Title: Catalyst

Author: Wincesteriffic Kaz

Info: A witch lays a curse into Sam's skin that could change things forever. Dean/Sam

Author's Note: This started as a PWP one shot inspired by a piece of fan art for my Pimp Momma Fly and has evolved into something requiring a longer story. Lol The boys told me one chapter wasn't enough. Wincest. m/m D/s

Graphic depictions within.

Credit for the FanArt goes to Smut_Slut on LiveJournal and a thank you to Nola for pointing it out for me. :D

Disclaimer: I don't own 'em but if I did…they'd never get dressed. Heh heh heh

~Reviews are Love~


Chapter 1

Dean ran. Splitting up with his brother had been a bad idea. He'd said it then and done it anyway and he wasn't sure he'd forgive himself if he didn't find Sam alive and in one damn piece. He dodged around a dense copse of trees, blinking as he ran through a shaft of sunlight.

"SAM!" Dean shouted it and swallowed when there was no answer. Sam had found this hunt, and, while ganking a witch was always high on Dean's list of worthwhile things to do, this bitch had been anything but easy to find and the trail of her victims just kept growing - men found dead in this forest, faces contorted in screams of agony, naked, and covered in tattoos their loved ones swore they hadn't had. Sam had been positive the tattoos had been some sort of transmutation spell but into what? "Sam, dammit!" A pack of some sort of oversized, spotted wildcats had come after them. They'd reminded him of leopards, were vicious, and Dean had lost Sam in the running fight, unable to actually kill the cats with standard ammo.

"Sam! Answer me!" Dean's level of fear grew with every moment, and he slid to a stop as a sound finally came through the trees. "Sam?" He lurched back into motion and followed the sound, his brother's voice in a low moan of what sounded like pain. Dean broke through the trees and got his first view of his brother. Sam was laid out in a small clearing face down, naked and covered in tattoos. "No. No, no, no. Sammy?" He fell to his knees beside him and rolled Sam into his lap. "Sam." He ran his fingers over the intricate swirls of black lines running up the right side of Sam's ribs and around his back. There were more on his hip and Dean touched those too, fingers gliding over Sam's skin as he frowned and, for a moment, didn't give a damn that Sam was naked in his arms.

"Wake up, buddy. Come on." Dean smoothed his hand up the ink running up Sam's arm to his shoulder. "What'd that bitch do to you, little brother?"

"He's your brother?"

Dean jerked in surprise at the voice and looked up to find the witch standing ten feet away at the edge of the trees. She was tall with black hair curling around her shoulders with a trim body hugged by a narrow black dress and bare feet. She started laughing as he watched and eased Sam gently to the ground. He stood and aimed his gun at her. "What'd you do to him?"

"You're brothers." She laughed harder, so hard she crossed her arms over her stomach and finally wiped tears from her eyes. "Oh…oh, that is…that is absolutely fabulous."

Dean cocked his head to the side and fired; his patience spent. He snarled when the bullet stopped an inch from her face and fell. "What the hell?"

The witch raised her arms and a flash of light illuminated a wide circle that ran the width of the clearing and she stood just outside of it. "Circle of protection and…other things." She smirked and paced along the edge, watching him. "You can't leave until he changes or the curse is broken." She pointed to Sam and smiled. "The curse is etched into his skin…into his soul." She lowered her arm and met Dean's rage-filled gaze. "It has always been me in the circle before and I give them a choice; change or break the curse." She glanced behind her as several of the large cats eased out of the trees behind her and away again. "I'm always a little insulted when they choose to change."

"Break it then!" Dean shouted and put his gun up because there was obviously no point in having it out. "Break the damn curse."

She chuckled and moved back into the trees. "There's only one way and seeing as you're his brother…" The witch began laughing again as she melted back into the trees out of sight. "…I don't think you'll be willing to do what's needed. I would have enjoyed it immensely. He's very beautiful." Her voice floated out of the forest. "I think your brother's going to be joining my pets very soon. Enjoy!"

