He'd almost killed Sam.

Dean had almost killed Sam, without a second thought. He'd stared straight at his brother and seen nothing but another monster to slay.

Dean pressed the heels of his hands to his temples, squeezing his eyes shut.

Sam hadn't raised a weapon in his defense, merely relying on the promise that Dean would break out of the Mark's haze. He couldn't think about what he'd do if he hadn't…

Why did he let Sam come along for this hunt? Then again… Dean wasn't sure what would've happened if Sam hadn't been there.

Sam hadn't even said a word, afterward.

Dean shook his head, rubbing his eyes. He hadn't realized how severe the Mark's demand had become. Within seconds, he'd succumbed to its rhythms, his blade cleaving flesh and bone, his vision hued in the crimson of the blood he spilt. His quick, brutal strikes hadn't been fueled in anger. It wasn't rage, it wasn't thrill; at its heart, it wasn't even enjoyment. It was utter calm. He'd been flooded with the emotion of a machine performing its task. Simple peace, stronger than any he'd felt before, spare for when the First Blade was in his grasp.

There was no question, no contemplation, no morality or indecision. It was pure. For a few moments, his path and purpose were clear, his body and mind unified beneath a singular drive: kill.

He forced himself to release a shaky exhale, wringing his arm as though to jar loose the Mark's hold. He couldn't afford to lose himself in it again—not now, not ever—and he couldn't afford to dwell on it; they had to keep moving.

He shoved down the thoughts and glanced about the room of corpses, about the blood splattered across the walls, across his own skin and clothes, pooling on the floor. His lip curled in disgust. He'd encountered gore plenty in their line of work—he'd even been neck-deep in it more times than he could count. Yet, despite it all, blood remained repulsive. He wasn't afraid of it by any means, but he didn't like how it clung to his skin—he hated whenever flecks landed in his mouth; he'd always spend the next hour trying to spit out the iron tang. He couldn't understand how Sam could stand to chug the stuff—much less how he could want to.

Dean nudged a corpse with his toe, ensuring the head had been fully severed.

Then again, Dean had spent a night as a vampire himself. At the time, the pulse of a heartbeat drove him mad. The stench of the sweet, coppery blood. The faint blue lines of veins through flesh. The hunger had consumed his thoughts—it was all he could think about. He'd almost hurt—or maybe even killed—those he loved for its sake.

He'd been so close to giving in, even after he knew it'd ruin his chance at becoming human again. It almost hadn't mattered, because the smell had promised him the taste would be worth it. The raw, gnawing pain in his gut had threatened that a cure wouldn't matter if he didn't feed, because he needed it more than the air in his lungs.

Luckily for him, there had been a cure—even one that tasted like puke. He knew he wouldn't have been able to resist much longer. Within a mere few days, he'd have either convinced a hunter to take his head off, or his fangs would've been deep in some poor soul's throat.

At the time, he'd fantasized that the blood tasted sweeter than honey, and he'd wanted to drink it by the gallon. But he'd been a vampire, then—his very biology had changed; he hadn't been human anymore. Sam, on the other hand, he… Dean trailed off, shaking his head, unwilling to conclude the thought.

Is that how it was, for Sam, though? Is that what it felt like? Was he fighting that same, screaming hunger in his skull? That same, gnawing pain in his gut? That same, relentless need that wouldn't abate, no matter how madly he tried to shove it down?

Dean gritted his teeth. He wished there was some potion Sam could drink to cure him of his curse—no matter how awful it tasted, how terribly it hurt. And he knew Sam would do almost anything to break free of the blood's hold, too.

As he glanced over the vampires, Dean couldn't help but muse if there was a reason Sam chose this particular hunt. Was it merely the nearest one to his supposed lead on a cure for the Mark? The first, simplest thing he'd found? Or was it intentional, the selection of vampires? Maybe it was a subconscious decision—maybe… maybe he couldn't help but want to kill something not far from what he'd become.

Dean crushed the thought, wiping a hand over his face. He should probably check on Sam—the kid often took the deaths of the more human monsters hard. Maybe it shouldn't be surprising, why. Or maybe it wasn't that at all, Dean noted silently; maybe he just wanted space, given that Dean had almost killed him.

Either way, they couldn't afford it, though. They had a lot to clean up, else they risked someone finding a freakin' massacre. It was a kind of attention they didn't need right now, if they ever did. He started down the ladder slowly. They'd do what they could inside, first, then deal with the bodies after dark.

