The first time is more or less an accident. They’re sparring in Castle, which always leaves them both high on endorphins and more than a little horny. She usually ignores his hard-on, the same way he ignores the high flush in her cheeks and how her eyes sometimes glaze over when they’re in close, sweaty contact, dismissing it as a side effect of the training. After, Sarah usually takes a shower or finds Chuck or both, but something is different this time.
She’s frustrated, has been for months, because sex with Chuck is good - really good - but it’s slow and sweet and loving, and she needs more than that. Sometimes she needs hurried, rough, violent, and ‘rough and violent’ are not words typically used to describe Chuck, who gets uneasy when his hands tangle slightly in her hair mid-blowjob.
As Casey knocks her to the floor and follows, pinning her down, she realizes that he could do it for her, and in a daze she wrenches her hand loose and pulls him into a kiss. It’s sudden, way out of left field, but he doesn’t hesitate. It’s all teeth and dueling tongues and fight, and neither lets go. By the end she’s bucking up against him, and he’s grinding down to meet her. He pulls back, eyes searching her face.
“Intersect,” he growls, finally.
“Safe word. Intersect.”
She gapes, and part of her wants to punch him in the mouth for choosing that word, of all the fucking words in the world. On second thought, she realizes that it's less cruelty on his part and more a check on whether she knows what she's doing, so she nods curtly in assent, then punches him in the mouth anyway to make sure he gets what this is. He grins with his newly-split lip and kisses her savagely, leaving the taste of his blood on her tongue.
He pulls her yoga pants down one-handed while holding her hands above her head with the other. She wriggles loose as he’s opening his own pants, pushing him off her and pulling her pants all the way off so she can straddle him.
He takes it as a challenge and so they fuck like they spar, hard and unyielding, striving for dominance, no more than a few thrusts in the same position. He gets in a few good punches, so does she. He gets her up against the wall, finally, knocking the air out of her. When she gets her wits about her again, she wraps her legs tightly around his waist. He smiles, bites her shoulder hard and takes advantage of her shock to hook his arm under one of her legs, lifting it high, resting it on his shoulder and opening her absurdly wide, helpless in his arms. She’s never come so hard in her life.
They don’t talk about it. Sarah says, defiantly, as she’s dressing: “I’m not leaving him”. Casey grunts something in reply that might mean “okay” or “you’ll notice I didn’t ask you to” or “what the fuck do I care?” - or possibly just “see you later” - and leaves.
It’s been weeks of this, twice-weekly sparring sessions that morph into phenomenally rough sex, punches and kicks, bruises and cuts, pain and spectacular pleasure. Sarah feels like she’s in heat, always horny, never quite satisfied except for those long moments that still never stretch long enough, when they’ve thoroughly beaten each other up and Casey makes her come, ever harder, on the floor or up against the wall.
She tried to hide the bruises at first, but when Chuck noticed one and asked about it, he accepted her explanation that they were stepping up their training - "I think Casey's feeling his age", she said, rolling her eyes - at face value. She feels like an asshole for doing this to him, but rationalizes that it's just sex, a simple release, not a big deal.
Casey has her beat now, her back flat against the floor, quarterstaff against her throat.
He makes her kneel up, binds her wrists behind her back with the cord from the waist of his workout pants, tight enough that she feels it threatening her blood flow, the thin rope digging painfully into her skin. Then he pulls her pants down around her knees and pushes her forward, making her find a balance with her face a few inches off the ground. She’s soaking wet just from this, from the fight and being tied up and manhandled, and when he lands a hard slap on her buttock unexpected pain coils through her and mingles with her arousal. She shouts, can’t help it. He laughs, then, waits a moment to make sure she isn’t about to safe-word out and then hits her again, and again.
She’s always thought spanking was for other people, people who wanted to play at pain but couldn’t take the real stuff. Boy, has she been getting it wrong.
He spanks her for what feels like forever, until her ass is throbbing and hot, her throat raw, her face wet. Pain has mixed with pleasure, driving her higher and higher, and when he stops and reaches between her legs with a hand that’s burning hot and rubs her clit hard, orgasm rips through her, taking her breath away.
He pushes down his own pants and enters her smoothly. His pubes scratch the tender skin on her buttocks unpleasantly, and without her arms for support her head knocks against the floor with every thrust, but she’ll be damned if she is going to quit at simple sex when she’s just held on through the thrashing of a lifetime. It doesn’t take him long to come, either, and as he softens inside her he reaches around and rubs her clit until she comes again.
After, he unties her and massages her wrists a little, a show of care that she wasn’t expecting, before tying his pants back up and leaving the gym.
She has the upper hand this time. Casey's still sore from an altercation on their last mission and keeps dropping his left shoulder. When she's got him pressed into the corner, he lets his staff fall, an admission of defeat.
"Take off your pants and kneel."
He acquiesces, and tucks his hands behind his back without being prompted. She pushes at his shoulder (the right one, she might want it to hurt but there are limits) and he leans back, gripping his ankles. She can tell it's an uncomfortable position for him, but he doesn't complain.