"You bitch!" Dean shouted it into the trees as her laughter trailed off into silence. "Son of a bitch!" He went back to Sam and knelt, pulling his brother back into his lap. "Ok, Sammy. We can figure this out." Dean let what the witch had said sift through his mind and got a distinctly uncomfortable feeling for no reason he could name. Sam stirred in his lap. "Sam?"

Sam moaned softly and blinked, opening his eyes and found Dean looking down at him. "Dean?" He hissed in a breath in pain and looked down at himself, eyes widening in surprise. "Wh…why am I naked and…" Sam brushed a hand over the tattoos running over his skin. "…what the hell?"

"Bewitched Bitch got her claws in you, dude." Dean scowled and looked out into the forest. "You're uh…you're gonna turn into one of those cats unless we break…this." He touched the ink on Sam's chest.

"Ok, how do we break it?" Sam moved to sit up and fell back into his brother's lap with a soft gasp as pain shot through him. "Shit."

"Easy." Dean helped him sit and studiously kept his eyes north of his brother's crotch.

"Dean, seriously. How do we…how do we stop this?" Sam felt incredibly vulnerable sitting there without a stitch of clothing in a forest clearing and his big brother rising to stand over him. "Did she say?"

"Yeah, Sam 'cause all the bad guys monologue and give away the evil master plan. No, she didn't say." Dean rolled his eyes and paced to the edge of the circle. "Not exactly anyway." He glanced around at Sam's bare, ink covered back and then shook his head, dismissing the idea that was starting to form.

Sam frowned and hunched over himself. He could feel…something…beginning to happen. It was an odd feeling as if some foreign thing were starting to…stretch deep inside him and he gasped. "Dean?" He grimaced and wrapped his arms around himself. "God…Dean?" Pain started to creep out along his arms and legs and into his head.

"Sammy?" Dean spun and was back at his side in three long strides. He put a hand on his brother's trembling shoulder. "What's going on?"

Sam gasped again and heaved out a breath as the pain eased with Dean's hand on his shoulder. "It's…it's backing off…some. Shit."

"What is it?" Dean knelt and tried to get a look at his brother's face.

Sam shook his head. "I dunno…pain. It's better now."

"Ok." Dean took a breath and squeezed his shoulder. "Gonna see if I can get us outta this circle." He stood and went back to the softly glowing ring. Pressing his hand against it was like pushing at a brick wall; it wasn't going anywhere. He tried to scuff over it with his boot and met the same resistance. "Now I know how demons feel," he said ruefully.

Sam grunted softly as the pain returned and twisted in his gut. He tried to breathe past it, but it grew and he collapsed to his back with an agonized cry. "Dean!"

"Shit!" Dean ran back to his brother where he writhed on the grass and dropped, taking his shoulders. "Hey, hey. Talk to me! Breathe, Sam!" He pulled Sam up against him as his cry trailed off into gasping breaths and held him while Sam's fingers curled into his shirt. "Take it easy."

Sam shamelessly burrowed his head into Dean's chest, needing the comfort as the burning agony eased off again with his touch, and his pain-fogged brain made the connection. "S'you."

"What?" Dean looked down and tried to push him back but Sam held on.

"You…you move away and it gets worse." Sam shook his head. "Don't get it. I don't…why?"

Dean's brain finally made him really hear what the witch had said and he went cold, trying for denial and failing with the clear evidence that his touch was helping his brother. "Ok. This is not…we gotta find another way." He was suddenly all too aware that he was holding his very naked little brother. "Lemme go, Sam. I gotta figure this out. Come on."

Sam struggled against the urge to pull Dean closer and uncurled his fingers, leaning away. He nodded. "Alright. Just…hurry." He sat back on his own as Dean shot to his feet and walked away. "You know something," Sam said as the pain bloomed inside him again and he curled over himself, slamming his eyes shut with the strength of it. "Wha…what…aren't you telling me?" He knew the air was chilled with autumn, but his skin felt flushed with heat, burning to match what was happening inside him as he felt that other 'presence' begin to stretch again, as though it were waking up.

