Fic prompt:

a cashier or waitress is super flirty with Castle and Beckett is jealous
(originally I thought post Caskett but you can pick)

It's not often that their job required much travelling. The occasional day-trip to the borders of the city, or the next town over, but they were never usually sent anywhere that required an overnight stay. For that, she was glad. For many reasons: the main of which being the NYPD's tight budget. They'd cramp as many bodies into a single room as possible if it saved them a few dollars. And the rooms were never more than a 2.5 star rating. The last time they'd been sent out of town, Esposito had complained about the bed bugs the entire 13 hour car ride home.

So when the Captain gave her the orders to pack a bag - "You're headed to West Virginia!" - she was less than enthused. The blow was softened, however, by Castle's insistence that he should come with. She knew there was no way he would settle for a run-down motel and off-the-highway diner food. This road trip could go one of two ways.

One: Castle would insist on upgrading her too, and she would spend the night in 5-star accommodation.

Or two: she'd be stuck in a crappy room, but she would be stuck there alone.

Either option sounded perfectly fine compared to being holed up in a room with Esposito and Ryan.

The drive to the small town was longer than expected and, after seven long hours of driving, they were still at least three and a half hours away from their destination. Heavy traffic, road works and detours had her frustration levels rising dangerously high.

"What are you doing?" she mumbled under her breath as she glared at the car in front of her. They had, for the past twenty minutes, been stuck behind a car going significantly slower than the legal limit. And, with the never-ending stream of traffic coming the other way, they were yet to have an opportunity to overtake. "Get off the damn road," she grumbled, slightly louder.

"There's a gas station about a mile up the road," Castle mentioned as casual as possible, looking at his phone. "Looks like they have a diner attached. Maybe we could get something to eat?"

"It's past three," Beckett stated.

Castle looked up from his phone and glanced at her, confused. "Exactly."

They hadn't had lunch yet, the fact that it was already past three o'clock was exactly his point.

She spared a glance in his direction before returning her focus to the road ahead of her.

"So we may as well just wait until dinner?" she explained. Castle laughed, thinking she was joking. "What?"

"That's not how hunger works, Beckett," he exclaimed as if she had somehow offended him. "If I have to wait another hour I may die! Let alone another several hours!"

Beckett rolled her eyes. "Don't be so dramatic, Castle. You're fine." As if on cue, his stomach made some horrible sound that made her think he might actually be in physical pain. "Ugh, fine."

She pulled off of the highway once the service station came into sight. It was quiet, almost deserted, but it didn't look too shabby.

Castle practically jumped out of the car the moment Beckett pulled into a park and eagerly walked toward the diner door. Beckett shut off the engine and hurried to follow him, but when she got to the door he was standing with a frown on his face.

"What's wrong?"

He didn't respond, just pointed to a handwritten note taped to the door.

Diner closed. We apologise for the inconvenience.

Beckett sighed. Great. Now she would spend the rest of the drive dealing with a sulking Castle. Just what she needed.

"Why don't you just grab some snack food to tide you over until we find somewhere else?" she suggested.

Castle turned his head and stared at the open sign on the service station door. "Guess it beats starving," he grumbled.

The bell above the door chimed as they entered but the young woman at the register didn't bother to look up from her phone. Castle began to weave through the few small aisles of goods as Beckett headed straight for the refrigerators at the back of the shop. She pulled two cold bottles of water from the shelf before moving back toward Castle. There were very limited options available but he took his time browsing.

"Just pick something," she said impatiently. "It's not that hard."

"I just- I had my heart set on proper food. None of this is going to be even slightly satisfying," he complained.

"Fine. Don't get anything then."

She grabbed a pack of gum from the shelf and walked up to the counter, placed her items down in front of the cashier.

"Just these, please," she said with a smile.

The brunette bombshell looked up through thick, mascara-clad lashes. Her make-up was heavy, a little overdone for Beckett's personal tastes, but it was flawless; the kind of bold glamour you'd expect to find at some upper-class event, not on your local service assistant.