"Sammy?" he called as he ambled toward the door, machete still in hand. He slipped through the crack of the doorway, squinting in the gleaming sunset—then froze, heart stilling instantly.

Sam stood alone, his back turned to the warehouse, with four bodies at his feet, swimming in a sea of blood. At first, though surprised, Dean might have thought they were merely other vampires, whom Sam caught returning to the nest. But in Sam's twitching hand, the demon-killing knife glistened, dripping with blood, and the wretched stench of sulfur poisoned the air.

Sam began to glance back, but Dean didn't wait for him to turn. He grabbed Sam by the shoulder, yanked him around, and shoved him violently against the side of the Impala. Sam didn't resist in the slightest, seeming dazed. Dean dug his arm into his brother's chest, still gripping the machete and shouting, "The hell did you do?"

"Dean, I didn't—" Sam started, voice strained, eyes panicked.

"How much did you drink?" Dean shoved him roughly, causing the car to rock beneath the force. Before words could fall from Sam's parted lips, Dean jarred him again, "Don't you dare lie to me."

"None, Dean, I swear," Sam replied hastily, the tremble of his voice mirroring that of his body. "I didn't drink any."

"Stop lying!" Dean shouted in his face. He'd agreed to let Sam join the hunt; he'd left Sam alone for minutes, and his little brother had betrayed his trust with a relapse at the first opportunity. "How much, Sam?"

"Dean—listen to me," Sam slowed his words as much as he could manage—which, admittedly, wasn't much. "I didn't; I didn't—I swear."

Dean's eyes searched Sam, anger and worry still roiling in his chest. But, he realized faintly, there was no stain of blood on Sam's lips, no trace of crimson on his teeth. His skin, his clothes weren't blood-free, but they were probably cleaner than Dean's. His gaze flicked back up to Sam's eyes—desperate and anxious, but he couldn't catch a wisp of deceit.

Maybe he wasn't lying. But all he'd said was that he didn't drink it.

"You shoot it up, then?" Without waiting for an answer, he yanked up Sam's sleeves, tearing off the bandana tied at the crook of his elbow, checking for any new track marks. He tugged at Sam's skin with his thumb, the probe dislodging the thin, crusted dab of blood from where the needle had punctured Sam's skin earlier, loosening a small bead of scarlet.

"I didn't take any," Sam insisted, his desperation bordering on hysteria. Still, he didn't struggle in the slightest as Dean roughly checked the other arm. "I don't have a syringe. They're in the car—you can check; they're all there. I swear. I swear, Dean. I didn't take it."

Dean paused, his grip still tight. He could feel Sam's heart hammering through his chest, quick and wild, his breathing fast and shallow. His face, his words, his body didn't signal a lie—it just signaled fearful desperation.

Finally, Dean released his hold, stepping back immediately.

Sam slumped slightly from the sudden lack of suspension, his breaths slowing and head dropping.

Even while unease and a thread of guilt needled Dean's skin, the anger still boiled in his gut. He flung his arms out to the side, "The hell happened here, then?"

He recognized one of the bodies—the headless one—as the vampire whom Sam had shoved off the loft, but the other three must be demons. Sam had only been outside a couple minutes. He jabbed a finger toward his brother, his muscles taut with tension, "Cas has been struggling to find demons for the past week, and now, the second you're alone, three suddenly just show up?"

"Crowley's had them watching us," Sam rubbed his throat, his voice still wary, gaze still furtive.

"And they just came out to say hi?" Dean's voice dripped with sarcastic disbelief. If they were here to merely keep an eye on the Winchesters, why suddenly show themselves when Sam was alone? It didn't make sense.

Sam's head dropped, face twisting.

"What, Sam?" Dean demanded, his irritation flaring at Sam's sudden hesitation. Why would they suddenly reveal themselves? Not to kill him, surely. From what Cas said, Crowley had even wanted Dean cured of his demonhood. Trying to kill Sam now would make no sense, especially not while Dean still had the Mark. Even if he died and rose again as a demon, Dean would hunt Sam's killer to the furthest reaches of hell, and he'd ensure their torture would be unending. Crowley wasn't an idiot—he wouldn't risk that. So why? He searched Sam's face, dread icing his veins, "Did they know about the blood?" Were they trying to taunt him, to tempt him?

"No," Sam shook his head without pause, "No, they didn't know."

"So what then?" When Sam didn't immediately reply, Dean cursed. He knew something. He was holding back. "Sam—why'd they show themselves?"

Sam bit the inside of his lip, "I told them to come out—" Dean scowled at that, but Sam continued, "—because I… I knew they were there… I could… sense them… I dunno."

