Title: It Must Be Tuesday
Rating: G/PG
Summary: Sam figured you knew the apocalypse was coming when Dean got knocked out by a ninety pound girl.
Characters: Sam, Dean, and River Tam (Firefly/Serenity)
Disclaimer: Not mine. I mean, if they were, the show would be pretty different (well, not too different but there'd be my stuff…). Some pieces of dialogue taken from the movie Serenity.
A/N: Yeah, you read right. River Tam meets the Brothers Winchester. She's more lucid, like she was at the end of Serenity. No time travel or anything. She just grew up in this time.

Prior knowledge of the Serenity!verse isn't neccasary but it might improve your enjoyment of this story. This will be a multi-fandom crossover later on

I.

Sam figured you knew the apocalypse was coming when Dean got knocked out by a ninety pound girl. It was funny, but it was also… concerning. Maybe it was Dean's unwillingness to hit girls. Maybe it was the fact that he was still in shock from seeing her knock out a biker three times her size with a roundhouse kick and render two others useless at the same time, among other things.

Those in the bar who had yet to draw her attention fled as soon as she jump kicked two patrons in the chest before flipping backwards, immediately sweeping the feet out from under another person.

"Eta Kooram Nah Smech!"

Sam wasn't sure why he said those words. He wasn't sure where he had ever learned them, but they came to him and they worked. Her eyes closed, the pool cue dropped from her fingers and she dropped to the ground. The bar was silent except for Dean's groaning as Sam picked his way over the unconscious bodies to stand over her. Long, wavy hair spread out around her head, her chest rising and falling gently.

There was no lengthy debate in his head. There was never a question of what he should do. Sam only bent down and gathered the sleeping girl in his arms. For the damage she had caused, the girl was surprisingly light and delicate.

"Dude, what the hell are you doing?" Dean whined, using the edge of the bar to pull himself up. "We are not taking her with us."

"Get the manacles from the trunk."

Dean opened his mouth to object but Sam was already out of the bar.

II.

"Chaining anunstable killer woman to the sink is exactly what we should be doing with her," Dean grumbled sarcastically, but locked the manacle on her wrist. The clinking of chains filled the tense silence following Dean's statement. "How do we know she's not gonna break out?"

Sam reached for the antiseptic and started to clean the cut on her forehead. It wouldn't need stitches but would leave an impressive scar. "She doesn't have super strength. Just uses the situation to her advantage." He bandaged the cut up, tossing the tape back into the kit.

"Use the situation to her advantage," he mimicked. "You're taking care of her like a kicked puppy—"

"She's chained up, isn't she?" Sam bit out, giving Dean a look before gently taking her bruised and bloody hand to clean the busted open knuckles.

Dean was quiet after that and he watched his brother in silence for several long moments. "You had a vision about her, didn't you?" It was quiet, understanding. Sam's silence was the only answer he needed and he breathed slowly, running a hand through his hair. "Great."

III.

The rattling chains woke the brothers from their restless sleep and they immediately looked over to the bathroom. Dean carefully reached over to grab the tranquilizer gun. Sam hated to admit that the gun was necessary but precaution was usually beneficial.

As they peeked around the corner, the girl was leaning against the side of the tub, looking at her bound wrists with what could be described as detached curiosity. Sam glanced over at Dean who was cautiously lowering his gun a little. It was Dean who spoke first.

The girl didn't respond for several long moments but then she looked over at them. She was pretty in a slightly otherworldly way. Dark doe eyes watching them, calculating, shining in an off-kilter way. She looked back at her wrists, her wavy hair curtaining her face. "Not a demon. Just a girl," she said plainly, sounding a little lost.

"What's your name?" Sam asked, shrugging off Dean's grasp to near the bathroom. She looked at him warily but didn't shy away.

"River."

IV.

"World's gonna end soon."

Dean raised an eyebrow and River tapped her temple. "Saw it. Not fun. Might be zombies," she whispered, as if telling him an important secret. He would've taken her more seriously if she wasn't perched on a stone retaining wall in a airy purple dress with a little bit of vanilla ice cream on the tip of her nose.

"Thought the world would end in fire."

River shook her head, the ice cream still on her nose. "Some say in ice. Wouldn't be any fun in the fire. Can't fight fire but you can fight zombies just fine."