Dean turned when he heard the strangled cry escape his brother and stood for a moment, watching as Sam fell over and curled around himself in a tight ball. Sam whimpered and Dean's heart broke a little. He scrubbed a hand over his face and hoped, maybe, it wouldn't have to go as far as he thought it was going to, to save Sam. "Ok, buddy. Easy." Dean went back and dropped to the ground next to Sam and after a moment's hesitation, took his shoulders and pulled Sam up against him again. Sam sobbed out a breath and collapsed against him and Dean groaned. He moved Sam away just enough to shrug off his jacket and pull his shirts over his head and toss them aside.

"Dean, what…" Sam took in a shaky breath of relief as his brother pulled him against his bare chest and that shifting thing inside him subsided. "Fuck."

"Here's the thing, Sam. The witch, she, uh…" Dean looked up and shook his head. "…she may have intimated that there's a way to save you that she'd enjoy a lot more than I would."

"What the hell does that even mean?" Sam snaked an arm around Dean's waist without thinking and clung to him, pressing his face into his chest to hear his heart beating.

Dean swallowed, cleared his throat, swallowed again, and had to make himself say it. "You gotta have sex to break the curse." That was what the witch had meant about her enjoying it. He knew it with certainty. He knew he was blushing furiously when Sam reared up and away to look at him in shock.

"What?" Sam exclaimed and started to shake his head as Dean looked everywhere but at him. "Uh…ok. So, we just…we go…back to town and I find a willing…"

"No." Dean shook his own head and met the rising fear in Sam's. "I can't break this damn circle, dude. The witch said it falls when you break the curse or you…you change." He looked at his little brother, the kid he'd raised, and knew he wasn't going to let that happen no matter what he had to do to save him. It gave him a measure of calm as Sam suddenly gasped and folded back into him with a muffled cry. "Sam?"

The pain blew through him again, even with Dean's touch, and Sam began to understand that the thing inside him trying to get out wasn't going to be placated with Dean just holding him for long. He shuddered against his brother. "No. No. Dean…" A fresh wave of pain arched his back, and Sam went to the ground with a cry.

Dean scrambled to him and pressed Sam's shoulders into the grass while he writhed, his face a mask of agony. "Sammy…" Dean broke off when he felt his brother's shoulder move under his hand, the bone inside shifting with a little pop and Sam screamed. "Holy crap."

"Make…make it stop!" Sam yelled and gasped. "Don't let it…don't let it out!"

Dean held him down and saw his fingers curl into claws, felt and heard Sam's joints popping and a sick feeling moved through him when he realized Sam was bleeding from his fingertips, his toes, his ears… "Fuck!" Dean steeled himself and rolled on top of his brother. He used his body to pin him, pressing their chests together and he tried not to feel Sam's ribs popping and crushed his mouth to his brother's.

Sam's voice gave out mid-scream as Dean's mouth pressed into his, and even the thing inside him seemed to pause. Sam could almost see it, like a big pacing cat inside him, and it cocked its head curiously as Dean's tongue shoved between his lips. Sam groaned and didn't fight it, giving himself over to the feel of Dean's soft lips and tongue tangling with his own as the pain ebbed slowly back. The cat seemed to come a decision, deciding it would accept this over blood, and a wave of desire overcame him.

Dean felt Sam calm beneath him, the disturbing shifting of bone and muscle stop, and he nearly jumped out of his skin when he realized the vibration coming from his little brother's chest pressed so firmly against his own was a purr. He thought maybe it should freak him out, but, instead, it touched something deep inside him, something he'd crushed and hidden away a long time ago, and he growled into the kiss. He dug his fingers into Sam's hair and held his head, turning it as he deepened the kiss and got an answering growl from Sam.

Sam's hips jerked up into Dean's, and he felt a snarl curl his lips at the feel of the denim between them. The feeling was alien enough to let his own thoughts back in, and he gasped into his brother's mouth, "Dean!"