Dean blinked incredulously, "You could what?"

"I don't know, Dean, I just… I think…" Sam shifted in visible discomfort, rubbing his arms anxiously, "It's like I could smell them there, almost."

"You could smell the demons?" Dean scowled, concern and unease pulling at his chest, intertwining with the lingering fury. "What, like sulfur?"

"No, I mean… I don't know, okay?" He looked at Dean helplessly, "I just—I knew they were there. I could feel it, sense it, whatever, I dunno, I just knew."

Dean stared at his brother. "How long?" Sam's brow furrowed in confusion, so Dean clarified, voice terse, "How long did you know? Did you know when we were going in? Did you smell them then?"

"I didn't know, Dean." Sam shook his head, tone insistent, eyes meeting Dean's, "I didn't know until I chased that vampire outside."

Dean paced a few steps, gazing at his brother disbelievingly, "So—you stepped outside, you knew there were demons, and you didn't think you should let me know?"

Sam retreated a step, voice thin, "Dean…"

"Why didn't you call for me?" Dean pressed, wrath biting at his words, "I was right inside—all you had to do was yell."

"I don't know." Another step back; Sam shook his head, gaze downward as if he might find the answer painted in the sea of crimson.

That wasn't good enough. He could've called out to Dean at any point—so why didn't he? "What were you gonna do?" Dean's voice was thick with ire and doubt, "If I had been a few minutes longer in there." Sam didn't reply, didn't meet Dean's gaze, prompting him to level the question, the words fatally steady, "Would you have done it?"

If Dean hadn't stepped outside when he did… how close had he been to losing his brother to another relapse? As he stared at his brother, he found every cell of his body praying that Sam would tell him no. That Sam would offer some reason why he hadn't called Dean. That he'd promise he didn't even think about drinking it—that he'd vow he didn't want to. Dean would give almost anything to hear that, and to believe it to be true.

Sam's voice was a hoarse whisper, his glassy eyes meeting Dean's as he admitted with a feeble raise of his shoulders, "I don't know."

The words didn't land as a surprise. No matter how much Dean wanted Sam to be better already… he couldn't afford to place much stake in hope. Even if he didn't think Sam was lying, Dean couldn't help but think that if he'd lingered inside a couple minutes longer… he wouldn't be asking Sam what he might've done.

He breathed a heavy sigh, the exhale dragging the strength of his rage with it. He glanced back up at Sam, searching his face and finally seeing the terror in the shadows of his eyes, finally hearing it in the echoing quiver of his words. Sam wasn't unnerved by his brother's fury, Dean knew—they'd been around the block far too many times for that. No, it was because he was just as worried as Dean, and for the same reason. Sam honestly didn't know the answer. And that seemed to tear at him in deep, violent gouges.

Dean took a few steps back, wiping a hand over his mouth. He glanced back up after a few seconds, knowing he should've asked earlier, guilt twinging at his heart for not. "Are you okay, Sam?"

Sam's gaze flicked upward. He hesitated, then cleared his throat, though his voice was still shaky, "Yeah, I uh… I'm fine. Vamp got me in the leg." He raised his pant leg to reveal a shallow, rough crimson circle on his calf, then twisted his arm to get a better view of the gash across his bicep, "Demon winged me, too." He raised his chin slightly in gesture towards Dean's arm, "How's your shoulder?"

Dean glanced at the bloody wound through the holes torn in his stained flannel. It stung, but he'd had more important things on his mind. "Fine." His eyes slid back to Sam's. It wasn't what he'd meant by the question, but Sam's avoidance was answer enough.

The older Winchester noticed Sam's gaze lingering on the bodies, and he asked quietly, "What else did they say?"

Sam shook his head, "Not much. Just that they've been watching us since you got back to the Bunker." Sam scoffed, adding, "And that we should be thanking Crowley for all he's done for us."

Dean glanced up at the bitter tone, but he didn't comment on it. "And you're sure they didn't know about the blood?"

"They would've said something about it, if they did." Sam dismissed, eyes still trailing over the corpses, "I killed them, though, just in case."

Dean followed his gaze to the body of a young man, his sightless eyes staring into the veil, the blood forming a macabre halo beneath his head. Dean looked back toward Sam, trying to restrain the accusation from the question, "Did you use your powers?"

Sam's face twitched, but he shook his head, raising the demon-killing knife in answer. "Just this."

Dean nodded, "Good." A glance over the bodies seemed to affirm Sam's assertion, each bearing a gaping, fatal wound. Even if they had to abide the regular dose of demon blood, there was no reason Sam needed to darken his soul further with the use of the unholy 'gifts.'

