that might be a half-suppressed full-body flinch. "Don't look too close at the carpet, Sammy," he says, tossing his duffel onto a bed and digging out the salt. Sam looks anyway, and regrets it.

"Haven't had a chance for new plastic in awhile," Dean says while he's drawing the lines. "Got cards waiting in a box in Omaha if we can get there." It's an apology, like the sorry state of the room is somehow his fault.

Sam gives his own bag a toss, and sees the ashtray on the nightstand. It's been ages since they were so hard up they stayed in a smoking room. Dean doesn't like the stink of old tobacco any more than he does; it adheres to your clothes like cat hair and warns every supernatural creature with a working sense of smell that you're trying to sneak up on it. Normally, they would have gone on and found a place that had a non-smoking room available, but their strained finances aren't going to let them be picky tonight. They have to eat and the Impala needs refueling.

Maybe this explains why Sam hasn't noticed anything before. Shitty motel rooms, rotting corpses, burning flesh, boiling blood, a thousand different kinds of noxious goo... In their line of work, being unable to smell is a blessing, not a curse, and if allergies make you go congested without turning into a full-on sinus infection or sneezing fits, spring's your favorite season. Nobody ever gets fully inured to the stinks they deal with. Just a couple of weeks ago, Dean—a man who's been to Hell—hurled from the stench of a monster. And that's not even counting the normal smells of sharing close quarters with another human being.

But he's not sick, not obviously. Not even the sniffles. So this has to be a sign of something else, and that's what worries him. For all the demonic and angelic crap in their lives, they're still human, and humans are fragile creatures. Humans get things like—say—brain tumors. That might even be why Lucifer's so convinced that he'll say yes, because it's not like he and Dean have any access to chemo or radiation or brain surgery. If there's something growing in his head, angelic interference might be the only way to heal it, and with Cas's powers waning...

Sam settles at the table with his laptop while Dean's in the shower and pulls up Wiki. The page on the sense of smell—olfaction—is highly technical and less than helpful, except for telling him that the lack of a sense of smell is anosmia. Unfortunately, in the medical world, just having the name of something doesn't always help. Demons, now, demons you can exorcise with that info.

The list of things that can cause it is three screens long and incomplete, and that's just the physical causes, because scientific pages on Wiki generally do not include supernatural causes of mundane illnesses. Not unless the teenagers have been making edits again.

He digs out his notes from the last few weeks. Most of his recent research has been Biblical, notes on the thousand and one versions of Revelation and the assorted folklore surrounding Lucifer, Michael, and Armageddon, but they've been taking the odd regular case, too, if there's such a thing as regular in their lives anymore. Werewolf, chupacabra, something that was supposed to be a coven of witches but turned out to be some bullied teens with too much mascara and no limits on their Internet access. Nothing powerful or vengeful enough to have done this. There's the angels, but only Zachariah has shown any evidence of subtlety or imagination. (Sam still owes him for that tech support gig, real or not.) Lucifer's probably better at the subtle, but he's also totally convinced that long, heartfelt dream-conversations and attempts at puppy eyes are going to be enough to pull Sam over to the dark side, so why would he bother with something like this?

And either way, wouldn't that require that the angels be able to find them? The sigils carved into their ribs seem to be working. They still have to use a cell phone to contact Cas, anyway, and the only times they've had to deal with other angels, they've pretty much walked smack into them.

Sam stifles a sigh, pulls a beer out of the cooler, and goes back to the laptop. (The beer has no taste whatsoever, but the stuff in the pipes came out rust-brown at first.) He'll just have to go through all these possible causes and see if something fits. Probably none of them will, but at least it's a bit of variety from being up to his ears in angels and demons.

Seriously, though, the last time something major turned out to be an actual non-demonic, non-hunting health problem was... The measles when he was six? Maybe? And he wouldn't have had that if Dad hadn't been so focused on hunting that he forgot their vaccinations.

He's too young for Parkinson's and most of the dementias. Multiple sclerosis? Still on the young side, but not impossible.

Head trauma. Now there's a possibility, though it's been a good long while since he got anything even approaching a concussion. He doesn't remember taking a hit to the head recently, but then, he's not sure when this started, either. Smell's one of those things that you take for granted. He can't be expected to remember when he stopped noticing—

Wait. He definitely remembers the bar—the sharp tang of the endless limes and lemons he'd cut, the bleach-and-soap steam from the dishwasher, the rich black aroma of the demon blood when Tim and Reggie tried to force him to drink it. Even if God (or whoever) did smack him into instant sobriety, the addiction's still there. The iron-copper-sulfur smell of it is so clear in his memory that he can almost smell it now, just like he remembers how he immediately wanted nothing else, remembers the way part of him didn't even care if there was a knife to Lindsey's throat so long as he could taste that blood, that power again—

"Everything okay, Sam?"

He jumps half out of his skin. Instinct and habit send his fingers flying across the keys to swap to a browser tab on translating Aramaic before Dean can get a good look at the screen. He's not sure if Dean intentionally startled him or if he was really just that lost in his own thoughts. "Fine. Just trying to translate some of this stuff Bobby sent me."

Dean looks at him, that look that's never quite skeptical but is also completely unconvinced by Sam's statement, that look that greets everything Sam says these days, until he finally shrugs. "Don't stay up too late," he says, and goes to bed, the one next to the window, closest to the door. Even now, that's always the one he takes, putting himself between Sam and any threats.

