“Everything is under control.” Thankfully, it’s a lot easier to lie through the phone. Your parents deserve a real vacation, and the situation hasn't gotten so far out of control that you’d force them to cut their trip early. If that would even be possible on a cruise in the middle of the ocean. “I’m handling it fine. She’s been in bed for most of the day. I’ll see you when—” Your phone screams against your ear and you curse, dropping it as an alarm blares, cutting off as soon as it hits the floor.

You pick up your phone and see the screen has gone black. Fruitlessly, you hammer the power button, trying to get it working again, but nothing happens. Fuck. Just what you needed. Your sister still had her phone, but like hell you were going to be able to use that. And with her condition as it was, you weren’t going to be able to leave the house for long periods—not to mention that you didn’t actually have the money on hand to buy a replacement.

Okay, breathe. You could make it a few days without a phone—worst case, you could email your dad. There was enough food in the house, and you could probably scrounge up enough cash for a pizza or something. What else? A banging noise comes from upstairs, and you shake your head, snapping yourself out of your funk. Right. Your sister was depending on you, after all.

A gentle knock on her door and the banging on the wall stopped, thankfully. You shift the plate of food in your hand, preparing to open the door, before something impacts it—something soft, like a pillow.

“Go awayyy,” comes a groaning voice. Honestly, you’d really like to. Everything going on right now was awkward at best and mortifyingly embarrassing at worst, but somebody had to make sure nothing happened to her, and you were the only person on staff.

“I brought food,” you say instead. “I’ll leave it out here for you.” The embarrassment wasn’t one-sided, to be fair. You’d never really understood a lot of issues your sister had. The biggest part of it was the difference in your gender, of course, but there was also the fact that the two of you shared very few interests—besides occasionally watching the same TV shows, the pair of you rarely talked at all lately, which was terribly sad.

“Look, my phone broke earlier. Can you text dad and tell him that?” you ask. An affirmative noise comes from behind the door, but not much else. “And, hey. I know it’s really… you know, with all this stuff. But if you need something, you can ask me, alright?”

That gets no response. About as expected. With a sigh, you set the plate down, and turn away, eyeing the tightly closed door as you walk back down to the kitchen. As you head down the stairs, though, the door opens, a hand sneaking out to grab the bowl of baked ziti.

-~=~-

Hakos Baelz has a problem. Well, she has about three dozen problems, all of varying intensity, but one rose to the forefront at the moment. There were two parts to it—an empty bottle of pills, and a burning heat that shot straight from her groin up her spine to boil her brain in her skull.

Heat suppressants were popular for a good reason—mating seasons may be good for animals, but for people it was an awful inconvenience to be forced to drop everything for three weeks and think of nothing other than getting pregnant and furious, harcore breeding that—

She shook off the thought pattern before it could go any further, though it took real effort to steady her breathing. Through gritted teeth, she picked up and threw the empty bottle at the wall, her other hand clutching her stomach to try and soothe some of the burning sensation away.

The worst part of all of it, though, was her brother. And she knew it wasn’t fair to think that, but that didn’t stop it. He walked around the house just reeking of vir—No! No, that wasn’t it. The thing she hated was his constant attempts to help. Leaving her alone was the only real help he could give—and having him constantly around the house basically confined her to her own room and the corridor that led to the bathroom, since her stupid rat brain kept telling her to jump on any man she saw, including him.

Again, she centered herself. It didn’t matter. She was in charge, not the parts of her that wanted her to spend the next three months caressing a growing bump in her belly with maternal joy as proof of their love, as she bloomed from maiden to mother and—she stopped her hand as it creeped down below her waistline. Focus.

-~=~-

The banging on the walls happened a lot more often now. It wasn’t the same as before—not like your sister was just pounding on the wall in anger or frustration, but like she was moving furniture or thrashing around in bed for hours on end. You tried to ignore it—you’d given her run of the whole second floor now, spending your nights on the couch in a spare flat sheet, only venturing up when you had to get new clothes and toss old ones into the hamper—but it didn’t seem to have helped much.