She strips off her pants and straddles him. He grits his teeth, and a groan escapes him when she bounces a little, straining his already tautly pulled muscles. She smiles, because the pain and discomfort seems to turn him on just like her, and his cock is jutting between them, rock-hard and leaking.
She bites his shoulder, as hard as she can, and he groans deeper, spreading his knees wider, giving up on holding back. He lets go of his left ankle and pulls her close, sucking her nipple in and biting it through her top. She shouts, because her nipples are ridiculously sensitive, and he knows exactly how to handle them to make her writhe and moan and - on a couple of particularly memorable occasions - come. She pulls free, gives him a backhanded slap and groans when he reigns her back in and bites down hard on her breast in reply. She lifts herself just enough for him to slide home, and his eyes screw shut in pleasure, like they do every time he enters her. She takes it as a compliment.
She pushes his hand back to his ankle and starts riding him in earnest, holding on to his shoulders. He grits his teeth against the pain and bucks back up against her. She comes first, hard, and pushes away from him as soon as the last wave of her orgasm has rolled through her. He growls, frustrated by the loss of her tight heat around him. He was obviously close, but doesn't move and doesn’t say a word.
"Hands and knees," she says, and he obeys.
She opens the leather belt that's still slung loosely around her naked hips - not by accident - and caresses his buttocks with it, making him shiver. When the first blow lands, he groans. She falters for a moment, agape at the way he's offering himself up to her, before drawing back again, letting the belt land heavily. He leans into the strokes, spreading his legs wantonly, and she’s hardly seen something so erotic in her life.
She doesn't mean for the blow to come up short and land so low, striking sharply across the back of his balls, and the “shit, I’m sorry” is halfway out of her mouth before she realizes that his howl came from pleasure as much as pain, and that he’s coming in long, sluggish pulses on the floor.
He wipes it up with his shirt, and throws it in his bag. She's not sure if she imagines a soft "thanks" as he leaves.
She's extra hard on Casey when she's had a fight with Chuck. She has always preferred resolving her issues with a good round of unrestrained hand-to-hand, but it's not like she can do that with Chuck, she'd kill him.
She settles, instead, for going mercilessly after Casey, and it's always given her a certain hollow sense of satisfaction. Today is no exception. He's on his back, bleeding from his lower lip and a cut on his cheek. He's also going to have a hell of a shiner in the morning. She's straddling his waist, pressing her arm across his neck, just barely avoiding cutting off his air supply entirely.
"I give, I give! Jesus Christ, Walker, what the hell has gotten into you?"
Grimly, she thinks that it's more what hasn't gotten into her, but Casey doesn't care about her relationship issues and she doesn't want to talk about it, so instead she leans down and presses a bruising kiss on his split lip. He responds eagerly, lifting his hands to her hips and pushing her downward, settling her so their crotches align.
She rides him hard, and uncharacteristically, he doesn’t make a move to throw her off or try to assert his dominance. Instead, he moves with her, roughly working her nipples until they’re sore, making her climax twice before he finally comes with a groan, his eyes screwed determinately shut.
"You should spar with Bartowski," he says while they're dressing.
She nearly jumps in surprise. She never expects him to talk.
"He could use the training," he says, looking up at her briefly, then back down at the fastening on his pants.
"What are you saying?"
He stops, looks her in the eye.
He doesn't explain what he means, doesn't need to. He doesn't say why, and Sarah knows it doesn't matter. He picks up his bag and turns to leave.
"We could still just spar," she says.
He looks back at her and smiles, that all-too-rare genuine smile that makes him look younger, more care-free.
"No, we couldn't."
“Please,” she says as soon as he opens the door. It's been five weeks. “I need it.”
He grunts and casts a look over at Chuck’s door. “What does he think we’re doing?”
“Sparring,” she says like it’s the dumbest question anyone has ever asked her. “Casey…”
Her tone is pleading, bordering on pathetic. Deflated, he steps aside and lets her in. She has already started moving furniture to make a sparring circle in his living room when she realizes that he’s gone upstairs. She follows him up to the bedroom, and feels a lump in her throat as she crosses the threshold, because this is a whole new thing for them. They don’t do sheets and mattresses and sex like it’s sex.
“Strip,” he says from where he’s nakedly perched on the windowsill, and she does.
This isn’t their game either, they usually tear each other’s clothes open just enough to get off. It’s almost frightening, being completely naked under his gaze, seeing him naked, watching him giving her a once-over. He nods towards the bed and she gets on it, kneeling up. He smiles, which gives her a thrill, and gets behind her on the bed, stroking and touching much more carefully than usual.
She would push or squirm or kick to make him go faster, harder, except she feels distinctly off-kilter at the changes to their routine, so she stays still, closes her eyes and lets him do it his way. A murmur of arousal is whispering through her, but it’s nothing compared to how she’s used to feeling when she’s with him. After a while, he turns her to face the other way, still staying behind her. When she opens her eyes she looks right at her own reflection in the mirror, with Casey’s hands roaming her body.
