Disclaimer: Not mine.

Author's Note: Of course I had to write this. Of course I did.

Many thanks to Cheryl for the beta.

Summary: Sam is five years old. Sam thinks he's Batman. Sam thinks Batman can fly.

Junior Justice League

The ER is a scary place when you're nine years old. It's big and noisy and full of people who are screaming or crying, full of the mingled smells of blood and disinfectant and the dispassionate voices of the nurses.

The ER is a scary place, and Dean's nine years old, but his little brother is five and has a broken arm. Sammy's been a trooper all the way to the hospital, sitting on Dean's handlebars with his arm clutched to his chest and a minimum of tears though Dean knows it must hurt him. Dean's so proud of him. Last week his classmate Jenny's little brother fell off his bike and scraped his elbow. He wailed so loudly the whole school heard, and he's a whole two years older than Sammy.

Dean didn't say anything, because Jenny has pretty blue eyes and thick glossy brown hair, but he thought her little brother was a crybaby.

The duty nurse gives them a look of disbelief when they go to the counter. Sam's clinging to Dean, good arm wrapped around him, face hidden in his blue Superman shirt, and she has to lean over the top of the counter to see him.

"Where are your parents?" she demands.

"Dad's at work," Dean says, trying not to let his voice shake. He's supposed to sound strong and confident when he's talking to strangers but Sammy's hurt. "I called him, he's on his way. But he said I should get Sammy to the hospital quickly in case it was more serious than a broken arm."

She purses her lips, eyeing the bat-symbol on Sammy's shirt and the big red S on Dean's.

"Let me guess. He was trying to fly?"

"It's my fault," Dean admits softly, hoping Sammy won't hear. The kid hasn't realized yet, and he'll probably hate Dean when he does. "I jumped first, but I was fine. Sammy's too little, and I wasn't watching him." He tightens his arms around Sam, heaving him up. He staggers a little, but Sam's small for his age, and his legs wrap around Dean's waist so they can both keep their balance. "Please. Do we have to wait for Dad?"

Sammy's head is on Dean's shoulder, and he turns it just enough to cast a pleading, tearful gaze at the nurse.

She softens, smiling. "Oh, sweetheart, of course you don't have to wait." She pats Dean's shoulder. "And I don't know exactly what happened, but I know it wasn't your fault. How about I take you both inside? The doctor'll be with you in a few minutes."

"Yes, ma'am."

"Let's get Sammy a wheelchair," she suggests. "Then you won't have to carry him."

Sam promptly clings to Dean even tighter.

And that's how they end up with Dean sitting in the wheelchair, Sammy curled up in his lap, being pushed down the corridor by Nurse Katie.

She takes them to the Paediatric Wing, where they're met by a smiling doctor who whisks Sam up out of Dean's arms and plops him gently down on an exam table. Sam's lip quivers, but before he can start crying Dean's up there next to him.

"That's fine," the doctor says, smiling. "Are you Sammy's big brother?"

"Yeah. I'm Dean."

"Hi, Dean. My name's Dr. Brenner. I hear your Dad's on his way here, but I don't think we need to wait for him to help Sammy."

"Is he hurting?" Dean asks, and his voice quivers a little. Sammy's so small, so tiny and fragile in Dean's arms, and Mom always told him it was his job to take care of his baby brother.

"I think he is," Dr. Brenner says sympathetically. "But we can fix that. Will you be my assistant?"

Dean nods eagerly.

"Great! I've got a really important job for you. I need to look at his arm before I take him into X-Ray. It's going to hurt him when I touch it. I need you to keep him still, or it'll only hurt more. Can you do that for me?"

"Yes, ma'am."

"Good boy. You want to get him comfortable first?"

Dean nods, and he takes a minute to hold Sam close. His throat tightens. This is one of the times when he really misses Mom. He doesn't remember her very well, but he remembers her perfume and the way she'd hold him and rock him if he fell down.

Sammy's never going to have Mom to hold him when he's hurt. But he has Dean, and he fits just fine in Dean's arms.

Dean doesn't know how to whisper all the sweet little things that Mom did to him, about how he was her boy and she loved him and she'd always keep him safe. He tucks Sam's head under his chin and says the only thing he knows how to say.

"It's OK, Sammy. I'm here."

It's enough to make Sammy settle down. He whimpers when Dr. Brenner touches his arm. Dean kisses the top of his head. It's a little girly and Dean knows he's too old for it, but he'll make exceptions while Sammy's hurting. Especially since it was his fault.

"It's definitely broken," Dr. Brenner says after a moment. "I think it's a clean break. We'll take him down to X-Ray and then I'll know for sure."

She doesn't let Dean sit with Sammy while he's being X-Rayed. He waits impatiently for the techs to finish, and as soon as they open the door he gathers Sammy into his arms again. They sit in the wheelchair together for the ride back upstairs.

