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Her room on the TARDIS has always been Yaz's place. It's completely hers — no risk of Sonya walking in, no noisy neighbors, no annoying window angled just-so to let the rising sun hit her eyes while she's still sleeping. It's the one place in the universe that's truly safe and private for her. On some level, Yaz knew that the Doctor could probably come in any time she wanted, but it wasn't something that had ever come up.
Until now.
It's late. Or, at least, it's the arbitrary time in the 24-hour cycle Yaz functions on that she's designated for sleep, which means her brain thinks it's late. The lights are dimmed, the temperature is low enough to justify the fuzzy comforter she has pulled over her bare skin, and she's in the hazy mid-zone between waking and sleeping.
She almost doesn't notice her bedroom door opening. No light comes in, and the hinges don't creak. The only noticeable difference is a change in the smell of the air, a sudden burst of engine oil and black tea that Yaz associates with the Doctor. But it's different this time, richer and stronger.
"Doctor?" Yaz murmurs. "What're you…?"
The lights brighten just a bit, enough for her to see the Doctor's silhouette move closer to her bed. Something about the shape of it is off, and as Yaz's eyes adjust, she realizes that the Doctor isn't wearing her coat.
"Doctor," she tries again, louder. "What's going on? Did something happen?"
"'s nothing," the Doctor says. Her voice is low and a little rough. "Just need something from you."
She's standing at the side of Yaz's bed, now, and her scent is overwhelming. It almost reminds Yaz of when Izzy Flint had first presented as an Alpha and thought it was hilarious to corner Yaz in the halls and deliberately release pheromones, drowning out every other smell until Yaz wanted to be sick. But the Doctor doesn't even have a designation, Yaz is sure of it. She would have known by now.
Slowly, she sits up, bringing her comforter with her to cover her chest. "What do you need?"
The Doctor leans in, eyes glinting in the dim light, and brushes her nose against Yaz's neck, just below her mating gland. It sends an involuntary shiver down her spine, some deeply-buried Omega part of her brain perking up and paying attention. She almost flinches away, but forces herself to stay still. The Doctor will explain, and all of this will make sense soon enough.
"D'you have any idea how hard it is to hold back a rut in jail?" the Doctor breathes, the words ghosting against Yaz's skin. "No suppressants, no company, and for years."
"Doctor." Yaz's voice is shaky with something adjacent to fear. "I don't know what you're getting at, but I'm not- I don't-"
When the Doctor leans away, she's flooded with relief — until a hand takes the comforter and tugs it out of Yaz's death grip in a single motion, then tosses it carelessly aside, leaving her completely naked. The mattress dips as the Doctor moves one knee, then the other, kneeling over Yaz's tightly-clenched thighs.
"Sure you do," the Doctor says. She curls one hand into Yaz's hair and pulls gently, so that she has no choice but to meet those dark eyes. "Doubt you've ever had a proper heat, with all those suppressants you take, but you must've learned the basics."
Yaz still remembers that particular lesson in mortifying detail. It was some time in year eleven, after everyone had presented, and they'd been split up by designation. While the Alphas and Betas were off getting their own explanations, the Omegas got a lecture on how to avoid embarrassing themselves during heats. Never go into heat around an Alpha unless you're in a committed relationship, always wear protection, and be very, very careful about who you let mark you.
Strangely, they never covered what to do if your alien friend is suddenly straddling your naked body in your own bed, apparently intent on knotting you without much input on your end.
"If you need someone to-" Yaz chokes on the word before she even tries, but powers on. "There's got to be some place where you can… find someone. Because I really don't- you're my best friend, but I-"
The hand in her hair tightens, and Yaz finds herself being pulled forward into a messy kiss. She's too stunned to do anything but allow the Doctor to deepen the kiss, squeaking helplessly at the sudden presence of tongue.
While her brain is struggling to catch up with what's happening, Yaz feels two cool fingers press against her gland. Immediate, overwhelming pleasure floods through her, her thighs relaxing from their panic-induced tenseness.
"Good girl," the Doctor croons when she finally lets Yaz breathe. "See? Already wet for me. You'll be perfect."
She releases Yaz completely for a moment, tugging her shirt off and then beginning to undo her trousers. Another wave of the strong scent hits Yaz's nose, and her head swims. She's never been around an Alpha in full rut before, and with good reason — the pheromones can trigger a sympathetic heat in Omegas, even if they're on suppressants. One of nature's clever little tricks to help mates sync up with each other. Except the Doctor is not Yaz's mate, and she does not want to go into heat, especially not now.
"Doctor, please," she says desperately. "I don't want this, and you don't want to- to do this to me. It's just hormones. If you just let me up, we can figure something out."
The Doctor shakes her head. "I've already figured it out. You'll be a good girl for me and let me knot you until this passes, then we can forget all about it. I'll even let you pick where we go next, okay?"
