Stupid, Stupid Idea pt. 1 (Your Body)
Cassie McKay x reader
Summary: After Cassie asks if you need a ride home, and with much convincing from Trinity, Perlah, and Princess, you agree to the ride. However, it turns into something much more than a simple drive.
Word count: 4k
Warnings: SMUTT, thigh riding, praise, Cassie being a butch as she is, power imbalance, orgasm denial (maybe?), talking reader through it somewhat, age difference (reader is around 27, Cassie is 42-43 like she is in the show), Fingering (reader!receiving), swearing
🎵- Your Body
“She talks you through it, for sure. Praises you like crazy.”
That’s all you can think about after Trinity told you, as you stare at Doctor Cassie McKay from across the Nurse’s station. Your elbow leans on the counter as the ER gets ready for Night Shift. Half of the trainees have already gone home, aside from you, obviously. You pretend to be very invested in the laminated chart taped to the counter, but your eyes keep drifting up anyway to her.
Honestly? She terrifies you. You’re absolutely terrified of bothering her, of being too forward or inquisitive. You answer her when prompted, of course, but every time your heart beats tick up, and your hands begin to shake, which is not great if you’re cutting into someone as she stares down to make sure you’re doing it right.
You’re often hypnotized by the way she gestures with her hands, and thinking about all the impossible things you want to know but can never ask. And heaven forbid the last thing you want to do is accidentally test her patience, which could possibly get you abandoned and pushed onto Langdon or Doctor Samira Mohan. You wouldn’t mind Mohan, however.
McKay stands half-turned near the med cart, sleeves rolled up, hair pulled up with her bangs brushed out. She’s laughing at something a resident says—low, warm, and effortless—and the sound lands straight in your chest.
“I would pick your mouth up off the floor if you don’t want her to notice.” Perlah jokes, and you look down at yourself, realizing you’re practically drooling.
“Fuck off, I wasn’t even staring.” You grumble, wiping off invisible dust from your scrubs before resuming your position at the nurse’s station.
Perlah finally glances at you, one eyebrow raised in a way that says liar. “No, you weren’t staring. You were practically eye fucking her.”
“I was not.”
“Mmm.” She clicks her pen. “Anyway, how was it with her today?”
You hesitate, and that gets her full attention. You lower your voice even though Cassie is clearly across the room and very busy, not paying attention to you. “She asked me if I needed a ride home.” You wince.
She freezes for a moment before a smirk appears slowly on her face. “And you said…?” She asks, tidying up desks and papers, glancing at you from time to time.
You begin to bite your thumbnail, your eyes watching Cassie before quickly going back to Perlah. “Haven’t said anything yet.” Perlah stares at you, and you are quick to add, “I mean, I didn’t say yes. Or no. I just—” You gesture uselessly with your hands. “I nodded. And said, like, ‘I’ll think about it.’ Or something equally dumb.” You sigh, planting your forehead on the counter. “I feel stupid.”
Perlah bursts out laughing, head tipping back. “Oh my god. Just say yes!” Perlah wipes at her eyes. “She offered you a ride home, and you treated it like she asked you to refinance a mortgage.”
You lean your elbows on the counter, dropping your head into your hands. “I panicked.”
“Panicked about what?” Trinity asks, walking up to where both of you were standing around. Okay, well, you were standing around, and Perlah was actually trying to clean up.
You lift your head. “You know what.”
Trinity grins. “Oh, yeah. Say it.”
“No.”
“Say it.”
“I can’t! I mean, I can, but—” You exhale hard. “I don’t know. It’s hard!”
Perlah’s smile softens just a fraction, but she doesn’t let you off the hook. “It’s a ride. Not a marriage proposal.”
Trinity tilts her head. “Is it just a ride, though?”
You groan and point at her. “Don’t.”
Cassie shifts across the room, glancing briefly toward the counter, and your stomach does a very unhelpful flip. You look away immediately, heart pounding.