Sam pretends to go back to reading his screen, but he waits for it, watching. There's no neon outside this motel, just a plain lit sign and streetlights, and the curtains are thick enough to block it out—

Dean's hand sneaks out from under the bedspread and tugs back the drapes, just a bit, just enough to let a thread of light from outside fall onto his bed, and then he rolls up in the covers and plants his head on the pillow, just like nothing happened.

Sam figured out the nightmares pretty quick—takes one to know one. The hypervigilance took a little longer, but still, a guy goes to Hell and comes back, you expect there to be side effects. This, though, this didn't show up until after the angels' idiot plan to torture Alastair failed so very spectacularly, after Dean found out about the first seal. It took awhile to notice, because Sam had other things on his mind and Dean's always been good at covering his tracks if it's something he thinks will make Sam worry, and even then, the first few times, Sam was convinced he was seeing things.

Because Dean may be the first one to tell people they've got every reason to be scared of the dark, but Dean's also always been half a creature of the night himself, the one who was more alive after sunset and not just because that was when all the bars were open. Darkness, in and of itself, never scared him. Sam remembers more than one stormy afternoon squandered in the pursuit of seeing just how dark they could make the inside of a blanket-fort. He was always the one afraid to sleep when the power went out at night, the one who required funny stories and flashlights and constant contact with Dean.

Now Dean's as quick on the draw with flashlights as he is with guns, and to sleep, he needs—

Okay, so Sam's not brave enough to call it a "nightlight," even in the privacy of his own head. Dean would beat the ever-loving crap out of him.

It never happens in rooms where there's some light inside, where the curtains are worn so thin or full of holes that half the light from the parking lot shines through anyway. It's only when they're in places that can actually be made darkest-dark. Dean finds excuses to go to bed before Sam, and if there's no way Sam will believe the excuse that Dean's just that tired, he'll turn to his trusty pal alcohol, just to make sure he passes out before Sam turns out the lights.

Dean will only risk the blackness if the light outside is red. If they land in a motel that supplies alarm clocks, if its numbers glow red, Sam knows if he leaves Dean alone, just for a couple of minutes, he'll come back to find the clock shoved into a drawer with the Gideon Bible and Dean already trying to paralyze his terror with a bottle. Green or blue displays, Dean ignores.

Ember-red, blood-red in the darkness, and Dean doesn't just have nightmares, he comes out of bed with a weapon in hand, trying to defend himself from memories. So far, he hasn't done more than put a hole or two in a wall. So far, he hasn't mistaken Sam for a demon, though that's largely because Sam's a light sleeper these days and when that kind of noise wakes him, he freezes, afraid that movement will get Dean's attention.

It's clearly Hell-related—some kind of PTSD, like they both don't have enough of that already—and this is so not what they need. That's why Sam hasn't mentioned it, why he hasn't started shoving the clocks into drawers on his own, because if he does, Dean will go into full-on denial and try to prove it's not happening, try to prove he can sleep in the dark, and probably wind up so sleep-deprived that he does kill somebody. Sam just silently does what he can—stays up later doing research, mostly, because Dean never complains about the room being too bright anymore. When he can get away with it, Sam "accidentally" leaves the bathroom light on, or one of the lights over a sink. Once, he even "forgot" to give a microwave door the final push to make sure it latched. Anything to get a bit of light shining through the black.

Because Dean needs to be able to get some rest, and he needs to be able to get it without relying on alcohol. Drinking himself to sleep every night is a bad plan, not just because it's the first step to liver failure, but because there's only two people in the universe who stand a chance of getting them out of this mess, God and Dean. Since God doesn't seem to care, their chances are better if Dean's at least mostly sober.

Sam has no illusions. Not any more. If he actually proves to be useful, it'll be as part of somebody else's plan. Every time Sam tries to fix this disaster, he just gets them pulled in deeper. It's been that way ever since he promised to save Dean from Hell. Nobody else will admit it, not to his face, but the truth is, they're all just waiting for Sam to fuck up again, to give in to Lucifer and say yes and kick-start the final phase of Armageddon.

And what's he doing? Staring at a screen trying to figure out where his sense of smell's gone.

Had it started with Lucifer? That first night when Lucifer came to him in a dream and told him why he'd been targeted by Azazel? It doesn't seem right, but it had to be soon after that. When he and Dean decided they'd be better off fighting it together? He closes his eyes and tries to summon the memory.

No. He had definitely been able to smell then. That car he'd stolen had reeked of smoke, and not just tobacco. Since then.

So much else has been grabbing his attention that he's never going to figure out when exactly it happened, not more specifically.

He should tell Dean in the morning. Maybe it's nothing, maybe for once it actually is a purely physical ailment, but it's still a potential weakness, and Dean had made it clear: No more lies.

But—it's smelling things, for crying out loud, not like he's actually sick or suffering a demon-blood relapse. A lot of the things they hunt rely on smell, but their own training focused more on sight and sound, because a human's sense of smell is relatively weak compared to everything else out there. Even Dad never expected them to track a ghost or skinwalker by smell alone.

And if he does tell Dean about this, what's to stop him from assuming that this is just some other scheme of Lucifer's? That it just means Lucifer's already gotten his hooks into Sam and Sam really can't be trusted? Dean could make them split up again, or pack Sam off to Bobby's—or Bobby's panic room. Sam's been locked in there more than enough for one lifetime, thanks.

No, supernatural or not, he's better off trying to figure this out himself.

Sam glances up at his brother, at the just-barely-opened curtains.

One of them should get some sleep.