Disclaimer: Not mine.

Author's Note: This is for the Deals with Demons square of my hc bingo.

Many thanks to Cheryl for the beta.

Summary: There's a bar, and there's trouble. A little bit of speculation about S10.

Promise Me

The thing about being a demon is, it doesn't change who you are.

Dean's realized that now.

Most demons are heartless douchebags because they were heartless douchebags when they were alive. That's why they got sent to Hell and then turned into demons on Alastair's table.

Of course, the humans who weren't heartless douchebags didn't get a good deal either. Angels aren't really an improvement on demons.

Dean scowls at his almost-empty beer.

The thing about being a demon is, it doesn't change who you are.

Most demons don't love because they never did. But if you cared about someone when you were a human – someone like a kid with big, melting hazel eyes, who's losing weight because he's not eating anymore and he thinks you don't notice because you're a demon when in fact you do notice because how can you not notice, and it's not like a body that big can sustain itself on lettuce like some idiots seem to think, and just because you're a demon it doesn't mean you don't know how to feed your little brother, and –

Dean's forgotten where he was going with that train of thought.

Anyway.

What being a demon does is to make you feel all the negative emotions a lot more. Anger. Hatred.

Jealousy.

Dean transfers his scowl to the bartender. Sam went up to the bar five minutes ago for a fresh round. The guy's kept him there for five minutes making small talk. How long does it take to pour two beers?

Dean isn't jealous, of course. That would imply that he's insecure, and if there's one thing Dean's sure of, it's Sam.

It's true Sam's not exactly happy about Dean's insistence that they wait until they've finished Crowley before Sam cures Dean. It's true Sam thinks he's reckless of other people's lives – not Sam's life, of course, but random third parties that Dean honestly can't see why Sam's so bothered about in the first place – and that he's colder and more uncaring.

But Dean's never been the touchy-feely type.

Besides, Sam was the one who walked right past him in the library two nights ago when they'd just finished arguing about the whole cure thing. Stormed past him without a hug or a pat on the shoulder or –

Not that Dean wants pats on the shoulder. He's just fine. Sam can sulk all he wants. Dean's going to sit here and enjoy his miserable warm beer that doesn't even taste good anymore, while Sam makes friends with the bartender.

Dean doesn't know what the bartender's problem is, anyway. Doesn't he have his own little brother to –

Oh, and now he's introducing Sam to some other guy, like he knows Sam or something. Guy looks like a good mark for pool, and they do need money, and Sam is good. Big eyes, and now he looks like a skinny little kid whose big brother starves him. Nobody'd ever suspect him of trying to hustle them.

Pool guy is looking over at Dean, frowning, and saying something to Sam.

Does he think Dean's deliberately starving Sam or something? Dean made Devil's Food Cake. Last night. Enough for at least eight people. And did Sam eat any? Or even appreciate the joke?

Well, Sam did eat some. Like a piece.

Who eats one piece of cake?

Sam, apparently, when he's trying to make himself look neglected so some douchebag in a bar will think Dean's starving him.

Pool guy turns, face catching the light.

Dean knows him.

That's not a mark for pool. That's Logan. Dad hunted with him a couple of times. Didn't like him much, and Dean doesn't like him much either. He's a good hunter, but there's something a little creepy about him.

He's slapping Sam on the back.

Dean's eyes narrow. Logan should know the rules. Everyone in the hunting community knows the rules. He's spent the last couple of weeks making sure everyone in the demon community knows the rules, too.

Dean's baby brother is. Off. Limits.

He gets to his feet, crossing the distance to Sam and Logan just a little too fast for a human.

"Logan," he snaps.

Logan looks him up and down, showing no surprise at his sudden appearance.

"Winchester. I was just catching up with Sam here. Kid's grown up well. He could use some more muscle."

There's a challenge in the older hunter's voice, and Dean bristles.

"You saying I'm neglecting my little brother?" he asks coldly.

"Dean!" Sam hisses. "Don't be ridiculous. I'm sure Logan wasn't suggesting –"

"No, actually, Sam, I was suggesting. I've been hearing rumours about Dean lately. They say he's more of a hard ass than usual. Getting violent. Not caring about bystanders. Makes me wonder if he even cares about his precious little brother. Maybe he gets off on starving you. Asserting his power, or whatever people like him call it."

Dean's about to respond, but Sam gets in first.

"Dean's fine," he says, in a voice that brooks no argument. "We're fine. I'm not exactly helpless. Goodbye."

Logan opens his mouth.

Dean punches him in it.

And then all he can think about is hurting, hitting –

There's yelling but he ignores it. He needs to make the son of a bitch bleed. He feels bones crack –

Someone's hands are on him. Dean hits at the person blindly, and hears a familiar voice cry out in pain.

"Sammy!" He's on his knees, helping Sam up. "I'm so sorry, kiddo, I didn't mean – can you stand?" Sam's holding his jaw, and Dean gently removes his hand to get a better look. "We need to get some ice on that." He helps Sam step over the groaning heap of Logan on the ground and sit on a barstool. "Ice?" he demands, turning to the bartender.

The guy's shaking his head. "Look, you guys need to get out of here before someone calls the cops."

Dean feels anger rising. "My brother's hurt."

The bartender leans over the counter to look at Logan, like anyone cares about him, and then at Dean.

"Your brother's hurt? What about the guy you just damn near killed?"

"Sam needs ice or it's going to bruise."

"What the hell did you think you were doing, anyway? Your brother had to pull you off him!"

"Ice," Dean growls. He's really getting tired of the bartender's annoying habit of harping on tangential issues.

"Get out," the bartender says, pulling a rusty-looking pistol from under the counter and pointing it at Sam.