Perlah and Trinity notice, and they both smile.
“Okay,” Trinity says. “Let’s bring in a neutral party.”
You turn to Princess, who has also joined the group now. “What do you think, Princess?”
Princess blinks. “About…?”
Perlah sighs dramatically. “Alright…” She gestures between you and the general direction of Doctor McKay. “Our girl here has been silently pining since orientation. Doctor Cassie offered her a ride home. And instead of saying yes like a normal person, she said ‘I’ll think about it’ which is a very normal response, but when it’s someone you want to have… particular relations with….”
Princess’s eyes widen a little. Then she looks at you. “Oh.”
“Don’t say it like that.”
Princess considers you carefully. “She asked you specifically?”
“Yes.”
“And you, of course, work together.”
“Yes, obviously.”
Princess nods slowly. “I get it,” she shrugs.
Thank you, you think. Finally, someone gets it.
Perlah rolls her eyes. “You’re both acting as if she asked you to elope.”
“She’s my supervisor,” you say weakly.
“Technically, Robby is our supervisor. Not Doctor McKay over there, but yeah, she’s still pretty up there.” Trinity comments.
Perlah nods. “And she asked you for a ride. That’s casual.”
Princess tilts her head again. “Was it casual?”
You swallow. “She smiled.”
Perlah rolls her eyes but smiles anyway. “Oh, she smiled.”
You press your lips together, trying not to look across the room again. “I don’t want to make it weird,” you begin to bite your thumbnail again.
Perlah leans in, voice dropping. “You already made it weird by not answering.”
Princess nods. “Honestly? If you say yes now, it’ll just seem… thoughtful. Like you did consider it.”
You glance toward Cassie once more. She catches your eye this time—just for a second—and gives you a small, patient smile, like she’s waiting.
Your chest tightens.
Perlah watches you, soft but firm. “Just say yes.”
You don’t answer, and Trinity decides to comment again. “I mean, you have to tell her now, she just smiled at you, waiting.”
You go home imagining that smile. It’s on your mind when you pull into your apartment complex, exhausted and hungry. You try not to constantly replay the incredibly vivid memory of a patient saying something sexually obscene about you once, and how quickly the doctor whipped around and gave the person a deplorable look.
“Uh…that was…” You remember saying, looking at the now closed door of the patient’s room, to which McKay replied, “Uncalled for, yeah. I would’ve punched him if it wasn’t malpractice,” before taking off towards another person’s room.
You had to turn your head into your pillow to muffle the sounds you made from touching yourself later that night.
Good God, you want her. You want to help her relax, give her something soft and warm to come home to after exhausting days spent in this place, after dealing with Chad. Sometimes, during shifts, and well, especially at night, you can’t think about anything else besides how hard she’d fuck, how much she desperately needs it, how sexy her voice would sound gasping your name. You’ve heard her speaking to Dana about how she needs to get laid. She deserves an award for dealing with her stupid ex and difficult patients.
If she even returned your feelings by ten percent, it’d be gracious and far more than you probably deserve.
You don’t remember deciding to move.
One second, you’re still leaning against the nurse’s counter, Perlah watching you like a hawk, Princess pretending not to, and Trinity making comments in your ear, and the next you’re pushing off the laminate and walking. Each step feels too loud, like the floor might announce your intentions before you do. You feel like it should also swallow you whole.
Cassie McKay is by the break room now, leaning against the doorframe, talking to Mateo. He sees you coming over and quickly dismisses himself, probably mumbling something about having to clean up the break room or something.
You stop a few feet away and clear your throat. “Uh—Dr. McKay?”
She looks up immediately. “Oh,” she says, surprised in a way that feels genuine. Her smile comes easy, like it always does when she sees you. “Hey!”
Your brain promptly forgets every prepared sentence. Your tongue feels too big for your mouth all of a sudden. You barely manage to squeak out a “Hi!”
She waits. She just tilts her head slightly, attentive in a way that makes your chest feel too small for your heart.
