Notes: This veers off into a slight alternate universe in early season 4.

Extra special thanks to JillianCasey, Cora Clavia, shimmeryshine, and chezchuckles, all of whom helped me survive my ridiculous Week from Hell last week by writing and posting fic for me. (Yes, I do understand that I am stupidly, intensely spoiled. I am absolutely not going to apologize for this. Probably, actually, I am just going to keep begging for more fic.)

x

There's a moment when he's running, a jag of space and time, long after his heart has started thrumming fast and hard against his ribs and liquid fire has started shooting up and down his legs. It's when he's just pushing off the ground that the possibilities of the world rush and expand before him, and every step and every path is open, endless, waiting.

He didn't run over the summer. He wrote, some. He ate. He slept. Doggedly went to the precinct, every day, until he couldn't anymore. Slogged through publicity. Watched his phone. He developed this tic, actually, with it. Tapping it when it was in his pocket. Flicking the silencer off and on. Waking up in the middle of the night, reaching out, running his finger along the silver bevel. Two, three, a dozen times a night.

(He remembers the one time his phone froze for four, maybe five minutes. He hit the home button, tapped the power, frantically tried to reset it. His chest started aching, a ball of fire, twisting in his sternum, right where the bullet had –

Something in the phone clicked, reset. He went to the Apple store and bought a backup anyway.)

He doesn't need to touch the phone now, but he still wakes in the middle of the night. Reaching, reaching out for something that the sleek intersection of glass and metal can't satisfy.

It's three am and he thought he'd sleep soundly – Beckett, back in her chair, that and Alexis' recent benediction blanketing his rest (it's enough, he tells himself, she's alive and it's enough, he's with her and it's enough, more than he should have ever had a right to hope for). But he wakes with the same sense of desperation knotting in his sternum and knows he's up now.

There's a scale, in the bathroom, that he hasn't stepped on in maybe a year. He's a guy. Scales aren't for guys. But he's restless, idle, and he doesn't want to sleep, doesn't want to write, can't even bring himself to play angry birds (really, since she came back, he hasn't wanted to look at that phone). And so he toes onto it, and - when did he gain twenty pounds? Sure, he works out a little less than he had before he met Beckett, but he gets exercise, chasing after suspects, pacing in front of the murder board, even if he hadn't, exactly, this summer.

He puts on shorts and a shirt and unearths his running sneakers (the cushion must be shot, and he almost thinks twice about it all, but now inertia's on his side the other way – he's moving and damn if he'll stop now) and jogs out into the dead-of-night air. The city has just started chilling, the slightest snap and bite of fall, and he's off, no stretching, no warm up, just the pull of muscles long unused and the crack of his joints as he hits the pavement.

He almost gives up after what feels like a marathon but is really only six or seven long blocks. Pain shoots down his sternum like a mild heart attack, he thinks a tendon in his left knee might be popping out every time he pushes off the ground, his muscles burn with liquid fire. He slows, but a different ache starts in his chest, the same horrible, panicked desperation that he's been carrying for months, and it's enough to spur him on.

It's after maybe a mile and a half that he finds he's outrun it, that he loses everything but the rolling rhythm of the run, and even though after thirty minutes he collapses, chest heaving, against the side of a building, oh, does he wish he could go forever.

His life is shot through with purpose now. The rhythm of the precinct is back, the late-night phone calls, early-morning coffees, the constant background buzz of his brain trying to jigsaw the pieces of a case together. There's his writing, finally urgent again, the miniature Nicki back on his shoulder, whispering seductive suggestions in his ear at the most inopportune moments. There's Beckett, a little gaunt, skirting the edges of the darkness, Beckett, who he needs more than anything to save. And there's the pounding regularity of the run for when he thinks too hard about why he needs to save her, the overwhelming benediction of pain washing through his muscles.

"You're different," Beckett says as he hands her a coffee four weeks after she's returned. He'd run seven miles that morning. It only amazes him that he ever survived without it.

"Hm?" he responds.

"Different," Beckett reiterates, gesturing at him vaguely.

"Different," he echoes, trying to cock an eyebrow nonchalantly.