“Is this what you want?” he says, and she’s startled, because he never talks when they do this.
He pinches her nipple, hard, and her “yes” disappears in a moan. He gets rougher, pinching and biting, slapping and squeezing, and finally, the thick haze of pain and arousal rolls through her. She loves this, all the things he can do to her, and watching it in the mirror excites her even more.
“This is what you want,” he says, and this time it’s not a question. “You want me to hurt you. Humiliate you.”
“Yes,” she yelps as he twists her nipples cruelly.
“All those things Bartowski can’t do for you. The stuff he wouldn’t even dream of, because he’s such a good little Boy Scout.”
She tries to move away, doesn’t want to listen to this, but he holds her firmly in place, and her arms are angled between them so it’s hard to pull free.
“You want this because you can’t even come with him anymore without imagining me doing this to you.”
The shock stops her cold before she can think it through. “How the hell do you know that?”
One look at his reflection tells her he was guessing, but he knows now.
“Fuck you,” she spits, and he smiles, darkly amused.
“I was thinking of fucking you, actually, but I suppose a little ass play never hurt anybody.”
She swallows heavily, not sure if he’s joking, doesn't reply. Finally, he shrugs.
“Oh Walker,” he says with a strange sing-song in his voice. “All talk and no follow-through. My way, then.”
He pushes his knee forward to spread hers further apart, pumping his fingers shallowly inside and using his thumb to toy with her clit. Her eyes drift closed, so she has no forewarning when he suddenly pulls her back and up and pushes inside her.
It's his favorite position, she thinks, having her splayed in his lap, back pressed to his chest, legs on either side of his. It gives him free access to bite on her neck and the expanse of her shoulders, to play rough with her breasts and nipples, bring her to the brink over and over by pinching and rubbing her clit.
She tumbles over the edge and leans her head back onto his shoulder to catch her breath. She doesn't expect him to pull back when he does, and the shift in balance makes her tumble off the bed.
The pain sharpens her pleasure, brings it into relief as it always has, but she has no idea what just happened. When she looks up at Casey, she's unsettled by the look on his face. They stare at each other for a long moment, before he stands up. For a moment, Sarah wonders if he already came, but one look at him makes it obvious he didn't.
"More," she says, feeling like a greedy toddler who's out of candy.
Their eyes lock again, and she wonders she’s imagining a flash of desperation before his face blanks and he offers her a hand up. Once she's on her feet, he pushes her towards the wall, but changes her direction at the last minute. The window is cold against her bare skin, and her nipples, already tight with arousal and sensitive from coming, ache with the sudden chill. Then, he presses in close behind her.
“Casey,” she begins, but he’s lifting her right leg high and twisting it sideways, resting her foot against the window sill, and pushes up inside her. Her whole body is pressed against the window, and she is looking down at the courtyard. Anyone standing down there who happened to look up could see her. At an angle, she can see Chuck’s bedroom window. If he were to look out and up...
“Casey,” she gasps. “We can’t --”
“Shut up,” he says. “Or I stop right now.”
His left hand is a vise on her hip, and he presses his right arm in between her and the window, burying his fingers in her slick curls. He’s pinching, pulling, kneading, and she can only whimper as he moves her in time with his brutal thrusts.
“You like this, Walker?” His voice is rough, but steady, a growl in her ear.
“Answer me,” he demands with a cruel pinch on her clit. “You like this?”
“Yes,” she groans, because she does. She hates herself, but she is getting off on this so hard, and he knows it.
“And to think Bartowski could just look outside and see you, pressed against my bedroom window with my dick inside you.”
She gasps, and he chuckles darkly.
“Think he’d like what he was seeing, Walker? That you’ve got someone else to give you what he can’t? Think he’d like seeing you come harder than he’s ever made you? What do you think he’d say?”
She’s coming again, and coming apart, shouting, thrashing around as much as she can caught between Casey and the window. He grabs both her hips and drives into her hard until he comes with a loud groan.
When he pulls out of her and lets go, she makes it to the bed before her feet give out from under her. He leans back against the wall and watches her as she tries to catch her breath. Finally, she trusts her body enough to sit up and glare at him.
“Are you insane? Anybody could have seen us!”
Casey shrugs. “I’m not the one with everything to lose, Walker.” He pulls his pants back on. “I wasn’t kidding before. I’m out.”
He disappears into the bathroom without a second glance. A minute later Sarah can hear the shower running. There’s something she’s missing, but she can’t put her finger on it. Casey has been acting more weird than usual since they stopped having sex, and today he was excessively, needlessly cruel, almost as if he was trying to push her away or --
The shock stops her train of thought cold, and something nasty twists in her stomach. Casey has feelings for her. There’s no other explanation that makes sense, or that could possibly be less convenient. Fuck.
She gets dressed in a hurry and gets out of there before Casey comes back. She doesn’t relax until she’s locked in her own bathroom, leaning against the cold tile and letting hot water wash every trace of Casey from her skin.