You take a breath. “About earlier. When you—um. Asked. If I wanted a ride?”
Cassie’s expression shifts—not alarmed, not awkward. Curious. Open. “Yeah?” she says gently.
You force yourself not to look back at the counter. You already know Perlah is watching. You don’t need the pressure. “I’d like a ride home. I had to take the bus this morning, and it can be really scary at night, well, at least for me anyway, and well, I guess for you too, ‘cause you’re also a woman, but you have a car, so you wouldn’t know. No-not saying you wouldn’t-” you blurt but cut yourself off when you see her smiling broadly at your word vomit. “If it’s still—if you still mean it. If it’s still available, I’d like the ride home.”
The words tumble out clumsy and honest and irreversible.
Cassie blinks once while that smile is still on her lips. “Yeah,” she says. “Of course I meant it. It’s still up for grabs, and honestly,” she leans into you, and you can smell her perfume. Vanilla. That and antiseptic. You and Trinity had an ongoing bet to see what exactly she smelled like. You had your money on either vanilla or pomegranate—Trinity bet jasmine or oak. You win. “If it wasn’t for you, I would’ve had to take Yolanda home, and by home, I mean Trinity and Dennis’ apartment, and it gets awkward.”
You let out a breath. “Okay,” you say, quieter now. “Cool.”
Cassie’s smile widens just a little, something warm in her eyes. “Cool.” She shifts her weight, lowering her voice. “I’m parked in the south garage. I’ll be done in about ten minutes—does that work?”
“Yes,” you answer immediately, then cringe. “I mean—yeah. That works.”
She chuckles softly. The sound does things to you. “Alright,” she says. “Meet me there?”
You nod. “I’ll be there.”
Cassie hesitates, like she wants to say something else. Her gaze flicks briefly over your face, careful, thoughtful. “I’m glad you said yes,” she adds.
Your pulse stutters. “Me too.”
Another beat. Then she straightens, professional mask sliding back into place—not cold, just… contained. “I’ll see you in a bit,” she says.
“Yeah,” you reply, already smiling like an idiot. “See you.”
She turns and walks away, calm and unhurried, like she hasn’t just knocked the air out of your lungs. You stand there for a second too long, and then you pivot and head back to the counter.
Perlah is grinning so hard it’s almost unsettling.
“Say. It. Now,” she says.
You lean on the counter, dazed. “I said yes.”
Princess lifts her coffee in a toast. “Atta girl.”
Perlah beams. “Finally.”
You glance toward the south hallway where Cassie disappeared, your stomach fluttering with nerves and something dangerously close to excitement.
“Go get ‘em, tiger,” Trinity says.
“Shut up,” you mumble, smiling. The south garage smells like concrete and oil and the faint chill of evening air. Your shift bag hangs heavy on your shoulder as you pace near the elevators, trying not to look like you’re pacing.
You check your phone. No new notifications. You check the time. Too soon. You stop checking everything altogether at one point. You literally have to remind yourself to breathe.
Suddenly, footsteps echo from the stairwell, and you look up.
Cassie steps into view, coat draped over one arm now, hair slightly looser than it was upstairs. The fluorescent lights make her look out of this world, and her eyes find you almost instantly.
“Hey,” she says.
Your stomach flips. Again. Probably for the 100th time. “Hey,” you answer, suddenly aware of how small your voice sounds down here.
She walks over, relaxed but not careless, like she’s giving the moment the same respect you are. “Sorry—got pulled into a last-minute sign-off.”
“No, it’s okay,” you say quickly. “I just got here.”
Cassie nods, then gestures toward an old green Toyota Highlander a few spaces down. “This way.”
You fall into step beside her, close enough to feel her presence without touching. The silence is definitely awkward, but you can’t even begin to know what to say to fill the void.
When she unlocks the car, the lights flash once. She opens the passenger door for you.
“Oh,” you say, surprised. “Thank you.”