"Any gas?" the girl asked, obviously bored.

"Uh-"

"Fifty on pump one," Castle interjected as he dumped two packets of crisps, a block of chocolate and a bag of gummy bears onto the counter. "And these, please."

He looked up and smiled at the cashier, who suddenly seemed significantly more interested in doing her job. She scanned the items quickly, with a smile on her face. Beckett watched as the girls' eyes kept darting between the register screen and Castle.

"You're Richard Castle, right?" she eventually asked.

The low, bored tone of voice from just moments ago was nowhere to be found, replaced by a chirpy, joyful tone instead. By now, Beckett had become accustomed to women flirting with Castle but they usually weren't so blatantly dismissive of her presence.

"The one and only," Castle replied, a little too flattered.

Beckett rolled her eyes. The one and only. Who did he think he was? George Clooney?

"I've read all of your books," the cashier said, suddenly sounding breathless and lusty.

That caught Beckett's attention. She looked at the girl, watched as those mascara-clad lashes fluttered dangerously in Castle's direction. God, if they fluttered any faster the girl would be at risk of taking flight! She smiled to herself as she waited for Castle's response. She wondered how he would do it, how he would cautiously navigate this interaction. She knew he would be flattered by the attention - it was Castle, after all - but the girl was barely legal. She looked like she couldn't be much older than Alexis! He was going to brush her off, polite yet firm. He wouldn't entertain the idea of actually flirting with the girl, right? But when several seconds passed and Castle was yet to say a thing, Beckett's unintentional glare shifted from the cashier to her partner.

Anger washed over her as she watched Castle's heated gaze rake over the young woman's face and chest.

"Castle!" she hissed, without thought.

Both he and the cashier snapped out of their daze and stared at her like deer caught in headlights. Their stunned expressions morphed: the cashier's into a look of frustration while Castle's expression became all too smug for someone who was clearly in the wrong.

Beckett's cheeks heated and she fought to keep herself from trying to hide the inevitable pink flush. She cleared her throat and straightened her posture.

"Sorry, we're in a bit of a rush," she said to the cashier.

Castle turned his attention back to the cashier, too. "Boss Lady is on a tight schedule," he joked.

The joke alone was enough to annoy Beckett. The cashier's response was just the cherry on top of the aggravating cake.

The girl rolled her eyes and scanned the last of their items. "How fun for you," she said sarcastically. Then, she plastered an overly bright smile on her face. "That'll be $64.80."

Castle paid and, when the receipt printed, she quickly scribbled something down on the back of it and slipped it into the bag of snacks.

Beckett stepped forward and grabbed the bag before Castle had a chance.

"Thanks so much," she said with a forced smile.

Castle had to hurry in order to catch up with her stride as they headed back to the car.

"You okay?" he asked once he caught up to her.

"She probably wants you to buy beer for her and her friends," Beckett said sarcastically.

Castle laughed. "Jealousy really doesn't suit you, Detective."

Beckett glared at him as he stuck the pump nozzle into the car's filler port and wriggled his eyebrows at her suggestively. She groaned as she lowered herself into the car and slammed her door shut.

She waited the two minutes it took for Castle to fill the car, but her frustration didn't simmer.

"Jealousy?" Beckett repeated, once Castle had slipped back into the passenger's seat, as if she needed clarification on where the ridiculous accusation came from.

He didn't bite, though.

"Hey, can I have the bag?" he asked, his eyes glued to the white plastic in her lap. "I think she may have slipped a little something extra in there for me."

Beckett reached into the bag and pulled out the receipt, holding it just out of his reach. "You mean this?"

"Yeah." He swiped for the paper, but she tugged it away. He squinted his eyes to read what was written. "Anya. What a pretty name."

Beckett scoffed and rolled her eyes. With one hand she dumped the plastic bag in Castle's lap, with the other she crumpled up the receipt and tossed it into the back seat.

As she drove away, Castle just smiled to himself. He was enjoying this way too much.