Warning for language, implied physical and sexual violence. This was written before "Hell's Angel."

Bible verses are from the King James Bible, with some slight modifications.

That Old Serpent

Now the serpent was more subtle than any beast of the field which the Lord God had made.

Genesis 3:1

Sam stares down into the sundrenched pool before him, watching a school of tiny silvery fish dart through the water, making little bright flashes of light. With the wind blowing salty spray into his face, he follows the fishes' path, crawling over the rocks to the next pool, and this time he sees a bright red starburst resting on the bottom.

"Dean, look!" He calls over his shoulder to where Dean is kicking up sand on the beach. "It's a starfish!"

Dean hops nimbly across the rocks over to Sam, peering down into the pool. "Uh-oh," he says. "That's not a starfish."

Sam blinks up at Dean, squinting against the bright sun. "Yeah, it is, Dean."

"Nope," Dean shakes his head. "You better watch it, Sammy. That looks like a baby kraken to me."

Sam snorts. "You're so full of shit, Dean."

"Hey, language, shortstack."

"Oh, sorry. You're so fucking full of shit, Dean."

Dean starts to scold him again, but he can't do it without laughing so he stops. Sam reaches down into the pool, sending ripples through his shimmering reflection. The water is nice and warm on the top but biting cold underneath. He carefully strokes his fingers across the starfish. It's bumpy and coarse, not slimy like he thought it would be, and it doesn't seem to mind being touched much.

"Dude, gross. Don't touch it."

"It's okay, it—"

Sam breaks off with a gasp, jerking back his hand and splattering the rocks with icy droplets. A long twisty black creature has emerged from the rocks and is gliding over the surface of the water. He tips backward off his heels, and he can't explain why he's so frightened by the thing's gleaming black eyes.

"What?" He feels Dean step closer to him, feels the warmth of his brother's presence, but it doesn't make him feel safe like it usually does. It makes him even more scared, knowing Dean is in danger, too, that Sam's pulled him closer to it. "Relax, Sammy, it's just a snake."

Dean leans over the pool, his amulet dangling in front of Sam's face, and Sam wants to tell him to get back, to run and save himself, but he can't get the words out and Dean is grinning like nothing's the matter and—

The snake rears up and punches forward, burying its fangs in Dean's neck.

Sam jerks awake, blinking the sleep out of his eyes, and sees Lucifer standing at the foot of his bed, grinning down at him with Cas's face.

He surges upward in his bed, really awake this time, a shout bursting from his lips and a jolt of pain running through his stomach. Just a dream, he tells himself. Except when Lucifer is involved, it being a dream doesn't mean it isn't real.

Heavy, stomping footsteps approach Sam's room. "Sam?!" Dean pounds on the door a few times before bursting in. He bounds over to the side of Sam's bed and starts pawing at Sam's shirt. "What? Did you tear your stiches or something?"

Sam slaps Dean's hands away. "No, no, man. I just…" he swallows down the lump in his throat and nods. "I just had a nightmare, that's all."

Lying to Dean about this stuff never ends well. Sam knows this, and he almost tells Dean about seeing Lucifer. Until he registers that Dean is in his jeans, with his boots still on, and he realizes that it's the middle of the night and Dean hasn't even tried to get any sleep. He looks gray and drawn, and Sam knows how hard these last few days have been on Dean, how freaked out he was about Sam's injury and near death, how he was neglecting to take care of himself in favor of taking care of Sam.

"A nightmare," Dean repeats, blinking. "You screamed, Sammy. A nightmare about wh—"

"Hey," Sam blurts out, cutting Dean off before he can finish the question. "Do you remember that case back in '92 or '93, the haunted lighthouse thing? It was killing kids, so Dad had us hang out at the tidal pools while he worked the job?"

"Yeah, I guess," Dean says, his brow furrowing. "Sammy, what—"

"You got bitten by a snake, remember?" Sam blows on, fighting back a flinch as the image of the thing arcing through the air, of Dean going white and clutching his wounded neck, flashed through his brain. "It really freaked me out."

"Oh, yeah, I remember that." Dean, a hint of a smirk creeping over his face. "You were bawlin' all the way to the emergency room. And it wasn't even a poisonous snake. The docs sent me away with some aspirin and a Band-Aid."