She smiles. “You’re welcome. It’s a habit by now.”
You slide in, nerves buzzing under your skin. The car smells clean, faintly like coffee and something clean, even if there are broken crayons and food crumbs in the seats. Cassie closes the door, then moves around to the driver’s side.
When she gets in, there’s a brief pause before she starts the engine. “So,” she says lightly, pulling out of the space. “Long shift.”
You huff a laugh. “That’s one way to put it.”
She glances over at you. “You held up okay.”
Something about the way she says it makes your chest warm. “Thanks.”
However, she quickly changes the subject as she turns on the heat. “It’s pretty cold in here.”
“Oh, yeah, yeah, it is. Freezing.”
You drive in silence for a minute, the hum of the engine steady, the garage ramp spiraling upward. When you hit the street, the city lights spill across the windshield.
Cassie clears her throat. “I hope I didn’t put you on the spot earlier.” Your heart stutters. “What do you mean?” You ask. “W-with the car ride thing? You’re good, don’t worry about it!”
She smiles, eyes on the road. “Good.”
You hesitate, then add, “I just… didn’t want to be an inconvenience.”
McKay laughs. “Inconvenience? I was the one who asked you.” Another pause. Then, softer: “I wouldn’t have offered if I didn’t want to.”
You swallow. “I know,” you admit.
She chuckles. “Then don’t say you thought you’d be an inconvenience.”
“Yeah.”
The car rolls through a yellow light. The radio is low—something mellow, instrumental. Cassie’s hands are steady on the wheel, sleeves of her sweater pushed up just enough to show her wrists. You force yourself not to stare.
She glances at you anyway.
“Where am I dropping you?” she asks. “Forgot to ask before we started driving.” You give her your address. She repeats it back, committing it to memory, then nods. “That’s not far from me.”
Your brain latches onto from me like it’s a gift. “Oh,” you say, trying to sound normal. “Really?”
Cassie smiles again, that easy warmth returning. “You live in a good area.”
You nod, then, without meaning to: “Do you like where you live?”
She considers the question. “Most days. It’s quiet. Which I appreciate more than I used to.”
You smile. “I can see that.”
She glances over. “Yeah?”
“Yeah,” you say. “You seem like someone who values quiet.”
Her expression softens, something thoughtful in her eyes. “You’re observant.”
You shrug, suddenly shy. “Occupational hazard.”
She laughs—really laughs this time—and the sound fills the car. Cassie reaches for the console, adjusting the temperature. Her knuckles brush your hand as you also reach for the dial. It’s barely anything, but still, you feel it everywhere.
“Oh—sorry,” she says automatically, but she doesn’t pull her hand away right away.
“It’s okay,” you manage.
Her fingers linger for half a second longer than necessary before retreating. Your pulse spikes. She glances at you, just briefly. “Still cold?”
“A little,” you admit.
Cassie hums thoughtfully, then, without comment, reaches for something in the back seat. “I knew I left this in here for a reason.” She drapes a blanket over your lap, and her hand brushes your thigh.
This time, she doesn’t apologize.
Her palm rests there for a moment—warm, steady—like she’s grounding you. Like she’s checking something. You freeze, breath shallow.
Cassie keeps her eyes on the road, voice calm. “Let me know if that’s not okay.”
“It’s okay,” you say quickly. Too quickly.
Her thumb presses once, gentle, just above your knee—an almost-question.
Then she pulls her hand back and settles it on the wheel again, as if nothing happened.
But everything has changed.
You swallow, then glance at her. “Can I tell you something?”
Cassie smiles slightly. “Usually when someone says that, it’s not good.”
You laugh, nerves easing just enough. “I overheard you earlier. In the hall.”
She raises an eyebrow. “About what?”
“With Dana,” you say. “You said—” You hesitate, then decide to be brave. “Please don’t hate me for this. I heard you say you needed to get laid.”
Cassie actually laughs, low and surprised. “How did you hear that?”