"Don't fight this, Sammy. Please." Dean leaned back only enough to see Sam's eyes. The look in them bordered on panic with something else, something more feral, lurking in the background. "You'll die, Sam. Not lettin' that happen." He put a grin on his face for his brother. "Besides, all the ladies say I'm pretty fly."

"Oh, my God," Sam groaned, surprised into a laugh. "I can't believe you're quoting Offspring. Really? Now?"

Dean chuckled and leaned in to rest his forehead on his brother's and closed his eyes. He was pretty sure the thing inside Sam wasn't going to give them much longer. "I need to know you're ok with this, Sammy." Dean whispered it against his lips. "I'm not gonna…I don't wanna rape you. You gotta be ok with this."

Sam sucked in a breath as the fear came back. Dean was right. If he refused, if he fought, he'd be forcing his brother to do this TO him to save him and he couldn't; Dean would never forgive himself. Tentatively, Sam slid his hands up Dean's sides, feeling his brother shiver under his touch, and he flattened his hands over the corded muscles of his back. "Ok." Sam felt the cat inside him pacing restlessly and swallowed as that other mind began to rise up again. "It's alright. It's alright, Dean."

Dean sobbed out a breath in relief. He felt Sam's fingers begin to curl against his back and knew their time was up; the thing inside him wanted more. Dean dove back into his brother's mouth as a possessive growl trickled over Sam's lips and there was nothing human in that sound. "No." Dean growled it back and thrust his hips into Sam's, looking into blue-green eyes as a stranger looked back at him for a moment. "He's mine." He said it fiercely, and leaned down to bite into Sam's neck, hard enough to taste the hint of copper on his tongue.

Sam cried out, but this time it was from pleasure, not pain, with the feel of Dean's teeth in his skin and the hard length of his brother's cock rubbing against his own. He growled again at the fabric separating them, and pushed at the waist of his brother's jeans, blunt nails clawing him in his haste to get rid of them.

Dean groaned, feeling Sam's nails as he tried to get his pants off. "Pushy." He smiled and reared up, planting a hand firmly in the center of Sam's chest. "Stay." It was an order to an animal mind he knew wanted to be dominated…needed to be taken.

Sam settled under the hand, only willing to wait because it was clear Dean was taking his pants off. He stayed when his brother took the hand away and stood to strip his jeans and boxers off and a lustful purr rumbled out of his chest at the sight of all the beautiful skin. He wanted to mark it up so Dean would know he was his.

Dean chuckled a little breathlessly as he looked down at his brother. "Damn. Feel a little like I'm lunch all of a sudden."

"Not lunch." Sam whispered as Dean, now finally naked, dropped to his knees. He reared up and sank his own teeth into his brother's chest over his heart, sucking and then licking. "Mate." He growled it into Dean's flesh while a silent litany of 'mine, mine, mine' chanted through both the cat's mind and his own.

"Fuck." Dean's breath stuttered out of him as Sam's tongue and teeth moved over his chest and up to his neck. He was going to be marked to hell before they were done, and, as he watched Sam's dark head moving over him, he decided he liked the idea, but Sam wasn't the one who needed to be in charge here. Dean fisted a hand in the back of Sam's hair and pulled, making his brother gasp and moan wantonly as Dean dragged his head back. He grinned and bent his head, sucking Sam's bottom lip into his mouth and biting until his brother whimpered and his hands scrabbled at Dean's sweat-slick skin for purchase. Dean leaned back and smirked at Sam's kiss and bite swollen lips. "Better."

Sam tried to pull forward, moaning as Dean's fingers tightened in his hair. He wanted more, needed more, and he snarled, another feline growl escaping his lips as Dean pushed him down and took hold of his hip, flipping him over. Sam growled and got to his knees with the cat bristling in his mind. He felt it bunch its muscles, readying an attack, and then Dean's teeth were in the back of his neck. It was like he'd flipped a switch. The cat fell back, momentarily content to be controlled, and the purr vibrated out of Sam once more.