"Have you lost weight?" she asks. She has these bursts of directness, now, where the formerly-omnipresent filter between her brain and her mouth blips for an instant and she says things she never would have. He's hoping, some day, she'll let something important slip.

"Nice to know you're looking," he says, leering.

She glares and turns back to a file. Beckett used to run. It's not that she can't, now. Last week she ran down a suspect in a quarter-mile chase. She couldn't keep the wince off her face when she cuffed him.

He's not ready to talk about any of this. "The maid," he says.

Beckett glances up at him abruptly, but she's with him in a heartbeat. "She alibied out days ago."

"She's creepy," he responds.

"How many times do I tell you that I can't arrest someone for being creepy?"

He glares at the murder board, drums his fingers against a desk. "I don't see it," he finally says. He can make the edges of crimes line up in so many different ways that it's always frustrating when they won't fit at all. Gunshot to the back of the head. It's not even a weird one. "It should be easier than this."

The feel of her fingertips, cool and feather-light, brushing over the back of his hand, draws him back to her. "We'll get there," she says.

He runs another five miles that night, runs away from the memory of white gloves stained with blood, runs until the thread of stillness coils around him and he's alone in space with his muscles working and lungs pumping and her voice, echoing in his head, telling him they'll get there.

Two weeks later they're flat out after a suspect in Central Park when Castle overtakes her. He fumbles through a messy tackle and almost sprains his ankle and a fist glances off his jaw before Beckett's got the guy in cuffs, but he's puffed up on adrenaline and pride until they're loading the guy into the back of a squad car and he sees her face.

"What?" he asks, after Ryan and Esposito have pulled out with the asshole in their back seat. "We got him."

"You could have gotten seriously injured," she says, staring at him like he's a small, stupid child.

"I was being careful!" She just keeps staring. "You were right there!"

"I wasn't," she says. "I was a good thirty feet behind you."

"That's right there!"

"Anything could have happened."

"But it didn't."

She turns away from him. There's a park bench right beside her, and she folds onto it. He follows her, carefully, keeping six inches farther than he usually does. "I wouldn't have caught the guy," she says.

"Of course you would have."

"I was falling behind."

He's floundering; she's dropping threads and picking up others too quickly and he can't quite tell what's got her so off, the suspect overtaking her or him outrunning her or the vague glance of a fist off his jaw (it didn't hurt, earlier, but now he can feel the dull ache of a bruise forming). "I've been running," he says, redirecting the only way he can.

"I've noticed."

He almost questions her, but that would be stupid – six weeks and he's shed the extra twenty and is running a dozen miles a day, at the expense of sleep, at the expense writing, at the expense of everything but Alexis and Beckett. How could he have thought she wouldn't have noticed? "I see why you like it," he says.

"Yeah," she responds, just a sigh of air. Could he have said anything stupider than that?

"It hurts when you run," he says, pushing his luck further than he should. He can see it even now, though, the vague furrow above her eyes that means she's swallowing back pain.

"I'm fine," she says quickly.

He scales back. "I didn't really understand, before. I mean, I'd exercised. But not really – not to escape things."

"To escape things," she echoes, a little dully.

He's not explaining this right. "Or – not just an escape." He feels the odd sensation of embarrassment, deep in his chest, but he pushes on. "It's this sense of peace, this discovery of possibilities."

She's watching him intently. "I always thought you got that when you wrote."

"Writing's not peaceful," he tries. "It doesn't quiet things down – it turns up the noise." It's a frenetic, chaotic process, the opposite of the quiet wash of breath and pulse he gets at mile ten.

"I miss it," she says, and far beneath her matter-of-fact tone is a sharp edge of desperation. "I'm not so great at yoga."

"It's been such a short time," he says. "You'll get it back."

"It's been long enough."

"A hundred and seven days," he says.

She huffs a brittle laugh. "You marking a calendar?"

"No." He's sure he'll never be able to stop counting, that the significant markers for the rest of his life will be Days After.

"I want it back," she says.

He reaches out, trails a finger over the sleek fabric of her slacks at the top of her knee. "If I were faster…" He doesn't even realize he's said it until it's out of his mouth; as much as he's thought it, he's never really examined it as a motivation behind his sudden compulsion to run.

