Disclaimer: I am not affiliated with ABC or the Alternative Travel Project in any way. No profit is being made from this story. All ideas and opinions expressed are my own. Characters belong to ABC & AWM. No copyright infringement is intended.

A/N: This is a writing experiment: a light-hearted one-shot highlighting the many benefits, both personal and social, of Stana Katic's 'Alternative Travel Project' through the medium of the ABC TV Show 'Castle' and its characters. If you're not familiar with it you can check out Stana's initiative at alternativetravelproject dot com

Walk With Me

The story of what happened the day Beckett persuaded a reluctant Castle to 'ATP' to work...

[Outside Castle's loft. Daytime]

"Where's your car? Kate, did…did someone steal your car?" asks Castle, scanning up and down the street in both directions, Crosby and Broome, where she usually has no trouble finding a parking spot when she arrives at his place late at night.

"Relax, Castle. I left it at the precinct."

"You…? But you took a cab here, right? Because you didn't get to the loft until after eleven last night."

"No. I took the subway," she replies patiently, as if addressing a rather slow child.

"The…? At night?" he squeaks. "Are you crazy?"

"No. I'm armed. Now, stop fussing."

"Fine. I'll get us a cab. But this discussion is not over," he says, pointing fiercely at her before heading for the curb, until she snags the back of his jacket and pulls him back.

"Forget the cab, macho man."

"Yeah, you're right. I'll call my car service."

Kate takes the phone out of his hand and hangs up the call he's about to make.

"What? What are you doing? We're going to be late."

"Sadly, that mountain of paperwork that's awaits us isn't going anywhere soon. Come on. Walk with me," she says, turning right into Broome Street before he can even answer her.

"Uh…care to share where we might be going and why?"

"Subway station over on Spring and Lafayette. We can catch the six train."

"You want us to take the subway to work? Beckett what's going on?"

"Nothing is going on," she denies, hitting the sidewalk at a healthy clip.

"Look if you're on an economy drive or something…" he says awkwardly, since they never talk about money, "I mean I can always cover the cab fare and if you need a little extra…"

"Castle!" snaps Kate, shutting him up instantly, since he knows both that look and that tone. "I am not doing this because I am short of cash. Okay? We're…we're doing it because it'll be good for us to walk for a change, get some exercise…and…and we'll be doing our bit for the environment," she adds more quietly, almost as if she's a little embarrassed.

"The environment? Since when have you been a tree-hugger?" he laughs, only shutting up when he sees that she's actually being serious.

Kate scowls at him and then takes off along Broome Street at a pace he has to jog to keep up with. And yet again he marvels at just how fast she can go in those heels. It's like an actual superpower.

"I…Kate, wait?" he whines, getting a little wheezy by the time they turn onto Lafayette. "If we're walking, can I at least hold your hand?"

"No. Someone might see us," Kate points out, feeling bad for denying him this simple pleasure, but valuing her job and her partner more.

"You mean Gates?"

"I mean someone. Now, hurry up."

He insists they take a short detour to stop for coffee at a little independent coffee shop on the corner of Crosby and Spring before heading down into the station. She pays, he complains, but he follows after her grinning when she hands him the cup with 'Kate' scrawled in black Sharpie on the outside and takes the one marked 'Rick' for herself. She swapped their orders with the young barista to make sure she got it right, and he thinks it's just adorable. This day might just be looking up after all.

They flow down the old narrow steps into the Spring Street station with a crowd of trendy, young, SoHo commuters, the warm, damp, earthy smell of the New York Subway system rising up to meet them. They look older and better dressed than the average subway user, if Castle were to profile the crowd, and with their combined height and Kate's good looks (he might even add his own to that mix if he's only sharing these thoughts inside his own head) they get more than a few admiring glances their way.

"Here, got you a MetroCard," says Kate, shoving the little flexible plastic swipe card into his hand. "Don't say I never get you anything," she jokes dryly, striding ahead of him towards the turnstile.

"You've been planning this," he says, hurrying after her.

"Castle, it's just a MetroCard. It's not like I'm kidnapping you and taking you to Aruba."

"Now that I would like," he grins, and Kate gives him the stink eye over her shoulder.

He takes two attempts to get through the barrier, since he hurries to stay close to her and the machine rejects his first try, jamming the turnstile stubbornly closed.

They're standing on the platform that'll send them Uptown when Kate's cell phone starts to ring.