“I didn’t mean to, honestly. But I was looking for you to report my theories for the stroke patient, and I had just turned the corner,” you’re panicking again. “I stopped when I heard it, figuring that was more of a private moment.”
Cassie shakes her head, embarrassed but amused. “I guess it wasn’t as private a moment as I thought.” She glances at you, something unreadable in her expression. “So. Is this where you tell me I should watch what I say?”
You shrug. “I don’t know. I just thought it was…relatable.”
The car slows at a red light. Cassie stops, then turns toward you fully. “Oh really?” she says softly. Her hand lifts from the wheel and settles on your thigh again—deliberate this time. Grounding. Confident. “You wanna help me with that?”
Your breath stutters. “I-I-” you hesitate, looking at her facial expression for something like her pulling away. You don’t know what to say. You really don’t. It’s hard when she’s looking at you like that.
She studies your face carefully, thumb brushing a small, reassuring circle against your leg. “I’m kidding,” she says gently. Then, quieter, “Unless you’re not.” The light turns green, but she doesn’t move right away. “I just want you comfortable,” she adds. “Always.”
You nod, pulse still hammering. “I am.” That earns you a smile—slow, knowing. “I promise.”
“Even if you aren’t joking, baby, I’m too old for you.”
“I don’t think so,” you say simply, shrugging.
“I’m also your boss, technically.”
“Oh, for fucks sake, I don’t care.” You tell her.
She doesn’t remove her hand. She keeps driving, it’s about a 20-minute ride home from work, and it’s only been about 11 minutes so far that you’ve been in her car. She begins to slowly move her hand up, asking every time ‘Is this okay?’ and every time you nod your head.
“If we’re gonna do this, I need a verbal word, honey.”
“Yes, yes, it’s okay.” You look at her, but she’s not looking at you. She’s staring straight at the road. Which is fine because you’d rather not get into a car accident while finally hooking up with Doctor McKay.
Her fingers are now playing with the tie of your scrubs, and you help her, quickly unfastening the bow and looking at her hesitantly before she nods, and you’re pushing your scrubs further down. It’s hard to do all of it with the seat belt still on, but you make it work.
Good lord, this feels like a wet dream. This seriously cannot be happening. Trinity was right. This was not just a ride home. You just remember, however, that you hadn’t shaved your legs in a while, but McKay doesn’t seem like someone who’s bothered about hair like that.
You sit in the passenger seat now with just your shirt on and underwear. You swallow nervously. Her hand is now back on the steering wheel. But you’re not left wondering for long, as Cassie’s hand slips between the fabric of your underwear and skin, and travels over your mound, reaching the slick in your folds.
You gasp, your hand shooting out to hold the door handle.
“I haven’t even started yet.” She teases, and the words you wanted to say back feel like lead in your mouth. “Open your legs a bit more.”
It’s harder to do with the pants around your ankles, but you do it for her. She slowly begins to insert one finger, working you up for a second one. Your moans are quiet at first, you’re trying so hard not to beg her to look at you because you know she has to drive the car and get you to your destination point, but you want to so badly.
“Fuck, sweetheart.” She murmurs.
You are hyperventilating, you fear. You decide to help her, dragging your hand into your underwear and beginning to circle your clit. You let out a whine, your head falling back against the headrest.
You whimper for her, feeling her fingers move in and out of you. She’s doing it slow, teasing you, working up your body over time. You lean to your side, leaning slightly into her, and you turn your head to bury it against her arm.
She’s skilled with her hands, that’s for sure. She has to be. Being a doctor requires a lot of that. Her fingers soon find that sweet spot inside you, and it makes you roll your hips against her hand.
“I-I don’t know how this is helping you get laid.” You tell her, your free hand coming to clamp around her upper arm. Not hard, but just to hold something.
“It’s working, don’t worry.” Her voice is soft. “Just keep feeling good. Tell me if something doesn’t, okay?”