He realized Sam's gaze still hadn't shifted from the crimson lakes that coated the ground, his face and voice growing more distant by the second. Maybe he didn't drink it before, but… his posture, now… Dean clenched his jaw. He should probably get Sam out of here.

"Sammy… hey—Sammy!" Dean clapped his hands once to finally earn Sam's attention, "It's time to go."

Sam frowned, eyes narrowing, "We can't leave the bodies like this."

"I'll be back to deal with them in a bit, just… you can't be here, man." Dean tried to lighten his voice, but it retained its firm edge, ensnared in concern. It was getting dark fast; he'd be back just as soon as he holed Sam up someplace safe. Not that he was exactly sure how he planned on ensuring Sam's safety while leaving him alone. He'd think of something, just… anywhere had to be better than standing in a sea of demon blood.

"If someone passes by…" Sam's gaze had trailed back to the corpses, even as his sentence drifted off.

Dean gritted his teeth. It wasn't a busy street, but Sam wasn't wrong. "We'll… drag them inside, then. We can deal with the rest later."

Remarkably, Sam only nodded, carefully picking his way through the gore toward the decapitated vampire, before grabbing its arms and dragging it toward the door. Dean joined him, taking a demon by the wrists and pulling it inside. His eyes remained locked on Sam as his little brother slowly tugged the last fallen demon into the building, but Sam didn't stumble.

"Come on," Dean yanked the metal door closed as much as it would give, then wiped the handle with his sleeve just in case. "Let's get out of here."

Sam started silently toward the passenger side of the Impala, his motions almost stiff, dazed. Dean slid into the driver's seat, tossing his machete into the back, before he realized Sam still clutched the demon-killing knife so tightly it trembled. Gingerly, he reached for the hilt, easing it from Sam's grip and wiping it roughly clean with the bandana Sam had been using as a makeshift bandage. Stuffing the bandana in his pocket—he'd burn it later, when he was dealing with the bodies—he set the knife on the backseat beside the bloodstained machete. He'd have to clean the car at some point, and the blades' tips might poke the seats, but he preferred that to monitoring Sam's death grip on a blade slick with demon blood.

The Impala rumbled to a start, and he guided her onto the street, casting a thousandth glance over Sam. Maybe he'd been too hard on him. He could've called for Dean, but otherwise… it wasn't his fault. If anything, the demons were probably there to keep an eye on Dean, given Crowley's invested interest in monitoring the newly cured Winchester who still bore the Mark of Cain. His hands clenched tight around the steering wheel. Yet again, his decisions had landed his brother in a wretched situation. And yet, somehow… Sam had managed to pull through. Surrounded by demons, their blood a feast at his fingertips, and he apparently hadn't even tasted a drop. Maybe it was further proof that Sam's detoxification plan was working after all. And instead of a pat on the back, Dean had shoved him against the car, spat in his face. It was something their father would've done. Nausea churned his gut.

"Sammy, I'm sorry…" Dean started slowly, quietly, "It was just… you know what it looked like."

Sam breathed a low, tired, self-deprecating scoff, "I can't blame you."

Dean glanced at him, "You did good, man." Sam didn't seem to hear him, given his lack of a reaction. Guilt gnawed at Dean's chest. Sam was dealing with enough as it was. He offered a faint, halfhearted smile, adding, "Thank you, for not drinking it. And for using the knife."

Sam merely shook his head and turned his gaze to the window; Dean's words seemed to make as much a difference as raindrops in the ocean.

The encounter had probably just shaken him up something awful. Dean couldn't know just how close Sam had been to another relapse. Sam probably couldn't know, either. He'd be fine, though. In another week and a half, he'd be off the blood. It couldn't come soon enough.

Dean checked the clock—as though that might explain Sam's withdrawal—but Sam still had over a dozen hours until his next dose. He already looked so drained.

Eventually, Dean broached the question, his voice low, "You wanna talk about it?"

Sam again shook his head, rubbing a hand over his forehead, "No."

Irritation danced across Dean's skin at that—he hated it when Sam went quiet like this, despite clearly having something brewing in his head. It was like watching a storm coalesce in the distance. But if he didn't want to talk… he'd earned the space; Dean would let him be, for now. He'd be fine.