She smiles, chuckles, murmurs, "Than a speeding bullet?"

He's affronted. Here he is, confessing his deepest thoughts that his subconscious has hidden away, and she's laughing at him. "Are you really mocking me?"

She stops laughing, but a warm smile stays on her face, and it's impossible for him not to smile, too. She reaches out and lays a hand on his knee. Their forearms, extended towards each other's legs, touch lightly. "I'm glad you're running. You seem happy."

The brittleness has sheared away from both of them, leaving only soft smiles and easy touches. He thinks if they never moved from this spot, hands on each other's knees, forearms touching, somehow having pulled together after sitting so apart, that would be okay. "And sexy," he supplies helpfully.

He's waiting for an eye roll, but he gets the slow slide of her teeth over her lip, a darkening of her gaze as she watches his face.

"That, too," she says, voice low in the back of her throat.

Oh. This is not so good.

Are you sure? His brain provides, chivalrously. I know you've been through a traumatic time and there's that whole business about your walls and what have you and I wouldn't want you to feel pressured to start anything. But he can't say any of that, because somehow he's folded forward and brushed his lips over hers, softly, gently, too long to just be friendly.

He draws back, flicks his eyes over her, not sure how to voice any of the questions crowding his brain. "It's a good thing I've increased my stamina."

"Lucky me," she murmurs. He has never heard such a tantalizing combination of sarcasm and lust.

"Come with me," he says. She glances at him sharply, but the words have surprised him as much as they have her. There's nothing for it now, though, nothing for it but to plow ahead: "Not – not that. Tomorrow morning. Six am."

She's quiet for long moment before she glances down at her lap. "I don't know if I can," she murmurs.

"You can. We'll take it easy. Go slow."

Her teeth scrape slowly over her lower lip. "I don't think –"

He decides, abruptly, that he's tired of her thinking. "I'll be at your place at six. I'll do half the paperwork in payment."

She huffs. "You must be horribly desperate."

"Anything for a chance to run behind you," he says, leering a little, and then she's rolling her eyes and shaking her head but not quite protesting as she walks back toward the squad car.

"You're patronizing me," Beckett says after the first mile.

"What?" he asks. The morning air is sharp in his lungs, but it's a good kind of sting, revitalizing, a perfect counterbalance to the slow, trawling pace she's been trying to drag him out of since they started.

"I can walk faster than this. You're patronizing me."

No, he wants to say, you're still recovering, you weren't even sure you wanted to come, and what do you mean patronizing?, but he's sure that wouldn't be very compelling. "Just warming up," is finally the best he can do.

"You usually warm up like this?" she asks.

He hesitates, trips up in his too-slow rhythm and has to hop to keep himself upright. He's not used to dissembling in his Nikes in the dawn light.

Clearly, his silence is all the answer she needs. "Screw it," she says, "I'm going running. Feel free to come along."

He can't get another word out before she's off, long legs stretching out in a pace too fast to be less than a sprint. It takes him a moment to gather himself together, to organize and go after her, and by then she's flying down the sidewalk, momentum gathered, and it's six hard blocks before he can tuck in right behind her.

"Beckett," he puffs, "this wasn't really what I was thinking of when I suggested running."

She doesn't answer, just keeps up her frenetic, ridiculous pace. He wonders if she has strong enough meds at home, if she'll need to stop by her physical therapist's office for some electric stim to soothe her chest muscles, if she'll be in pain for the rest of the day, the rest of the week. He wonders if she feels it more than she lets on, if every day is a battle for her, a fight through the hurt, a war against her body. He wonders how she escapes whatever shredded memories she has of that time, or if she doesn't, if maybe she's taken off like this to try and find that inner stillness that comes from setting a fast rhythm in the clear, early-morning air.

"Beckett," he calls, then sucks in another deep breath before continuing. "Point proven! You can still kick my ass; I get it!" She doesn't even twitch in acknowledgement.