One of the few things your mother had been adamant about on finding out about the situation was that you couldn’t let Bae outside—and you knew why, having heard the stories passed around on message boards about kemono girls(and the occasional boy) tackling somebody in the street and assaulting them in the madness of heat. So you paid attention to the doors, but you weren’t really worried about that. Bae was a lot smarter than your parents gave her credit for, and she wouldn’t let some dumb ‘mating season’ conquer her.

Which is why you’re surprised when you hear bare feet padding down the stairs. It startles you away from the TV—thank god for streaming, the only thing keeping you awake since your phone broke the other day. Your sister stands halfway down the stairs—frozen like a deer in the headlights.

She looks half-feral—her hair is wild, sticking up at odd angles, bangs hanging down over her eyes, her ears flat against her head, barely visible in the tangle. Her clothes are little better. A shirt hangs on her frame, clearly at least one size too big, the buttons mismatched… wait a second. That was one of your shirts. The one you were wearing yesterday.

“Hey…” You wave, a bit uncertain. Was it… over? You really couldn’t tell. It was supposed to take like, a week, right? “Do you… need something?” Her eyes looked a little unfocused, and her cheeks were flushed, her body swaying somewhat as she held the bannister. Was she running a fever? You move to get up from the couch to check on her, and she moves faster than you’ve ever seen her move before.

Before you can really take in what’s happening, you’re pinned against the couch, your sister on top of you. Somehow, despite not even being 150 cm, she towers over you in that moment, a light in her gaze that makes it seem like she’s about to bend down and rip your throat out with her teeth. You’re the one who’s frozen now, too paralyzed to even ask her what’s going on.

And she does bend down, but instead of sinking her teeth into you, she takes a deep sniff. You nearly break out laughing, sure that this is one of her pranks, but the way she’s acting is too real for that. You can feel heat coming off of her, and there’s a strange smell that fills your nostrils as you shift, trying not to notice that she’s clearly not wearing underwear, just a pair of very thin shorts and your shirt, which was big enough to slip off of one shoulder as she desperately clung to you.

“Bae?” Your voice comes out in a whisper, almost frightened. Her eyes wander over you, resisting any attempt to hold your gaze. “Are you okay?” Again, she doesn’t respond. “I can call someone if—mmph!” You’re cut off by her lips mashing into yours, alarm spiking as you attempt to fight her off, but she’s a lot stronger than you expected and she has the leverage, so despite your size and weight advantage, she keeps you down for long enough to force her tongue between your lips, slipping between your teeth before you can even fully close your mouth, drinking your saliva like it’s the water of life.

It’s not long before you force her off of you, maybe with a little bit more power than is strictly required—you’re in panic at this point, and she’s dug in with her nails to the point that tears are left in your skin as you toss her off, stinging in the open air and making you gasp for breath, filling your lungs with the strange scent that surrounds her.

“What the fuck!” You nearly scream as Bae recovers, rolling her shoulder as she rises, swaying on her feet as her thighs rub together. A button on your shirt strains as her chest heaves, unrestrained by—what the fuck were you thinking? Your sister had clearly gone crazy from fever or something. “Shit, I… I’m sorry. I shouldn’t have done that. Are you alright?”

You’re expecting a lot of responses. Another feral leap, a curse-filled rant about you taking a prank too far, even a sudden snap back to her senses with a reveal that she’d been sleepwalking all along. What you’re not expecting, however, is for her to start crying.

“You don’t… sniff, you don’t like me?” She blinks through teary eyes, and you’re left utterly baffled by her logic, or lack thereof. “I jus… I just wanna…” Any further words are lost in sobs as her face falls, wiping at her eyes with balled fists.

“…what?” Shit. You were being insensitive again, weren’t you? You loved your sister, you really did, but… you were pretty sure that trying to make out with your brother wasn’t a way to express that. “I don’t get it.”

She says nothing, and you tentatively step over to her, wary of another… whatever just happened. You have absolutely no idea what to do here. So you just go with what feels right. You wrap your arms around your sister, pulling her against you, leaving trails of wet behind as she rubs her face into your chest, a hand running through her hair, catching in tangles almost immediately as your thumb rubs the back of her ear.