"Beckett. Hey, Ryan. What's up?" overhears Castle.

She frowns, spins in a tight circle while she listens to the call, cupping her hand over the phone to keep out the ambient noise, and then she grabs hold of Castle's arm when the train approaches the station.

The wind whips through the tunnel and sweeps past the platform tossing Kate's hair and undoing Castle's careful hard work on his own coiffeur. He runs a hand through it to smooth it back down, adding yet another item to his mental list of reasons why they should be riding to work in a cab or her cruiser – a list he's been working up since he watched a man spit on the stairs on the way down into the station. TB is on the rise again he remembers reading somewhere…or was it typhoid?

"Karpowski called in sick," Kate tells him when she hangs up the call, interrupting his little germ warfare plan. "So, we're up. Body drop in Union Square. Dead guy found tied up in the bushes. Paperwork's gonna have to wait."

"So…head back up top? Grab a cab?" suggests Castle with a hopeful smile and a tilt of his head towards the stairs, slowly shaking his head in unison with Kate when she answers in the negative.

"Three stops and we're there, Castle. Much faster than trying to get Uptown through traffic at this hour."

So they board the train that speeds into the station like a silver bullet, forcing the earthy air past their faces in one great rush.

There's a seat for two near one of the doors. He tries not to look like he's making a dash for it before anyone else. He fails, she glares, so he stands and offers it to the obscenely pregnant woman he spots gripping on tightly to the handrail. And seriously? Who rides the subway when they're about ready to give birth, he thinks, immediately chiding himself for how irritable and uncharitable he sounds.

Her fingers in his back pocket startle him, and his hand rushes round to pat his pants, already assuming the worst – some low life pickpocket is trying to steal his wallet without him noticing. Well, the way they're stroking his butt cheek right now…yeah, not so darned subtle.

When he traps Kate's fingers in his pocket, he whirls round in surprise, finding his girlfriend-slash-partner grinning seductively at him, a pleased little, 'look what I just did when you weren't looking' expression on her face. And maybe this subway-riding thing isn't too bad after all, if it means Kate Beckett gropes him in public!

"Looking for something?" he asks, feigning innocence.

"Wouldn't you like to know," she parries, slipping her hand back into his pocket, her lower lip drawn between her teeth in that 'naughty-girl' look that he loves so much, eyes glittering dangerously in the artificial strip lighting that casts everything in a yellow-pink light.

He spots two seats opening up across the aisle, scans the carriage for any one-legged, blind, elderly, heavily pregnant commuters, and when he's satisfied that they're in the clear, he nudges her elbow and points.

They sit down side-by-side, her leg pressed again his, hip-to-thigh and all the way down to her knee, and then he feels her leaning the rest of her body against his side, and he chalks another mental mark on the 'Pro' column he's suddenly added to his 'Reasons for Riding the Subway' list.

When he looks up, there's a scary guy sitting opposite them, all staring eyes and wild, unkempt hair, and how the heck did he not notice this guy before he made her sit down here. The guy is giving him serious evils, flicking his eyes up and down and up and down Castle's frame, like he can't quite believe what he's seeing. The second the guy looks at Kate and then back at him again, he knows what the guy is doing…or at least he thinks he does. This guy thinks Kate is out of his league, Castle decides. In reality, the man is clearly just a crazy who wouldn't be able to tell what league Kate Beckett was in if you gave him her college transcripts, her payslips, her NYPD collar rate and her 401K. Castle, however, is projecting, and can't help trying to prove himself in front of this guy…or any guy that looks at him wrong for that matter.

He checks his watch first, sliding it out from under his cuff, until he thinks better of flashing a piece of expensive jewelry on the subway and retracts it under his fancy French cuff. He's busy making a better plan when he feels Kate's hand settle possessively on his thigh. He swivels his eyes to the side, making sure that it is indeed her hand before he reacts.

She slides her warm palm up and down his pants leg, but when he checks her face, she's still looking off into middle distance, almost as if she isn't aware of what she's doing. But this is Kate Beckett, and there is never a moment when she doesn't know exactly what she's doing, especially where public displays of affection are concerned.

When she lifts her hand off his leg he almost cries out in complaint, barely catching the sound and strangling it in the back of his throat.

"You okay?" she asks, moving instead to reach for his closest hand, withdrawing it from the little steeple he's made between his thighs, and then, lacing his fingers with her own, she settles their joined hands in her lap.