Sam nods. "I didn't like snakes. Still don't. That's what the nightmare was about."

"Uh huh." Dean still looks uneasy. "Well, do you need anything? More meds or something?"

"No," Sam lies. "No, I'm good."

The next day, Sam is lugging a stack of thick ledgers from the library to his room when he realizes that his gunshot wound doesn't hurt at all. Not even a twinge or a dull ache. Confused and a little freaked out, and he puts the ledgers on the table and runs his hand over his stomach. There are no stitches, not even a scar.

"What the hell…?"

"Hiya, Sammy. How's it going?"

Sam's head snaps up. Lucifer is standing in the library, not ten feet away from him, wearing Castiel's skin. Pure panic shoots through his bones before he realizes he's dreaming. "Get out of my head, you son of a bitch."

Lucifer fakes looking wounded. "What kind of welcome is that?" He snags a chair and plops down, swinging his legs up on the table. "You know, you should really be thanking me, Sammy."

A bitter laugh tears up Sam's throat. "Thanking you? For what?"

"For bringing you back after that little mutt smothered you. Pretty undignified way to go, by the way. You really have gone downhill since I left you, kiddo."

"What?" Sam shakes his head disbelievingly. "I didn't die. I just went into shock and my heart rate slowed down."

Lucifer rolls his eyes. "Really, Sammy? Of course that's what the doctors told you. What did you expect them to say? No, you died and I brought you back. You're welcome."

"You expect me to believe that?" Sam spits. "Last time I saw you, you tried to kill me."

"Okay, okay, you're right. I did." Lucifer lifts his legs off the table, leaning forward. "I admit it. I have some anger management issues. I'm working through them. But when I felt that you were gone, really gone, I realized that I wanted you alive."

"Felt?" Sam repeats. His voice quivers, just a little.

"Of course. There's a connection between me and you, Sammy. I can feel what's happening to you."

Sam feels light-headed. "Why would you want me alive?"

"What can I say, Sammy?" Lucifer stands up, his chair screeching across the floor, and Sam flinches. The fact that Lucifer looks like Cas just makes it so much worse. "I guess…" He starts strolling lazily around the table toward Sam, who tries not to but backs away anyway. "I guess I just realized that I would miss you, Sammy. I mean, you always used to plead so nicely. I realized I needed that in my life."

Sam's back hits a bookshelf, and Lucifer keeps coming. Nausea wracks his body, and he tries to shut down the part of his brain so he doesn't remember the Cage, doesn't remember that predatory smile, but he can't.

"And then there's the little matter of this." Lucifer grabs the collar of Cas's crisp white shirt and pulls it down. There's a large dark red spot marring his collar bone, a disgusting patch of damaged and peeling skin. "I may have miscalculated how long this body will hold me." He shrugs. "Oops. Turns out I may need a back-up plan."

Lucifer wants him as a vessel. Lucifer's out in the world and wants him as a vessel. "No. Never. No."

Lucifer smiles. "We'll see about that."

"No," Sam repeats. "That's never going to happen."

"We've been through this before, Sammy. And how did that end?"

"No, never again." Lucifer just keeps smiling at him, gentle and amused, like he's a child throwing a tantrum. "NO!"

"Sammy!"

Sam's eyes fly open and he's looking into Dean's panic-stricken face. The red of the burst vessels in the whites of his eyes contrasts sharply with the green of the irises. Dean's hands are gripping his shoulder, tight enough to hurt.

"What the hell, Sam?"

Sam stares up at him, taking in the lines in Dean's forehead, the unnatural pallor of his skin. "I had a nightmare," he says after a few seconds.

"No shit, Sam. I heard you screaming from the kitchen."

"I didn't mean to bother you. I'm sorry."

Dean blinks, his bloodshot eyes softening. He eases himself down onto the corner of Sam's bed, slowly enough to avoid rocking the bed with his weight, the way he does when he thinks Sam is falling apart.

"Tell me what's going on, Sammy," Dean says quietly. "Is this about the werewolf thing?"

Sam pulls himself up into a sitting position, sighing, knowing that this would double Dean's stress and hating himself for it. "It's not…Listen, don't freak out, it's just…"

Sam tells him, and Dean freaks out.

Thanks for reading! I'll post the next chapter in a few days, if people are interested.