“Look.” You’re still not sure what’s going on, but that’s clearly your fault. “I’m sorry,” you tell her, having no idea what you’re apologizing for. You lean down, whispering. “I don’t know what you’re going through.” You don’t really know as much about her as you thought you did, you’ve learned. “But I want to help.” She sniffles again, probably rubbing snot all over your shirt, and you pull her away, meeting her gaze so she knows you’re serious. “So if there’s anything I can do. Tell me.”

Bae blinks, eyes rimmed with red, and finally they seem to fully focus on you. She takes a deep breath, and then she breaks out of your grasp, sprinting back up the stairs. Again, you’re left with no idea what’s happening. A finger rubs your lips idly—what the hell was up with her kissing you? She’d jokingly flirted with you in front of your friends before, but never gone that far, and especially not alone. And what was that smell? It was spicy and yet almost sweet, an enticing aroma that made you want to take big lungfuls of it—some perfume? But why would she be wearing perfume at a time like this?

If only you still had your phone, you could at least try to look up some of the answers. Instead, you’re stuck with whatever terrible explanations you can come up with on your own. You got into uni for football, not chemistry for god’s sake. How were you supposed to know any of this stuff?  The stories had mentioned spikes in libido, but surely that wasn’t enough for her to go after her own brother, right?

Well, you think, maybe knowing this stuff would be easier if you paid any attention to her in the last five years. The thought depressed you even further, but it was a deserved reprimand for the way you’d been acting. Even if she didn’t want to hang out with you anymore the way the two of you did when you were little, it took both of you ignoring each other to create a situation like this, where she didn’t even think she could tell you what she was going through.

There had to be something you could do to bridge this gap. You collapse onto the couch, racking your brain for anything she’d mentioned recently, anything you could use…

-~=~-

The door slams behind her as she scrambles into her room, her heart racing at a mile a minute. She knew being in heat made you dumb, but not ‘make out with your brother and then cry about it’ stupid! Her hand runs over her stomach, a finger jabbing at her stupid ovaries. That’s what got her into this mess. Her womb burned, achingly unfilled, and she sucked in a breath, trying desperately to control herself.

She sits on the bed, melancholy outweighing the burning need between her legs, at least temporarily. This sucked. And it only got worse every time he came knocking on the door trying to offer her coffee or food, as if it would suddenly bring things back to the way they used to be. He had no idea how heat even worked, probably—he just thought it was like a cold she could get over. Well, maybe in a couple ways they were similar, but it was vastly different, and every time he got close her body ached for him, and he kept pushing, and every time he did the need got stronger.

Maybe her idiot instincts had the right of it, at least a little. She did want to be close to him, even if not in that way. They used to be close, didn’t they? And then they just… fell apart. How had it even happened? Was it when she decided to start taking dance classes? When their friend groups diverged? Maybe even before that?

For some reason, tears are welling up in her eyes again. Hormones, probably, but that didn’t make the feeling behind them less real. She clicked her tongue, wiping her eyes, and then dove face-first into a pillow. Her tail lashed back and forth, and her mind wouldn’t stop moving. As suffocating heat crept up her abdomen, a hand snaked below her waist again, and she shifted on the bed to bring a pair of her brother’s shorts close. Fuck, she wanted him. No, she needed him.

-~=~-

You stand at your sister’s door, honestly a little nervous. The sound of springs rattling and something bumping against a wall do trouble you, but the important part was the looming specter of an actual conversation—and sure, right now is hardly a good time for it, but you’ve put this off for long enough.

“Hey.” You knock on the door, and the noises briefly stop, but you get no response. “Are you in there? I went shopping and I picked up something, figured you might like it.” Again, she doesn’t answer, but you hear a low groan. Maybe she’d been rolling around in bed? Heck, maybe she’d fallen out of bed and knocked herself on the head. “I’m coming in,” you warn, and open the door.

Her room is a mess, as always—though then again, the last time you saw inside her room was months ago. Clothes are piled on the floor, and you spot several articles of your clothing mixed in—she certainly hadn’t been doing much laundry, but you hadn’t known it’d gotten bad enough for her to need to snatch your clothes. Bae lies on her bed, the sheets tangled as she—oh. Oh god.