Dean's blood boils. Was he not clear enough? Wasn't Logan enough of an indication? Is he going to have to make an example of the bartender too? What is it with these stupid humans who don't get it through their thick heads that anyone who threatens Sam is going to have to deal with Dean?

"Dean!" Sam says, voice cutting through the uncontrollable rage filling Dean. "Dean, it's OK. We can ice it at home. Come on, let's go."

Dean takes a deep breath.

Sam's right. They should go. Sam's eyes are already getting a little too big. He's nervous, Dean can tell, and he doesn't want Sam to be scared of him. He'll just have to come back when Sam's asleep and have a word with the bartender.

"Come on, kiddo. I'll take you home."

Sam's pissed enough that he doesn't wait for Dean to get in the car. He just slams the door and drives off. Dean rolls his eyes, and waits for Sam to get to a red light before he dematerializes and rematerializes in front of the Impala.

He stands almost on the front bumper, knowing Sam won't drive into him, even if Dean's technically immortal now.

Immortal.

His throat burns.

Being immortal while Sam stays mortal? Dean can't think of a single crime he could possibly commit, even as a demon, that would be bad enough to earn him that punishment.

Sam gets out and faces off with him.

"What the hell was that?" he demands.

"I lost control –"

"You lost control? You almost killed him! You can't do this, Dean. If other hunters find out, they're going to come after you."

Dean feels a little flare of rage. "Don't pretend this is about other hunters, Sam. This is about what you want."

"Yeah, you're right. I do want my brother back."

Dean's unprepared for how much it hurts to hear that.

"I'm your brother."

The words are out of his mouth before he can stop them, and he can't believe he spoke in that pathetic, pleading tone.

But Sam's eyes are softening, so maybe it's just as well.

"You're my brother," he says. Dean feels something inside him ease. "You'll always be my brother, Dean. But you can't stay this way."

"You think I don't know that?"

"Then let me cure you."

"What if that kills you?" Dean bursts out. "It's the last trial." Now that the words have started, he can't stop them. "We stopped the trials, and I thought it was over, but what if it kills you? I can't risk it."

"So you want to stay a demon? That's your solution?"

"No!" Live forever without Sam? Is Sam insane? "Just… let me kill Crowley and then – kill me?"

Sam's eyes darken. "Don't be stupid."

"I'm not going to risk you dying. And there's nobody else whose blood I would want anywhere near me, so –"

"You're not going to risk me dying? It's not your decision!"

"Well, I'm making it. I won't let you cure me, Sam."

Sam draws himself up. "You can't stop me."

"Did you miss the part where I'm a demon? Superhuman strength, supernatural powers –"

"I know." Sam takes a step forward. "And I'm Sam Winchester." He's standing almost nose-to-nose with Dean now. "You can't let your brother die? Well, I can't let my brother live as a demon because he's got some weird self-sacrificing idea about how he's going to protect me. I'm going to cure you. If you want to stop me, there's only one way you can do it."

Sam's hazel eyes hold Dean's gaze, and Dean knows he's right.

There's only way to stop Sam. And it's a way Dean would never take, not even as a demon.

Let Sam risk his life to cure Dean, or kill him to prevent the attempt. Dean feels desperately helpless.

"Sammy."

It's open begging, and Sam responds with a tiny, reassuring smile.

"It'll be OK, Dean."

"I couldn't live with myself if it killed you."

"I couldn't live with myself if I didn't try." Sam inches closer. "Please, Dean. You don't even know that it'll kill me. Maybe it's over. Whatever Gadreel did… Maybe it undid the rest of the trial stuff."

"What if it didn't?"

"Dean, please."

"Are you…" He can't keep his voice steady. "I'm sorry, Sammy. I never wanted this to happen."

"Don't be stupid, Dean. I know you didn't. But now we have to deal with it."

"But if it… I… I don't know how to live without you, Sammy."

"Look at it this way," Sam says, trying for a light tone. "No matter what happens to me if I cure you, it can't be worse than two hundred years in the Cage with Lucifer and Michael."

"Sam."

"Look, I know it's hard, Dean. I… I understand, believe me. But it is what it is. We have to try."

"I know. I… Sammy."

Dean puts everything he feels into the word, and Sam responds with a dewy-eyed smile. "I know, Dean."

"Sammy."

"So we'll kill Crowley, and then… You let me cure you."

"Fine. But I have conditions too."

"What?"

"I want you as healthy as you can be going into it. So you start eating what I give you. If you start getting sick you tell me right away. And maybe some vitamins –"

"Dean."

"Let me take care of you."

"All right." Sam reaches out and grips his upper arms. "All right. But once we've dealt with Crowley, you let me cure you."

"As long as you're healthy enough –"

"Dean."

Dean swallows. "OK. Fine. If you eat everything I give you and promise to tell me when you're sick, I'll take your word for it, after Crowley's finished, that you're well enough to try the cure."

Something tingles.

They're standing at a crossroads.

Dean reaches up, pulls Sam's head down, and kisses the top of it.

The thing that was tingling settles into his skin, tightening, gripping. He can sense Sam, like a presence in his head. He doesn't know if it always feels like this. Maybe it's just because it's Sam.

"It's a deal," Dean whispers.

He hears Sam exhale as he realizes what just happened.

There's a long silence. It's Sam who eventually breaks it.

"Dean?"

"Yeah?"

"If… If I do die, promise you'll… let me go?"

Dean shakes his head. "No. Never. I can't, Sam."

"Will you try?"

"I don't know how."

And there it is. It's the right thing and the reasonable thing, and maybe it isn't fair to Sam to keep dragging him back at prices he doesn't want to pay, but Dean doesn't know how to live without him. If Sam can't accept that…

"All right," Sam says quietly. "Then at least promise you won't lie to me about it."

Dean smiles. "I can do that."

This time Sam waits for Dean to get in before he starts the car.

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