“Okay.” You nod, propping your leg up on the seat. You’re breathing rapidly. You don’t know if it’s the way her fingers are working or your dream becoming a reality, but you already feel yourself reaching your peak. Warmth spreads from your lower tummy to really all over your body.
Goosebumps appear on your skin. “C-Cassie, I’m gonna cum.” You warn her, and she shakes her head.
“No, you’re not.” Her lips are pressed tight together.
“What? Why not?” You’re breathless, you realize as she removes her fingers, as do you.
She points forward, and you look, realizing you’re at your apartment complex. You whine, feeling more than disappointed, but you pull up your scrub pants and re-tie the knot. But you get confused again as Cassie goes to the garage complex.
“What’s your password?” She asks, and you look at her with a frown before saying,
“281495. Why?”
“You’ll see.” She shortly replies. She pulls into the parking garage, picking a spot secluded from the other vehicles. There aren’t a lot of people that live in your building anyway, but everyone, for some reason, loves to park as close as possible to one another.
“What are you doing? You could’ve just dropped me off at the front, it’s not a big deal.” You smile at her.
“Oh, we’re not done, honey. Just because I said you weren’t gonna cum, doesn’t mean I meant at all.” She puts her seat back and motions for you to come sit on her lap, so you do just that, but she soon stops you before you can even get out of your own seat.
“What?” You ask with a little bit more annoyance than you intended. She raises an eyebrow, looking you up and down before you instantly apologize. “Sorry. I didn’t mean-”
She cuts you off. “Take your shoes off. And pants. Keep your underwear on.”
You do as she tells you and then join her in the driver’s seat. She doesn’t give you a chance to fucking breathe before she places her hands on your hips and makes you sit on her right thigh, making you groan at the feeling.
“Put your hand on my chest.” She lowers your left hand to rest on her sternum, and then your right hand comes to place itself, clamped down onto her shoulder.
“Can I move now?” You ask her genuinely, and she nods, her eyes coming to settle on where your cunt moves against her pants. You go ahead and begin to move up and down quite fast. She can’t stop herself from running up the backs of her thighs, loving the little whimpers and moans that leave your lips.
“Feel good?” She asks you, and she feels your nails bite into her skin as you nod at her words. “Shh, slow down, sweetheart, slow down.”
But you soon remember her rule when she stops you from moving completely. You nod at her, breathing out a ‘sorry’ as she lets you move again over her thigh, throwing your head back and basking in the feeling of it.
She coaxes you to open your mouth, her thumb prodding softly at your chin, because you realize you’ve bit down on your bottom lip hard enough to draw blood.
Your eyes open, and you lean forward a little, looking at her before dropping your head into the crook of her neck. You let out whine after whine and whimper after whimper. You can practically hear the smile that’s on her face right now.
“God, those sounds are amazing.” Cassie breathes out, rolling her hips in time with your own. It stimulates you more, making you whine and lurch forward closer to her, if that was even possible. “You’re doing so well. So good, honey. Just like that, there you go.” You feel her nudge her thigh in the apex of your thighs a few times, pressing against your clit as she does so, making you moan every time.
She does it continuously, hitting the same spot over and over again before you start to tremble above her.
“Cassie, oh god, fuck!” You moan out, pressing down hard onto her thigh. You pick yourself up off her, and you can feel your legs trembling on either side, so she doesn’t hesitate in jerking her leg up just a little bit, to meet your cunt hard, and it’s enough to make you let go. You were already worked up, of course, so it was just waiting to explode soon.
“Cassie- shit!” You moan loudly, your head dropping back down to her neck. She holds you close and runs her fingers over your back, soothing you as you shake on top of her.
“Shhh, it’s okay. You were so good.” She whispers in your ear, and you feel like you could cry. “Tell me when you’re ready to go.”
You mumble out an ‘okay’ before she resumes running her hands up and down your back. Trinity was right about something; Cassie loves to talk you through it and praise like crazy.