“Hff, nnhh!” she moans, her mouth muffled by a pair of your underwear held over her nose, her fingers thrusting inside her panties with a furious frequency usually reserved for extremely difficult rhythm games. “Oh fuck, fuck me!~” Her voice is low and husky, and her bedframe bangs against the wall as she rides her fingers, eyes half-lidded and unfocused.

You drop the container of fresh strawberries, and she finally notices you, jumping up as her tail sticks straight up, startled. Your shirt, which she’s still wearing, opens as she does so, giving you a view of her chest and stomach, and you quickly avert your gaze, flushing. That strange perfume is in the air again, even more concentrated than it was yesterday. You blink, completely unsure where to look, and wind up staring at a poster on the wall of a band you don’t recognize. Some girls’ group, it looks like.

“I’m sorry, I didn’t know you were… uh, doing… that,” you babble, not meeting her gaze as you attempt to back out of the room, only to run into the door behind you, having swung closed on its own. “I’ll, uh, come back later?”

On a theoretical level, you were aware that your sister probably had masturbated before. God knew you had, when you were her age—which was only a year and a half ago, come to think of it—but you’d never expected you’d be slapped in the face with it. And masturbating while sniffing your underwear? What the hell was going on here?

While you can only really see the top of her head, you can hear your sister panting for breath, and though you’d love to turn and leave, for some reason you feel like if you turn her back to her, she’d tackle you again. You’re trapped.

No. You’ve been reacting instead of acting this whole time, and it’s done nothing for you. You had to take control of this situation, or at least make the attempt.

“Hey.” You snap your fingers, feeling like an asshole for it, but needing her to pay attention. “Talk to me here. What’s going on?”

A rough sigh, and the sound of springs shifting, but you’re not immediately struck by a thrown pillow or rammed into by an overzealous little sister, so that’s probably a good sign, right? You lean down, unintentionally catching another eyeful of her chest as you pick up the plastic container of strawberries. Thankfully, it hadn’t burst open—there were a few bruises on them, but they were still good.

“I d-dunno what you want,” she stammers, wiping her fingers off on your fucking shirt dammit you have to wash that. While she’s talking at least, you resolve to meet her gaze, and keep your eyes from wandering around her nakedness, though it’s a lot harder than you’d think given that she’s your sister. The air is heavy with her perfume, and your face feels flush, not entirely from embarrassment.

“I want to understand what’s happening,” you sigh, rubbing your forehead. It felt like you’ve been repeating that for days. “Just… I don’t even know what to ask. I know you’re going through something rough. How can I help?”

“You wanna help?” She swallows hard, biting her lower lip. With how sharp her teeth are, that’s gotta hurt. “Take your pants off.” You blink. Turn the words over in your head for a while. No, there’s really no hidden meaning there, it’s quite direct.

“…alright. Sure.” If it helped her, fine. Out of the corner of your eye, you think you almost catch her salivating as you remove your jeans, shimmying out of the pants—they were pretty tight on your calves, to be honest. You’re nearly matching, you suppose—if only she’d put the shirt on instead of leaving it open to tempt you like that—wait, what was that? The thought is gone as quickly as it appeared, leaving nothing but confusion in its wake.

“Ohh…” She rises from the bed, padding closer as her gaze fixes on your crotch. “Knew you were hiding something from me,” she mumbles, running her fingers along her lips, which looked strangely chapped, with bits of swollenness in the pattern of her teeth, like she’d been chewing on it.

There was a pit opening in your stomach. You pretty much understood what she wanted from you by now, but… besides the growing dread, you can’t seem to muster the disgust you expected to feel. Instead, smoldering embers of lust stir within your chest, your sister’s presence a poker stirring up a fire long gone cold—you hadn’t had a girlfriend in quite a while.