Sweat stings into his eye; he's overdressed, not prepared for this bout of exertion, but he's fine, keeping up, chugging along, until he sees her left foot hit ground an inch early, sees a flinch ripple down through her body, sees her head dip and then lift as she presses irrationally onward. He's suddenly, overwhelming, senselessly angry. He lets the anger spur him forward, over and around her, and then he cuts right in front of her and slams his momentum into a halt. Her body skids sharply into his, her knee smashing against his knee, her elbow into his stomach, her shoulder rolling into his chest. He stumbles back and sideways, back crashing into a sharp brick corner, the edge of an alley. He wraps his hands around her, snags an elbow and a hip, pulls her hard toward him to keep her upright.

He ends up pressed back hard into the brick, her body flung against him. "What the hell, Castle," she growls into his clavicle. She starts to push away, glaring daggers at him, her neck and shoulders glistening with sweat, vibrating with tension from anger or pain or some combination of the two.

"You needed to stop," he says. "You needed to stop and I'm done watching you run yourself into the ground."

He can tell she's still livid by the jut of her jaw, but she rolls her eyes at his words. He thinks, absently, how nonsensically he adores it when she does that, and it's annoying, infuriating, really, how even when he's so angry with her he can't stop loving her so desperately. And suddenly the warmth from her body really registers, the heat from her elbow and her hip soaking into his hands, rolling a hot wave of desire through his body. Her eyes are still narrowed in a glare, but there's a sudden weight to it, a heaviness that stills him, traps him.

He's not quite sure who starts it, lips suddenly crashing into lips, teeth scraping over tongues and hands sliding over sweat-slicked ribs, and the way she's running her nails over his abdomen as she shoves his shirt up and the way his hands are all on their own wandering higher and higher he knows nothing good can come of this happening in a public place.

She presses him harder against the brick, shifting closer, and somehow she winds up pressed against his thigh, humming darkly into his mouth as her hips rock against him. His fingers trip higher up, catch the slick bottom of a neoprene sports bra, and they're sweaty and clothed and in public and the only thing in the world he can bring himself to want is her naked and arched beneath him, middle of the sidewalk in Manhattan or no.

A loud crack snaps a wave of tension through them both. Their mouths break apart as a shudder runs through them together – just a misfiring car engine, he realizes, closing his eyes briefly, taking a deep breath. He feels all at once cold and out of sorts, his skin prickling from a combination of rapidly-cooling sweat and heady arousal. Beckett's chest jerks and stutters up against his, her breath too fast, uneven. He leans his forehead into hers, smoothes his hands down her biceps. Her eyes are blank with a quiet kind of terror; he maneuvers her carefully around so she's back against the wall, crowds into her, uses his body to shield her from the noise and light of the street. He's not sure how long they're like this, his hands cradling her elbows, his body arced protectively over her, his lips resting against the crown of her head. Finally, finally he can feel it, her body stilling, the jackrabbit hammers of her heart slowing steadily, the deliberate dragging of her exhale.

"What are you running from?" he hears himself murmur. She closes her eyes, her lashes a breath away from his, and shakes her head slowly against his. "Running toward," he pushes, feeling her breath hitch beneath him.

"Doesn't matter," she murmurs, "not quick enough to get there."

His tongue still burns with the taste of her, his abs are still smoldering from the trails of her fingers. "You're plenty quick," he says, unable to stop the smile from spreading across his lips.

She thumps him, hard, in his side. He shifts back, ducks his chin to look into her still-shadowed eyes.

He tilts toward normalcy, leans toward anything that will let some of the light leach back onto her face. "Oof, ow, don't brutalize me, Beckett. Maybe not plenty."

"I've been holding you back, though," she whispers, too much earnestness in her gaze, her muscles tightening under his arms. "Since – since," she says, letting it trail into its own sentence, no explanation necessary, no need to say since that moment one hundred and eight days ago when both their hearts stilled for several beats too long.

"No," he says, vehement, his fingers tightening around her arms as though he can inscribe the point into her skin.

"How do you do it?" she asks, letting her eyes slide shut, her muscles loosening as she sags back into the back wall.

"Do what?"

She lets out a frustrated puff of air, purses her lips. "Run without running at something."

He lets his hand slide down her arm, twines his fingers loosely through hers, brushes his lips light and dry across her forehead as he tugs her up from against the wall. "Let me show you."