Yaz wants to protest that no, it's very much not okay, and she's terrified and betrayed and one trip isn't going to fix that. Yaz wants to say a lot of things, at that point. Instead of any of it, though, she moans, because the Doctor leans in to suck at her gland. There's the faintest brush of teeth against the sensitive skin, but none of the sharp pain that would signal a marking bite.
Hot, unwanted pleasure pools in between her thighs, and Yaz squirms. The Doctor laughs and pulls back.
"I was right, wasn't I?" she grins. "You've never had a heat."
Mutely, not trusting herself not to moan again, Yaz nods.
"Think of it as a learning experience, then."
And with that, the Doctor takes off her knickers. They weren't doing much to hide the shape of her arousal, but at least before, Yaz had been distracted. Now, with the Doctor kneeling between her thighs and nowhere else to look, she can't avoid it. The Doctor's cock is hard, longer than Yaz wants to think she can take, and horribly thick.
Its head is brushing slightly against the inside of her thighs, cool against her skin. Worse, though, is the way her cunt clenches, dripping slick. She wants her thoughts to get fuzzy, or distant, or anything other than crystal clear and focused on how good it would feel inside. Yaz is very quickly giving up on getting what she wants, at the moment.
"There it is," the Doctor says, cupping Yaz's face with one hand and stroking her thumb over her cheekbone. "Your pupils just got nice and dilated, which means your heat just kicked in. Doesn't it feel good?"
It feels like her body is burning up from the inside, like she's going to die if she spends another minute empty. In no way is it good.
"It'll be even better once I'm inside you, don't worry."
The Doctor grabs each of Yaz's legs at the crook of her knees, then pushes them back and apart. The cold air that hits her dripping cunt makes her gasp.
Then, with very little warning, the Doctor takes hold of her hips, and guides her cock inside. She isn't slow about it, which comes as something of a relief. The worst of the burning stretch is over relatively quickly, but it just keeps going, deeper and deeper until the Doctor finally bottoms out inside of her.
It's wonderful. Yaz doesn't think she's ever felt so full or so good before in her life. An orgasm crashes over her so hard that her vision whites out for a moment, and she doesn't process the keening sound filling the room as coming from herself for a good fifteen seconds.
The Doctor smiles, all teeth and lust. "Told you. You're such a good girl, Yaz."
Yaz whimpers, the words hooking onto some hungry part of her brain and pulling. She wants to keep being a good girl for her Alpha, more than she's ever wanted anything in the world.
"Now, I'm going to knot you-"
Yaz squirms, imagining how the thick press of the knot will feel inside of her.
"-and then you can tell me if you want it again, okay?" The Doctor's hands tighten on her hips. "If you've had enough, I'll leave."
She doesn't give Yaz time to respond — not that she could have managed anything coherent — before pulling most of the way out and then slamming her cock back inside. It makes the most obscene noise, wet and sloppy, but Yaz couldn't care less, moaning shamelessly at the pleasure.
After a few more shallow thrusts, Yaz feels something warm coat her insides. Then, far faster than she thought it would, the Doctor's knot swells, plugging the come securely in place. Yaz comes again with a shudder, clenching down around the new thickness.
"So, so good," the Doctor says softly, resting her head against Yaz's shoulder. "Only your first heat, and you're taking it so well. You ought to be proud of yourself."
And, because her Alpha orders it, Yaz is. She's taken her Alpha's knot and the come still sporadically spurting into her, and her Alpha is pleased, and so she is proud of herself.
Gentle, so gentle that Yaz doesn't register it at first, the Doctor moves to rest her teeth over her gland. The pressure sets Yaz off on another orgasm before she realizes what's going on.
"Could mark you," the Doctor murmurs. Her tongue flicks out, cool and wet against flushed skin. "Would you like that?"
Most of Yaz's knot-dumb brain answers with a resounding yes please, but the words also send a shock of fear through her, pulling back the mask of pleasure that she's been forced to wear. If the Doctor marks her, that's it. There's no way to undo that, no override button — for the rest of her life, her brain will be altered to want the Doctor every time she slips into a heat. Her scent will change, and noticeably. It won't be something she'll be able to hide.
"Don't," she gasps, barely more than a whimper. "Doctor, don't."
The Doctor hums quietly. "Maybe you'll change your mind."
Her hips move, and the way her knot tugs against Yaz's walls makes both of them groan. Another load of come pours into her, settling warm and heavy, and the Doctor kisses her. This time, Yaz parts her lips of her own accord, letting the Doctor dig her teeth into the thin skin until it hurts. It's easier to give her what she wants than it is to struggle, and it makes the part of Yaz hardwired to be bred so happy. She could almost believe she wants this.
"You're absolutely perfect," the Doctor praises, her mouth still against Yaz's. "So tight and wet, and you're being so obedient for me. Think my knot's nearly down, too. We can try something a little different next."
True to her words, Yaz can feel the Doctor's knot loosening its pressure on her walls and the slow, wet slide of come leaking down her cunt. When the Doctor presses another kiss to her mouth and pulls all the way out, she's convinced for a moment that she's bleeding — the sudden rush of liquid flowing out, spilling onto her sheets, is utterly alien to her.