A cat's a cat, Dean figured and had seen enough late night Wild Kingdom broadcasts to know how big cats subdued their mates in the wild. It surprised him when it worked as he sank his teeth into the back of Sam's neck and his brother went pliant under him and the purr rumbled out of him again. He took his mouth away experimentally, seeing the marks of his teeth filling with blood and Sam stayed where he was. Dean blew out a relieved breath and leaned back, letting Sam hang his head as Dean knelt behind him. He looked over his brother's body and pulled his fingers along the tattoo on his back again and around the curve of his ass. Sam pushed back into his touch eagerly. Confusion was screaming in the back of his mind and not a little panic at what he was about to do; this was his little brother. Yet, even as his subconscious told him this was wrong in every way that mattered, he knew he had to do it to save Sam and that…that made it right because there was nothing he wouldn't do…nothing to keep Sam safe.

"Sam. I don't know if you can hear me in there, but, uh…this is gonna hurt." Dean groaned and reached out to tunnel his fingers in the back of his brother's hair. He used the grip to pull Sam up to his knees. He put the fingers of his other hand to Sam's mouth. "Suck them, Sammy," Dean murmured into his ear as he slid his fingers into his brother's mouth, and his cock jumped in response to Sam's eager tongue lapping around his fingers and wetting them with his saliva. "Shit."

Sam pulled his brother's fingers in, sucking and wishing it was Dean's cock instead. He wrapped his tongue around them, loving the shivering moan that Dean let escape in his ear, and he chased after them when Dean pulled them away.

"Easy." Dean put his hand down and pressed his now wet fingers to the tight ring of muscle between the cheeks of Sam's ass. While he'd never done this particular act with a guy before, he had done it with a few adventurous women and understood what he needed to do. He put his teeth to the back of Sam's neck again. His brother growled, Sam's head dropping forward to give him better access, and Dean felt his muscles release and his fingers slid in. "Holy crap."

A loud moan broke out of Sam, and he pushed his hips back into his brother's touch, trying to force more of his fingers inside him. He was becoming desperate as the cat inside him grew impatient waiting to be taken.

Dean gasped and removed his fingers and leaned back. "Ok, I get it. You're ready." He spit into his own hand several times, wishing they had even a bottle of damn lotion, and smoothed the moisture onto his own cock, trembling with the touch. Sam bucked back into him and turned his head, trying to get Dean under his teeth again.

"Easy, dammit!" Dean fisted a hand in his brother's hair again and used it to force him down to the ground.

The cat in Sam's mind snarled happily and pushed Sam's ass up in the air, spreading his legs, inviting Dean to get the hell on with it already.

"So fuckin' eager, damn." Dean lined his cock up and took hold of Sam's hips. He was shaking with need himself now, his body responding to the raw, feral, sexuality of it all, despite the bizarre circumstances. The part of his brain that might have cared about the implications of what they were doing seemed to have shut down somewhere along the line. He bent over his brother to bite the back of his neck again and groaned long and loud as he pressed the head of his cock inside his brother and had to close his eyes with the sensation of being held tight inside him. "God, Sammy."

For a moment, Sam and the cat were frozen in pleasure and Sam slammed his eyes shut, but it didn't last. They wanted more, and he braced his hands on the ground and shoved his hips back to take Dean inside him completely. The feeling as Dean's impressive length slid into him inch by grudging inch while Dean bit off groans and cries behind him made Sam's entire body shudder and he shouted at the strength of the feeling of being filled so completely. What pain there was was swallowed in the pleasure, need, and want to have more and harder and now.

Dean shouted in surprised pleasure as Sam took all of him into him at once and was overwhelmed for a moment. "Holy….holy fuck, Sam. God!" He gasped, releasing the back of his brother's neck. Obviously, the cat had no interest in finesse, so Dean gave it what it wanted. He took hold of Sam's hips, leaning back to his knees and pulled out then used his brother's hips to slam back home and surprise a shout from him. Dean set a steady rhythm, slapping solidly against Sam, in and out. Every wanton, needy, desperate mewl, gasp, moan, and cry that passed Sam's lips added fuel to Dean's fire and drove him harder and faster toward the edge, and he shifted slightly to the side and thrust home hard, finding Sam's sweet spot as Sam practically screamed.