Dean eased his foot further onto the pedal, eyes flicking about the signs as he tried to navigate to a more populated part of town. They'd find a motel—he'd drop Sam off, lay low until the night had settled in, think of some way to ensure Sam stayed put. His stomach soured at his first thought—he could lock Sam down, physically, he supposed, but he didn't want to even voice the idea. Sorry, Sam, you did good, but neither of us know how long that'll last, so I need to handcuff you to the bathroom sink again.

He shoved aside the thought. It'd be a last resort. If Castiel could still fly, he could keep an eye on Sam, but he was hundreds of miles away at the Bunker. By the time he got here, the bodies would have already been burned or buried. Maybe… maybe Dean could stay on a video call with Sam, instead. Like a baby monitor, of sorts—though he probably shouldn't phrase it that way to his brother. It wouldn't physically prevent Sam from fleeing in pursuit of a hit, but… at least Dean would know, instantly—he'd drop everything and come right back. It wasn't perfect, but it sounded better than handcuffing his little brother on the bathroom floor. Maybe he'd ask Sam—see what he wanted.

He glanced over at him, but Sam was still brooding at the glass. Dean turned his attention back to the road—he'd deal with that when they found a place to crash.

It took about sixteen minutes to spot a suitable motel. Dean hastily stripped off his flannel and wiped down his face until he looked merely disheveled and no longer like he'd stumbled in from war. After a word to Sam, he stepped into the office and secured them a room for the night—the one on the motel's furthest edge—and pulled the car around.

Sam snagged their duffels from the trunk—they weren't staying long, but they both needed a change of clothes—as Dean unlocked the door and quickly scanned the room. Standard set up—two beds, a television, and a small, rickety table. No demons waiting behind the shower curtain. No hex bags in the bathroom cabinet or in the pillowcases. No shtriga lurking under the bed.

Sam dumped Dean's bag onto the bed nearest the door, and the older Winchester glanced at the time, then at the twilit sky. He still had a few more hours before he could deal with the bodies—until most of the town was asleep. Maybe Sam could tag along and help after all. Dean could certainly use the extra hands—they had plenty of bodies to lug. He didn't know how demon blood worked—once the demon was dead, did its contamination linger in the meatsuit's blood? He wasn't sure, but given the way Sam had eyed it… maybe it wasn't worth the risk.

Dean unzipped his bag, digging out a fresh set of clothes. He might've mopped up his appearance, but he still felt filthy with the blood and grime; his muscles still coiled with the tension he couldn't shake; the Mark still itched at the back of his mind, taunting him with blessed promises of peace. He couldn't just sit—he needed to do something.

He glanced toward Sam, who was slowly, quietly unzipping his duffel. "You gonna be okay if I take a quick shower?" He'd need another before the night was done, but he wanted the ick of blood off his skin, and he needed to clear his head.

Sam nodded, and Dean paused to read his expression, his posture. Finding no clear evidence to the contrary, and no sign Sam would try to make a break for it in the next ten minutes, Dean double-checked that the door was locked, and stalked into the bathroom. He left the door cracked, leaving only a sliver of light to escape, so he might hear the motel room door unlock and swing open, if necessary.

His eyes flicked up to the mirror as he set his keys on the countertop, beside his phone. He was slower to withdraw the flask, tucking it carefully beneath his wad of discarded clothing. A part of him mused that he'd have to remember that he'd stored it there, but that would hardly be a problem. It was impossible to forget about; it weighed heavily in his pocket, as though hell was reaching up to reclaim the souls from the demons from which the blood had sprung. Even aside from its eerie presence, Dean checked for its weight compulsively. He couldn't forget about the accursed thing even when he wanted to.

He twisted the dial and the showerhead sputtered to life. After several seconds, a brief check revealed functional hot water; Dean muttered his gratitude to the empty air.

As he drew the shower curtain, he heard the television flick to life in the room, the audio too soft to distinguish. Dean waited several seconds, listening keenly. But all he heard was the bed creak, and then nothing but the hum of the television and the patter of the shower. Probably wasn't a bad thing, for Sam to distract himself. Heaven knew the kid needed it.

Dean breathed a heavy sigh, turning the dial further to heighten the heat. It stung the raw layer of tissue exposed in the vampire bite to his shoulder, but he should probably clean that out anyway. The water, the heat… it felt good. He closed his eyes and leaned into the flow that stripped the blood and grime from his flesh and sent it spiraling down the drain.

Sam had resisted drinking the blood. He'd had clear opportunity, and he didn't take it. Dean couldn't help the small, faint curl of his lips. His brother wasn't clean yet, and Dean still wouldn't trust him around the blood, but… Sam was gonna be okay. And, not soon enough, they could finally leave this nightmare behind them.