Disclaimer: I do not own Supernatural.

This is inspired by A Mutually Beneficial Compromise by CaseofUnderjoy (lullabelle) over on AO3.

Be Careful What you Make a Deal With

Sam stumbled into his motel room, he was drunk, and he knew it, but what did it matter? Stupid demon refusing to deal…he closed the door and stumbled and then fell back as a man and woman slammed into him, pinning him against the door. He fumbled for the knife only to have it yanked away.

"Thanks for keeping this warm for me, Sam," she smirked, and Sam frowned, his head pounding from hitting the door and the alcohol.

"Ruby."

"It's nice to be back. Where I was, even for Hell, it was nasty. I guess I really pissed Lilith off. Imagine my relief when she gave me one last chance to take it topside. And all I had to do was find you and kill you." She gently caressed the skin of his throat with the blade without cutting the skin.

"Fine. Go ahead….Do it." At least the pain would stop. To his shock she turned and stabbed the other demon instead.

"Grab your keys. We got to go. Now!" She ordered but Sam was barely staying upright. Seeing that she grumbled but looked around and grabbed his bag before hauling him out of the room and over to the Impala, dumping him in the passenger seat where he promptly passed out. She shook her head and began driving, leaving the town for the highway. She drove for several hours before pulling off into another town and getting a motel room to wake for dear Sammy to wake up. She hadn't expected him to be in this much of a mess, but it had been a few months.

,,,,,,,,,,,,,,

Sam groaned and pressed a hand to his head; how much did he drink last night?

"You know what sounds good? French fries. I'm starving. I just escaped Hell. I deserve a treat. You know, a "thank you" would be nice." A female voice offered, and he sat up, hand going for a weapon.

"Who?" he stared blankly at the woman lounging in a chair….and this wasn't his motel… and then he remembered…Ruby. "Who asked for your help?"

"You have no idea what I've been through. When Lilith gets pissed, she gets creative. You want to hear about the corners of Hell I've seen, Sam?" She demanded as she stalked closer, angry.

"No, I don't." At the moment he just wanted a fist full of pain killers.

"And the things I had to do to convince her I was sorry? That I could be trusted?"

"Well, this'll definitely get you a fat Christmas bonus," he mumbled as he fell back onto the mattress. She must have moved him when he passed out, he vaguely remembered her telling him to move.

"Very funny. I'm a fugitive... For you, Sam. I took all of this risk to get back to you, so, yeah, I deserve a damn "thank you.""

"Who asked you to save me?" Being dead surely hurt less than living, knowing his brother was dead because of him.

"I'm just trying to help," she offered, and he felt the bed dip as she sat beside him.

"Can you help me save Dean?" he asked, slowly turning his head to look at her.

"No. Nothing, I know of is powerful enough to do that." She admitted, and he glared.

"Then I have no use for you."

"What?"

"Get out." He pointed in the general direction of the door.

"Sam…"

"Whose body are you riding, Ruby?" he was so tired, he was always tired these days.

"What do you care? You've never asked me that before." She sounded genuinely confused.

"I'm asking now."

"Some secretary." She shrugged, not like she cared but she'd picked her for her looks.

"Let her go."

"Sam..."

"Or I send you right back to Hell." Hangover or not, he knew a lot of exorcisms without having to even think about the words. He felt the bed move again and then the door shut. He forced himself up to lock it and then put up salt wards before passing out again.

,,,,,,,,,,,,,,,,,,,,,,

Ruby looked at the abandoned house she had tracked Sam down to, hopefully this time he was at least sober. She walked up and knocked, waiting until Sam yanked it open, shotgun in hand. Oh good, he was sober, mostly at least. She held up a piece of paper. "Proof. This body is 100% socially conscious. I recycle. Al Gore would be proud." She grinned and handed it over.

Sam put the shotgun down and took it to read. "You grabbed a coma patient?"

"You didn't want me to take a body with someone in it, and I made sure that the spirit was gone. Apartment was empty. You happy?" She demanded, flipping the long brunette hair, maybe this body was a better idea anyway, hadn't Sammy nearly proposed to a blond before the girl was killed by Azazel, so that was probably not a good thing to remind him of.

"Why are you here?"

"I can't bring Dean back. But I can get you something else that you want," she smirked, moving in ways that showcased the body. It had taken some time to find one that suited her needs and standards.

"And, uh... what's that?" Sam asked, and she hid a grin when she saw him checking her out sneakily.

"Lilith."

"You want me to use my psychic whatever."

"Look, I know that it spooks you –" she started only for him to jump in.

"Skip the speech. I'm ready. Let's go."

Huh, hadn't seen that coming. "Slow down there, cowboy."

"Just tell me what I have to do."