"Dean!" His brother's name erupted from his throat as Sam sobbed for breath between cries of overwhelming pleasure.

"Sammy?" Dean said in surprise. It was the first word his brother had spoken, and he leaned back down over him. He reached around and closed his hand around the front of Sam's throat, using it to pull his head up.

"Dean…God!" Sam gasped. "Don't…don't stop. Oh, God. I'm so close!"

Dean dropped his head on a heavy groan. "Fuck, Sammy." He slid his other hand around Sam's hip and took hold of his cock, long and hard and straining in his hand as Dean started to stroke it in time with his thrusts. "Come for me, little brother. Come. Come on." He panted the words in Sam's ear, slamming into him harder and faster, driving Sam's throat forward into his hand with each thrust.

Sam felt his orgasm like something alive and coming for him. It slammed into him with the force of a train and threw his head back on a scream. He felt Dean's hips stutter, heard his brother shout his name in his ear with a guttural cry, and then Dean's cock was filling him. The pleasure burned through him like a wildfire as he came and convulsed with the force of it. It ripped a scream from him that seemed to go on and on until finally he collapsed to the ground with Dean atop him, spent and gasping for air.

Dean went to the ground with his brother, his body shuddering with after-shocks of one of the most intense orgasms he'd ever had in his life. His cock twitched inside his brother, and Dean moaned as it wrung another small orgasm from him. He forced himself to move, pushing up on one elbow to look down and gasped in a breath. The tattoos on Sam's skin were quickly fading and washing away from his skin as though they were being un-drawn.

"Sammy?" Dean asked, his voice hoarse, and shifted his hips, slipping out of him with a hiss of discomfort. He moved and rolled Sam gently onto his back and against his chest. "Sam?" Dean brushed sweat-damp hair from his brother's face, concerned when Sam's eyes stayed closed. "Really need to know you're ok here, buddy. Come on. Sam." He dropped his forehead to his brother's. "Please tell me it's you in there," Dean whispered.

"Still me." Sam whispered it to him, unable to speak any louder. His throat was raw from screaming, so he smiled and turned his head up until he could feel Dean's lips brush his. "M'ok."

"Thank, God." Dean tightened his arms around Sam and looked up again. He jumped slightly as the circle that had kept them in flared suddenly and vanished with a soft pop. "Nice. Circle's gone. We can get out of here."

"Mmm hmmm." Sam hummed it and brushed his lips over his brother's contentedly. He couldn't feel the cat in his mind anymore, and, thanks to Dean, he was spent and sated with pleasure and didn't give a damn if a herd of dinosaurs rode down on them just then. He wasn't moving.

Dean chuckled and gave his brother the kiss he seemed to want. The witch's curse had crashed down every barrier they had, and being embarrassed now seemed like a ridiculous idea. He supposed he could run from this moment, that they both could, but he knew somehow it would make them both miserable. He sighed and raised his head, letting Sam nuzzle his head under his chin. This wasn't their fault, and it certainly wasn't Sam's fault, and he couldn't make himself punish him for this.

"You sure you're alright? Just you in there?" Dean smoothed a hand down his brother's ribs, enjoying the feel of soft skin and no tattoos. "Not gonna have to buy you catnip or anything?"

Sam found enough energy to punch him weakly in the ribs and snorted into his neck. "Shuddup."

Dean chuckled and pulled him closer, looking out into the forest around them. "We still gotta find and kill that bitch," he said softly and curved a hand around the back of Sam's head into his hair. Dean felt the possessiveness he always felt toward his brother, but it seemed somehow...more now than it had before. "We'll get her later when you're on your feet again." He smirked. "And dressed."

"'Kay." Sam wrapped his arm around Dean's waist sleepily, content in the knowledge that Dean had his back. Dean would protect him. Some small voice in the back of his head tried to warn him that the way he was feeling right then wasn't quite normal…not quite right…or human…but Sam wasn't listening as he slipped into sleep with Dean wrapped around him.


To Be Continued…