And suddenly his mind is made up – they are definitely travelling by subway at least once a week if this is the result. If she feels safe enough in this little subterranean bullet, hurtling through dark tunnels below Manhattan's traffic congested streets to hold his hand in public, who is he to argue?

"So…did Ryan have a theory about our stiff?" he asks, trying not to get so distracted by the warm pressure of her slender fingers between his own that he sounds like a complete moron.

"Later," she whispers in his ear, the low, intimate hum of her voice and the warm puff of her breath against his neck sending tingles down his spine.

Yes, Mass Transit is definitely the way to go, he decides, taking another swig of coffee and relaxing back against the seat.

When the train surges into Astor Place, the driver hits the brakes a little too hard, jolting the car, and he spills some coffee on his pants, the still steaming liquid only narrowly missing his crotch.

He curses, glances at Kate apologetically, finding her already pulling a bundle of Kleenex from her coat pocket, before automatically attempting to pat him down. Their eyes meet briefly, and they each realize how this might look in public, so she stuffs the bundle of coffee-dampened tissues into his hand and nudges him to finish treating the spot himself.

Sadly, this puts an end to the handholding.

Castle watches Kate study a little girl further up the carriage - her hair tied in pigtails either side of her head by vibrant pink and green ribbons, hand held firmly in her mother's as she bounces her heels off the edge of the seat, her little legs too short to reach the floor.

"Penny for them," he says, leaning in to speak quietly to his partner so that no one else will hear.

"What?" she startles, cheeks flushing an adorable pink at being caught daydreaming. "Oh, I was just…" she hedges, looking away.

"Just what, Beckett?" he teases, nudging her shoulder.

"I like to make up stories," she eventually admits with a sigh of resignation, glancing back at the mom and the little girl. "About other commuters. Where they're going and why. Passes the journey."

Castle likes this idea, since he's been doing it himself for years. But the thought that Kate likes to look at her fellow travellers in the same way that he collects people as potential characters for his books pleases him, since it connects them, as if more of a connection were even needed.

"So…tell me her story?" he asks, nodding discreetly towards the little girl.

Kate shoots him a look to check if he's being serious or just toying with her. He meets her gaze and nods slowly, letting her see that he is indeed as interested in her observations and storytelling ability as she is in his.

"She…uh…" she swallows, crosses her arms over her chest, frowns a little, then smiles nervously before she tentatively carries on. "She's five years old and today is her birthday. And she's on her way to American Girl Place to choose her first doll," she says, picking up speed and confidence as her thoughts start to flow and she forgets to be self-conscious about describing her imaginings to a published author – her favorite published author.

Castle smiles tenderly at her, watching the way her eyes flicker over the scene of mother and daughter, absorbing every detail with her trained detective's eye.

"Fond memory?" he asks, boldly recapturing her hand in his own, more pleased that he should be when she doesn't pull away.

"Not…not that store. But, yeah, my mom took me to FAO Swartz when I was six to choose my own Cabbage Patch Kid. I loved the whole adoption certificate thing. Made me feel so grown-up. So…responsible," she grins, turning to look at Castle when she feels him squeezing her hand tighter.

His reaction is involuntary, and it throws them both for a second, getting so sucked into her childhood memory that they briefly forget where they are.

Kate nods a little tightly, ducking her head down to look at her lap, and then she lets go of his hand, eyes facing forwards again.

Castle looks off to his right, spots a young guy with an iPod, watches his head bobbing in time to the beat of whatever song he's listening to. The guy is completely lost in his own world, insulated from everything around him by his music and the rhythmic tap of his beat-up Chucks against the vinyl floor, and Castle wishes he'd known about this trip in advance so that he and Kate could have shared a playlist on their way Uptown. He made one for them at Christmas. She edited half of it out, improving it with stuff of her own; songs and bands he'd never even heard of. He smiles to himself, remembering a drunken rendition of 'Start Wearing Purple' by Gogol Bordello that they performed in front of everyone at his New Year's Eve party. Kate was dancing on the table by the end of their raucous duet with his purple silk tie draped around her neck.

Next time, he thinks, warming up to there being a next time on the subway even more by the second.

Their stop arrives and they shuffle towards the exit along with everyone else, and it seems as if half the train is getting off at Union Square.

"Friday. Green Market day," says Kate, reminding Castle of the farmers' market that takes place in Union Square three times a week.