"Look, Lilith is one scary bitch. When I was in the Pit, there was talk. She's cooking up something big - apocalyptic big."

"So, let's kill her."

"You want to go in there and half-ass it like before? We have the time to get it right. Let's get it right." She argued, it wasn't anywhere near time for him to be sent after Lilith yet. She didn't know the exact plan, just that she needed to get Sammy well and truly hooked. It was going to take time, she needed to move slowly, or else risk Sam realising what was happening and breaking free.

"Okay. What do you want from me?"

"Well, a little patience... and sobriety. Promise me that... and I will teach you everything I know."

Sam hesitated, obviously torn, but then he nodded. "Deal."

,,,,,,,,,,,,,,,,,,,,

Sam was trying to exorcise a demon tied to a chair in a devil's trap, but it wasn't working, not that Ruby was surprised. Some black smoke came out of the demon's mouth, but then it went back in and she was shocked he'd gotten that far. Sam held his head in pain, grimacing, a drop of blood dripping from his nos. As the demon began to laugh, Ruby killed him with her knife. "Not funny." She looked at Sam, seeing the disappointment and pain and happy, he was getting desperate enough now. "Just give it time, Sam. It'll get better," she offered gently.

"What? I need more practice?" he slumped down in the empty chair across form the body.

"I'm not talking about pulling demons. I know losing Dean was –"

"Hey! I don't want to talk about it. You know what? Where do you get off slapping me with that greeting-card, time-heals crap? What the hell do you know?" Sam snarled, and she knew it was due to pain.

Ruby walked towards him, hips swaying. "I used to be human. And I still remember what it feels like to lose someone. I'm sorry." She gently put a hand on his shoulder.

"Uhn-huh. Don't. I can't."

"Sam, you're not alone." She pressed closer to him, leaning down to kiss him.

Sam jumped up and moved away. "What are you doing?"

"Sam, it's okay!" maybe it had been too soon?

"No, that is anything but okay!" he denied, shaking his head.

"What's wrong?" she moved closer again and hid a smirk as she saw him swallow, hard. Oh, he was interested alright.

"What's wrong? Where do I start?"

"Is it because of the body? Because I told you - it's all me inside of here. There is no one else. And it's nice inside this body, Sam. Soft and warm." She took his hand and pressed it to her breast, hearing his breathing hitch.

"What are you doing?" he demanded.

"Isn't it 'cause you're really scared to go there with a demon? Because it's wrong and it's bad and we shouldn't?" She pushed, her free hand moving up his chest to wrap behind his neck, tugging him down. "You know you want it," she leant up to meet his lips, kissing him. She felt his other hand moved around her back, holding her close and felt a surge of triumph. She bit her tongue and then deepened the kiss, not letting him pull back when he tasted blood. She felt his hands slip down to her hips, caressing bare skin as her top moved up. She moved flush against him, feeling exactly how interested in what they were doing he was. She heard him groan, fingers digging convulsively into her skin and she looked up to see his skin flushing, sweat beading on his forehead. She broke the kiss and he chased her lips, looking dazed. She pried his hands off her, holding them and pulling him out of the bare room to the bedroom. "I want you Sam." She yanked her top off and smiled as Sam began fumbling with his own clothes.

,,,,,,,,,,,,,,,,,,

As soon as Ruby kissed him, Sam knew she was right. He shifted to hold her close and then she was deepening the kiss. He tasted something….metallic and tried to pull back but she held him to her and he relaxed, the taste fading away as his hands dropped to her hips, giving him bare skin to caress. He felt a flush of heat spread through him, jeans becoming too tight, his fingers digging into her as he groaned. He was hot….skin too tight and then the cool lips were gone, and he tried to get them back. She moved away, and he didn't like that but then she was pulling him along and Sam let her, he felt…fuzzy. He heard a buzz of noise, saw her lips moving but then she was stripping…that was a good idea. He fumbled with his clothes and then he was hitting the mattress and looking up at her as she grinned, dark hair falling around them. His arms went around her waist, trying to pull her down and he sighed as her cool skin came to rest on his overheated body. He kissed her again, not caring for the strange taste this time, lost in his need to quench the fire burning through his veins.

,,,,,,,,,,,,,,,,,

Ruby smiled and then Sam was pulling her into another kiss, once more letting her bleed into him, though her tongue was hurting a little. She shifted her position on top of him, pushing herself down onto him and Sam broke the kiss to gasp, eyes rolling back in his head. "It's alright Sam, I'll take care of you," she whispered in his ear before nibbling his earlobe as she began to move. Her hands moved over his body, caressing too hot skin, as she continued to whisper in his ear. She was very pleased by how well he had reacted to her blood and was looking forward to seeing how quickly it worked on him. How soon would it be before he began showing signs of obeying what she told him during these times. It didn't hurt that this felt really good, surprisingly even better in a body that had only her inside.