"Roll over," the Doctor orders, tapping Yaz on the side of her ribs. "Hands and knees."
Yaz blinks up at the Time Lord, a vague memory flitting through her brain. "Y'said I could stop if I'd had enough."
"You haven't." Waving one hand dismissively, the Doctor reaches down with her other to slide three fingers into Yaz's mess of a cunt. She probes around inside for a moment, seemingly oblivious to the thick warmth of her own seed, until she presses just-so against somewhere that makes Yaz cry out and see stars. It's not quite an orgasm, but she clenches down and shudders all the same. "See? You've got at least another round left in you."
The Doctor slips her fingers back out, wipes them on the sheets, and then when Yaz — still more than a little hazy on what's happening — fails to roll over as instructed, flips her onto her stomach. Any protests Yaz might have been able to make are muffled by her pillow as the Doctor grabs her hips from behind and tugs her onto her hands and knees. Like this, she feels even more exposed, even more vulnerable, and, horribly, even more wet. She wants to be a good Omega, she wants to be knotted and filled and bred, and something about this position makes all those instincts overpowering.
A cool weight blankets her back as the Doctor kneels behind her and leans forward. Just like before, she doesn't bother with any sort of preparation or warning before plunging into Yaz. The new angle of this position makes her cock hit against that same place she'd pressed at with her fingers, each and every time she thrusts in or out. Yaz comes once with a strangled whimper, then a second and third time as the Doctor reaches down to press at her clit. There's no finesse to her movements, just unrelenting sensation, and it makes Yaz's head spin even more than the blend of Omega instincts, fear, and heat-induced arousal already has.
After wringing a fourth orgasm out of Yaz, the Doctor slows her thrusts for a moment. There's no gush of come, no swell of a knot, and Yaz doesn't understand.
"Elbows," the Doctor pants. "And lift your hips more."
She's obeying before she even has time to think, dropping onto her forearms and trying to raise her arse as much as she can. The Doctor's weight shifts, and then she begins fucking into Yaz again, harder and faster and impossibly deeper. Distantly, Yaz realizes that she's being mounted, and the thought makes her moan.
The next time the Doctor stops, it's to come inside of Yaz again, knot ballooning to press against her slick walls, forcing another her into yet another orgasm. Yaz's knees hurt and her back is growing stiff, but she can't so much as breathe without some part of the Doctor's cock rubbing against something unbelievably sensitive. All she can think of is the thick, heavy press of it inside of her and the warmth of the come slowly making her cunt stretch. There's nowhere else for it to go, after all.
"Now," the Doctor says, breathing hard, "do you want me to mark you?"
Yaz can't form a reply to the question. She barely even processes that the Doctor's spoken.
A hand squeezes her breast, short nails digging into the tender flesh until she squeaks. "Yaz. Do you want a reward for being such a good girl?"
That, her knot-dumb brain can figure out. Her Alpha is offering her something for being a good Omega. Yaz nods eagerly.
"I knew you'd change your mind," the Doctor smiles. "Knew I made the right choice, picking you. Knew you'd-" Her hips jerk forward again, and Yaz keens as more come spurts into her. "-be so pretty taking my knot."
And then, just as she'd promised, the Doctor leans down and sucks on Yaz's gland. It's only for a moment, but she nearly passes out from the delicious overlap of her Alpha's knot inside of her and her Alpha's teeth on such sensitive skin. When the sensation switches from suckling warmth to sharp pain, Yaz can't do anything but jolt underneath the Doctor's weight, which in turn makes the Doctor's cock press against her perfectly. Under a flood of unbearable pleasure, Yaz's vision goes dark.
When she wakes, Yaz feels hands on her hips and something hard and long moving inside of her. Her head is cluttered with a mess of more and Alpha and Doctor, Doctor, Doctor so dense that she can barely think. Fighting for prominence is the memory of teeth sinking into her gland, the Doctor's scent filling her nose, the Doctor's hand on her breast.
She opens her eyes to see the very person in question, fucking her as though she's never passed out. Words are too difficult to manage, but she moans when the head of the Doctor's cock hits something tender inside of her.
"Feel better after your nap?" the Doctor asks, not even pausing in her slow, deep thrusts. "Your brain needed to recalibrate, that's all. It's a lot of work, being marked. Or so I've heard. All those fidgety little synapses are so delicate. Gotta make sure none of the wires get crossed."
Almost as an afterthought, the Doctor stills and comes, her knot quick to follow. Yaz doesn't have it in her to come again, not with how wrung out she feels, but the filling warmth is utter bliss.
"And now you'll be a good girl for me whenever I need you," the Doctor promises. The praising, soothing tone of her voice alone makes Yaz want to melt with happiness. "We'll never have to go through all that messy business that we did earlier. I'll just knot you up, and you'll take it so, so well."
The Doctor leans down to kiss her, and Yaz smiles.