When they get there, Dad's arrived. He's frowning a little, and Dean can't help wincing, wondering if he's going to be in trouble. He was supposed to be watching out for Sammy.

"How is he?" Dad asks.

Sammy presses in closer to Dean.

Dad sighs. It makes him look a little sad whenever that happens, when Sam bumps his head or burns his finger and runs to Dean instead of him. Dean's old enough to notice that.

But Dean's never tried to encourage Sam to go to Dad instead. Maybe it's selfish, he doesn't know. Ms. Miller, his teacher, says selfishness is wrong. But Dean can't help it. He misses Mom, misses her so much it hurts sometimes. And Sammy's a little bit of Mom, the last little bit of her left.

"I think he's comfortable," Dr. Brenner says tactfully, though she looks a little thoughtful. "Dean, can you help Nurse Linda get him up on the table?"

She goes out. Dad follows. Dean and the nurse get Sam situated on the table. The nurse does most of the work, Dean just holds Sammy's hand and squeezes it when he flinches or hisses.

A man comes in and straps a mask over Sam's face.

"We're putting him to sleep," he explains to Dean. "So he won't feel it when Dr. Brenner sets his arm."

Sam looks scared, so Dean scrambles up onto the table next to him. Nurse Linda tells him to get down, but he ignores her. He lays his hand on Sam's chest, feeling his heart going faster than it should.

"It's OK, Sammy," he says. He's said it so many times today. "I'm here."

Sam falls asleep slowly, and struggling every step of the way. Eventually he's under, and Dr. Brenner comes in and sends Dean out to wait with Dad while she sets Sam's arm.

"What happened?" Dad asks.

It doesn't occur to Dean to lie about this. Dad's probably going to punish him, but he deserves it. He let Sammy get hurt. He let him jump off the shed when he's much too little, and he didn't catch him.

To his surprise, though, Dad just shakes his head when he's heard the whole story. He doesn't look mad, just like he wants to smile but knows that would be a good idea.

"I'm sorry," Dean offers, just in case.

Dad shakes his head again. "You're not in trouble, kiddo. Kids of Sam's age get into all kinds of trouble. I shouldn't have left you alone with him."

Dean almost cries, because he doesn't want Dad to think he can't be trusted with Sammy.

Dad seems to guess what's in his head, because he says quickly, "That's not what I meant. It's just that Sammy needs two sets of eyes watching him, not one. He might've broken his arm even with me watching. Kids do it all the time, Dean. It's nothing to worry about."

Dean isn't convinced. Fortunately, he doesn't get the chance to argue, because Dr. Brenner comes out to tell them it's all done and they can take Sammy home.

Sammy's just starting to stir when they go in. The doctor's telling Dad something about proper care and not getting the cast wet. Dean doesn't listen. He stands by the table and pats Sam's good hand.

Sam opens his eyes a tiny bit. Dean's not sure he can see anything, but maybe he's not awake enough for that. He's about to ask the nurse to help him get Sam off the table, but before he can, Dad reaches over him and scoops Sam up.

"Come on, Dean," he says easily. "Let's get your brother home."

Dean's upset, though he tries not to show it. It never does any good to argue with Dad. But he should be holding Sammy. Sammy's just waking up, and he's hurt. He'll want his big brother.

Unless Dad really is mad that he let Sammy get hurt.

He bites his lip.

He practically has to scamper to keep up with Dad's long strides. The Impala's in the parking lot, and Dean can't help smiling at the familiar sight. His bike's already loaded in the trunk.

When he goes for the front door, though, Dad stops him. "Get in the back."

Dean grips the handle so hard his knuckles go white. Is this his punishment? He doesn't get to ride in front anymore?

Quietly, trying not to cry, he opens the back door and climbs in.

A moment later, he realizes why Dad wanted him in the back when Dad ducks down and passes Sammy to him through the open door. Dean holds out his arms and pulls Sam in gently, careful of the cast. Sammy opens his eyes long enough to smile drowsily up at Dean. Then he closes them again and curls onto his good side, snuggling into him.

"See?" Dad asks. When Dean looks up, he's grinning. "Sammy doesn't think it's your fault, either."

Dean nods, squeezing Sam. He looks down at the cast, plain green, and thinks about how cool it'll be when he writes his name on it. And maybe draws something. He can draw a dog. Sam likes dogs.

"Do you think Sammy'll want ice cream for dinner tonight?" he asks hopefully.

Dad laughs. "I'm pretty sure Sammy's big brother won't say no to it." He shuts the door and walks around to the driver's side. "Ice cream may have to wait till tomorrow, kiddo. Sammy might feel a little sick tonight."

"Tomorrow," Dean agrees.

After all, Sammy's warm and safe in his arms. He can wait a day for ice cream.

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