,,,,,,,,,,,,,,,,,,,,,

Sam cleaned the shotgun, mind spinning. What the hell was wrong with him? He'd has sex with Ruby….a demon! And not just that once. It was like she kissed him, and he lost the ability to say no, to push her away. Why? Was he that desperate for any kind of comfort? He had to admit, the sex was…incredible, better than any before but it was wrong, wasn't it? At least he was learning, getting better at his powers. He'd finally managed to exorcise a demon with his mind, though not kill it. It was still a step in the right direction.

He didn't notice Ruby watching him with a frown before she cleared her expression and walked over, draping herself over him. "Penny for your thoughts?" she nuzzled at his throat, saw his hands clutch the shotgun.

"Just thinking," he put the shotgun down and she moved to sit in his lap, going to kiss him but he jerked back. "I'm not in the mood Ruby," he denied.

"Come on Sam, I'll take care of you," she purred, shifting so she was straddling him, seeing his reaction to those words. She pressed her hand to the front of his jeans. "This says you're in the mood." She bit her tongue and kissed him, hard. He was tense, hands on her shoulders, trying to push her away so she fumbled with one of his knives and lifted it to cut across her upper chest, making sure to go deep enough to ensure a nice flow of blood. She then dropped the knife and broke the kiss. Sam gasped for air and shook his head, trying to clear it and she pulled him down to the wound, holding his head in place with one hand, the other stroking his hair. She felt Sam swallow and then slowly be began to suck and lap at the wound, truly drinking her blood for the first time. "That's it Sammy, you need this, you crave it. Let me take care of you," she murmured encouraging words as he drank, feeling his body temperature skyrocket even as his hips began to move, seeking friction. She got up and looked down at him, his mouth smeared with blood, skin flushed, eyes glassy. She pulled him to his feet and he stumbled drunkenly, so much for making it to a bed. She pushed him down on the ground and ripped his jeans off before taking her own off and getting on top. "So good Sammy," she praised as he latched back on to the wound without any encouragement. "Isn't it easier to do as I tell you?"

,,,,,,,,,,,,,,,,,,,,,,

Ruby watched Sam, frustrated. Three months in and she was nowhere near where she wanted to be with him. Some stuff had taken easily, and he was now fully addicted to her blood and eager to sleep with her. Deeper alterations to his mindset weren't going as well. She needed something more certain than blood, she was being limited by needing to move slowly so that he didn't realise what was happening and fight back. She needed a way to make him compliant and eager, she'd considered spells, but they all had negatives of some sort, many of them ending in Sam's death before he could fulfil his role in things. That meant looking to a creature. Even there her choices were very limited, she needed Sam obedient but not an idiot. Basically, she wanted his mind intact just lacking that pesky free will.

,,,,,,,,,,,,,,

In the end, Ruby had to call on older powers than even Lilith to get what she wanted. Then she returned to the abandoned house they were squatting in and stripped off before sliding into bed beside the still recovering Sam. She'd made sure to fully wear him out earlier, not wanting him to wonder where she was. She stroked his cheek and he stirred slightly but didn't wake, an arm wrapping around her waist to pull her close and she smiled. She ran her hands over his naked body before nuzzling at his throat, licking the warm skin, sucking on his pulse point as she rolled him onto his back and Sam groaned in his sleep, beginning to wake. She sucked harder as she moved to straddle him and then sank new fangs into the vein, injecting him and she felt Sam wake, hands clutching hard at her body even as he shuddered, hips jerking under her as his body reacted to the substance now flooding his bloodstream, satisfying his craving for her blood while inducing a powerful, drawn out orgasm. She pulled off his throat and looked at his face, seeing his skin flushed, eyes rolled back as he gasped for air.

She watched as he struggled to focus on her, eyes wide in shock, pupils dilated, chest heaving. She smiled and kissed him before rolling off him, to gently stroke his skin as he slowly calmed down.

"What…"

"Feel better?" She asked and he blinked, realising that shaky feeling he'd had the last day was gone.

"Yeah…Ruby?"

"Shh Sammy, I'm helping you get stronger," she promised, and he nodded. It was technically true after all.

,,,,,,,,,,,,,,,,

"Ruby, you bit me," Sam commented, running a finger over the mark on his neck and then swallowing, oh, it was rather sensitive.

"I did."

"That's not a demon power."

"I did this for you Sam," she purred, running her hands over his shirt covered chest. "This will help even more, you don't miss it, do you?" she asked, and Sam hesitated before shaking his head.

No, whatever she'd done, he felt better than he did when he drank her blood. He wasn't even sure when he'd started doing that, it was all messed up with sex, but he'd do what it took to get strong enough. He forced himself to focus and ask about what she'd done to herself.