They emerge out onto 14th Street surrounded by a sea of people with eco-friendly canvas bags and reusable plastic, tourists with cameras strung around their necks like jewelry and students heading to the huge Barnes and Noble store on the north side of the square.

Kate hands Castle her empty coffee cup and he tosses them both into an open Dumpster near the mouth of the station, cleaning his coffee-stained hands on the remainder of her tissues.

They cross the street and enter the large, open square, climbing the shallow steps that lead toward the small green space in the center, dodging a couple of kamikaze skateboarders along the way.

Esposito strides towards them from under the yellow crime scene tape.

"What? No coffee?" he asks, looking pointedly at Castle.

"In a dumpster one block back," says Kate dryly.

When Esposito gives her a curious look she explains some more.

"Someone had a little…accident," smirks Kate, nudging Castle in the ribs. "Spilled his coffee on the...train," she adds, pausing for effect.

Esposito follows her eyes towards Castle's damp crotch area and emits a little snigger.

"Bro, looks like you… Wait, did you just say train? What happened to your car, Beckett? Nah. Tell me it didn't get boosted from outside Castle's place."

"I'm right here, guys," the writer reminds them both, as they discuss his wet pants and his neighborhood without a thought to his presence.

"We're…what did you call it again?" asks Castle, giving Kate a look.

"ATPing," she repeats reluctantly, wondering if Castle wasn't listening to her at all or if he's deliberately setting her up for ridicule in front of Esposito.

"AT-what now?" exclaims Esposito, as they arrive at the patch of bushes, screened below some taller trees in the center of the square, where the body was discovered.

"A.T.P." repeats Kate slowly, prepared to say this only once. "Alternative Travel Project. It's…it's this green initiative I heard about. You take a car-free day a week, get fit, less stress, do your bit to help the environment," she adds, bracing herself for the jokes that are sure to follow.

"Oh, I heard about that," chimes in Ryan, surprising her. "Yeah, Mary Hart was interviewing some TV actress about electric cars on Entertainment Tonight. Stana something. I think she set it up."

"Katic," replies Kate quietly.

"Pardon?" asks Castle.

"Katic. The actress who set up ATP. It was Stana Katic," she repeats, wondering what she's opening herself up to.

"Y-you watch Entertainment Tonight?" asks Castle, staring at her, a wicked smile dawning on his face. "Wait. Is that what you were doing when I asked you to watch the lasagna while I took a shower and…"

Kate flushes scarlet. Busted!

"And you burnt it!"

"Beckett you burned Castle's lasagna?" taunts Esposito.

"Hey, how about Ryan watches Mary Hart? No one's picking on him," Kate points out.

"Actually, Jenny was watching," he shrugs, and they all shake their heads at him.

"Totally whipped, bro," says Esposito, his voice laced with disappointment.

"It was about electric cars," he insists lamely, trying to redeem himself.

"So you guys actually came to a crime scene on foot?" asks Lanie, pointedly looking down at Kate's fancy boots. "With those heels on? Girl, are you insane?"

"Beckett's idea," pitches in Castle, throwing his partner under the wheels of this particular bus without a second thought.

"We were on our way to the precinct to do paperwork. Okay?" explains Kate, giving Castle a look. "Subway got us here faster anyway."

"I can't believe you got Castle on the subway," laughs Esposito, giving the writer the once over. "Next you're gonna be asking Gates for matching push bikes with little blue flashing lights on the front."

"Actually," replies Castle, turning to give Kate a secret smile and the faintest bow of deference, "our journey had its charms," he admits, tugging on her coat pocket to bring her closer to him.

"You gonna run down our suspect on foot too?" teases Esposito.

"Do we even have a suspect?" asks Kate, archly, dragging her eyes away from her partner's warm, smiling ones to pin her coworker to the spot with a classic Beckett-glare.

"Well…we…no. Not yet," he admits reluctantly, glancing down at Lanie for help, though none is forthcoming.

"Right. Well, in that case, you'd better tell me what we do have. And if you say 'nada', Javi, you are walking everywhere for a week."

Fin

Some of the benefits of ATPing

- Help the environment by going car free one day a week to cut pollution

- Avoid traffic jams and lower your stress levels

- Get fit and get to know your neighborhood

- Enjoy the fresh air and take time to 'smell the roses'

- Talk to friends or catch up on the phone

- Watch the world go by

- Listen to music

- Drink coffee

- Daydream

- Save money

- Hold hands

Thoughts?