She had a point there, and as Dean looked away, he saw Sam smile and wipe the ice cream off her nose.

V.

River trusted both of them as far as she could throw them. Which, in all probability, was pretty far, but Sam was the one she chose to sleep beside. Dean supposed it was that whole 'Two-psychics-bonding' thing, not that he was complaining. No offence to Sammy but he really didn't feel like sharing a bed with his brother and no one really wanted to sleep on the floor.

Sam seemed to sleep better with River by his side anyway. More than once, Dean saw Sam pressed against her back, arm casually thrown across her waist. He made no comments about it and Sam didn't seem to care.

Dean wondered if he slept with Jessica like that.

VI.

River didn't speak about the world ending anymore, realizing that it made Dean antsy. That and the threat of duct taping her mouth shut and locking her in the trunk. The glare that Sam sent his way almost made him think twice about retracting the threat.

Almost.

Sometimes though, Dean heard Sam and River talk about it. Dean couldn't really make out what they were saying the nights neither could sleep but Dean knew that Sam's visions were worsening.

He could hold his little brother's hand as he shook eyes unseeing as the vision became more intense. He didn't realize how much he missed protecting his brother, how empty he started to feel since River arrived until Sam gasped out, "You've always taken care of me," before he passed out.

Dean watched Sam's breathing even out, becoming less erratic and his body relaxed. His shoulders sagged after Sam seemed to return to normal but he continued to hold his hand. A small hand grasped his shoulder, a soft kiss pressed to his temple and Dean slowly turned his head to meet her eyes. "My brother always took care of me too," she whispered.

They stared at one another, those simple words conveying so much before she left, leaving Dean to watch over his baby brother.

VII.

Dean woke up screaming the day the apocalypse started.

He sat gasping, drenched in a cold sweat and he looked around frantically, not quite sure what he was looking for. He finally stopped, eyes resting on Sam and River. They sat on the bed opposite. Her head rested on his shoulder, Sam's hands held hers. "You," he panted, looking at River who met his eyes unblinkingly. "The end of the world. You started it."

She rolled her eyes, something that seemed out of place in the conversation but completely River. "I had to prepare you," she said. Her voice was soft but it sounded deafening. "Had to make you ready. Put you through the motions."

Dean's mind tried to wrap around her words, and he swallowed harshly. "Every job… was the motions." His thoughts were running rapid. Prepare him… did that mean that this was the reason his father vanished? Was this… this the reason his mother died? He felt shaky, sick to his stomach and he couldn't look at River and focused on his brother instead. His baby brother who met his gaze sadly. "Your visions… they were all for this, weren't they?"

A wry, ghost of a smile graced Sam's face and he shrugged lamely. "I'm your back up. You're the special one."

VIII.

Why? Why me?

I looked into your heart and you just stood out from all the rest.

Why did you see in my heart?

A young man with an important purpose. A job to do. And it isn't finished.

IX.

"He's got the weight of the world on his shoulders," Sam said quietly, leaning against the railing, watching his brother in the training room below. Months since the end of the world started. Who knew so many people like them were around banding together to fight?

They'd arrived in Cleveland to find a rag tag army of other hunters like themselves, psychics like Missouri (who still had yet to be found), and those who had sought refuge having no idea what was really going on.

Their father had not been among them.

He gripped the railing a little tighter. "We always thought I was the special one," Sam whispered. "The one with the visions. The one the demon was after but it turned out that Dean was the one they were going for all along." He watched his brother walk among the lines of people, directing them on what they had to do.

Dean had to lead them all.

"The Apocalypse's Great General." Sam looked over his shoulder. "I'm just the one that tells him what's going on. The satellite TV."

"He'll protect us," River told him, slipping her hand in his. Sam looked down at her, their eyes locking. She smiled. "He's the big brother. Big brothers take care of us." She turned away to look back down at Dean, but Sam kept looking at her.

"I guess you already know what I'm going to say."

River shrugged, glancing back up at him. "I like to hear you say it."

"I love you."

Will there be more of this? Possibly. Will we learn about River's past in this universe? Probably. OMG Did I kill Simon Tam? Yes. OMG is Dean shirtless in that last scene? Of course ;)