Ruby just grinned and allowed him to inspect her new dental work, explaining that the fluid she injected him with had multiple uses, depending on the situation and that it was far stronger than her blood. She just didn't tell him everything it could do, he didn't need to know some of it yet and some of it ever.

,,,,,,,,,,,,,,,,,,

Sam was hesitant about her bite, but his mood began to dip after four days, by day five his hands were shaking, and he didn't really argue when she kissed him, letting a little of the fluid trickle from her fangs as she deepened the kiss, feeling him harden beneath her. "Bed," she muttered, and Sam got up, pulling her to the bedroom where they stripped off. As soon as they were on the mattress she struck, not giving him the chance to think about it. Sam cried out, limbs limp as she keeps up a steady stream into his blood, forcing his body to orgasm several times before she got on top of him and took him into her body, getting one last orgasm out of him as he whimpered and writhed weakly before simply passing out.

She lay beside him, gently petting his hair. "You're so perfect Sammy, I love the sight of you lost to pleasure under me. She knew the link between them was growing, she could feel his presence at the back of her mind, getting stronger every time she bit him.

,,,,,,,,,,,,,,,,,,,,,,

She began experimenting with influencing him, making sure to keep a mental eye on his emotions. She started out with simple things, like contentment or sleepiness. It took a few weeks but then one day Sam yawned, eyelids drooping, and he slowly slumped down on the book he'd been researching in and she smiled happily. She got up and stood behind him, running her fingers through his hair as he breathed deep and steady, body totally relaxed. She pulled his chair back from the table and he began slumping forward until she caught him and simply carried him to the bed, stripping him off, still feeding him sleepiness. Then she slowly changed the feeling to arousal and his body slowly began to react until hazel eyes opened to slits and he reached for her. "So good Sammy," she murmured before kissing him. He looked so perfect beneath her, moaning and writhing in pleasure, the perfect mate.

,,,,,,,,,,,,,,,,

Sam hadn't answered his phone in weeks and now he simply turned it off and dumped it with the laptop he ignored as well. He was reacting very well to his training, all of that intense focus now on her. He'd become aware of her ability to influence him but by the time he did he didn't care. It felt….good, right, to let her do it. Even as he thought that he felt a slow, steady warmth filling him, body hardening. He went to the bedroom to find her waiting for him and kicked of his clothes to join her, eagerly offering his throat. There was a very obvious mark on his neck now and her fangs slid in easily and Sam let everything fade away as the most intense pleasure imaginable flooded his body.

,,,,,,,,,,,,,,,,,

Ruby smiled as Sam walked through the house, stark naked and uncaring as he walked towards her only to kneel before her. She stroked his hair and he sighed in pleasure at her touch. She knew she could never have anyone but Sam, no one else would ever be worthy and the urge to claim him was growing stronger and stronger. And Lilith, well she just didn't seem that important anymore. "I think you're ready Sammy," she whispered, and he hummed softly. "I want you Sammy, will you be my mate?" she asked, and he moaned.

"Yes, please Ruby."

She pulled him up, kissing him hard and Sam surrendered to her. "Bed, now." She ordered and he got up, practically running to the bed to lay down for her. he offered his throat and she sank her fangs in but this time the fluid that rushed into his blood was different, it still flooded him with pleasure, but it moved through his body, beginning to change it. Sammy writhed beneath her, eyes rolling back as he gasped and moaned, orgasming over and over before his body jerked, strange heat pooling low, almost burning. She switched to pumping in the pleasure fluid, not wanting him to really feel the burn as she had. Sammy whimpered weakly and she pulled off his throat to kiss him, licking at his teeth, smiling as she felt fangs forming. Soon he would no longer be human but her perfect mate and she couldn't wait to see him swollen with her spawn. She'd never mentioned that to him in the early days when he could have said no.

Finally, it was done, and Sammy blinked dazedly at her before smiling and reaching for her. "Ruby…mate," he purred, and she laughed before kissing him.

"My mate." She bit down again, feeling his fangs slide into her flesh for the first time and oh, it was better than anything she'd ever felt before. When his body reacted, she slid onto him but this time when he orgasmed, she felt no fluid come from him, his body now as incapable of breeding like a human as her own. They got lost in the continuous loop of pleasure for a long time before she felt the change, her fangs feeling heavy, the fluid now being injected very different to anything else she had given him. She finally pulled back, his fangs sliding free as she did and she stared down at him, seeing the instinctive knowing in his eyes. Within his blood, moving through his body to where they would be nurtured low in his body, were their brood. It felt perfect to both of them for this to be happening.

Ruby really should have been more careful in dealing with such old beings but now even if someone told her what she had done, she wouldn't care. All she cared about was her mate and their brood and he was the same.

The End.