She presses against you, wrapping a leg around your back to keep you from moving as she plants her face in your chest and her nostrils flare, drinking in your scent. You softly pet the top of her head, though the expression of sibling affection is rather tainted by the growing lust twisting your relationship before your eyes. A part of you whispers that maybe this isn’t so bad, if it means the two of you will get to be close again—even if it isn’t in the way you wanted.

“I want you so much.” Her voice is a whimper, quieted even further by her mumbling into your shirt. “Ugh!” A huff, and you scratch behind her ears to try and calm her down. “I need you. I need it!~” she whines, humping your leg.

“It’s alright.” you whisper back, even knowing that it’s not, that all this is going to do is make everything a dozen times more complicated and worse for the both of you. “I’m here for you.” With a hand, you pull her chin up,and her lips pucker expectantly as you lean down to meet her in a kiss.

You’re not going to exaggerate. It’s no grand expression of love, no beautiful fairy tale moment. But there, in your sister’s half-trashed bedroom, both of your minds fogged by heat and pheromones, it’s exactly what’s needed to ignite the tension in the air, in the relationship between you, a rope frayed by years of divergence, into sensual passion.

Even in the depths of her heat, or perhaps because of it, Bae is surprisingly hesitant. Its on you to take the first move, to lift her into your arms with surprisingly little effort—she’s even lighter than she looks—and carry her the few paces over to the bed, laying her down as gently as you’re able.

She leans up to kiss you again, a chaste meeting of lips that’s entirely at odds with her furious masturbation or even the rough tongue-wrestling she’d pinned you with the other day. Behind the hesitation, of course, is uncertainty—she’s just as scared of what going through with this will do to your relationship as you are, but she can’t hold herself back any longer. So her tongue slips into the kiss, and she grabs your hand, interlocking your fingers as she tries to pull you down on top of her.

You follow along, perhaps thanks to your own uncertainty—neither of you wants to be the one to cross that final barrier, you realize as she pulls at the hem of your shirt, the tips of her fingers running along your abs with barely-disguised delight, a primal piece of her clearly thrilling at the idea of having a powerful male, her eyes wide, drinking in the sight of your bare skin as if she’d spent the last week in the middle of the Sahara.

Your free hand touches her shoulder, still surprised at the heat coming off of her body. She’s barely even sweating, which is even stranger. You’re not so lucky, sweat already beading on your forehead from a mixture of anticipation and your melding body heat. Another kiss takes your mind off of it for now, focusing on exploring each other’s mouths and bodies for a time.

She guides your hands to her chest, biting your lip with shark like teeth as you palm her soft breasts. You find a pair of rose-red nubs between your fingers, small noises welling from her throat as you softly pinch them, her hips bucking against yours.

Two layers of cloth are all that separates the pair of you from crossing an irreversible threshold, or however that saying goes—her panties are soaked, wet against your cock as it strains against your boxers, fighting valiantly to pierce your sister’s body and stop the leaking fluids.

“Fuck,” you grunt. Shit. Maybe this whole thing was wrong. Maybe you were making a huge mistake. But you’re not sure that you care anymore. “I—mmn.” SHe silences your doubts with a deep kiss, her tail wrapping around your thigh possessively, as if to keep you from rethinking your decisions.

A pure, unfiltered need emanates from every pore of Bae’s body, and you might be admittedly a pretty mediocre older brother at best, but keeping her waiting any longer would make you even worse.         So you withdraw your hands from her breasts, which makes her let out a sad squeak, and hastily pull down your boxers. She moans as you pull her panties aside, the sheer taboo inciting even more arousal, thick strings of sticky wetness left behind on your fingers.

Your cock pulses hot against her stomach, her lower belly burning even hotter than the rest of her as her womb convulses in anticipation, her thighs twitching and her tail scratching against your leg as her arms wrap around your back and force you down with a strength you’ve never seen from her. The message is clear enough even for you.

Pulling away far enough to align your tip with her entrance is difficult, your sister jealously guarding every inch of space between you, unwilling to let even a single iota of cool air in. Love and furious lust build a bonfire of your bodies, and finally, achingly slowly, you enter her.

You can tell by her nails digging into your back and her legs spasming, that she’s trying as hard as she can not to cum right away, whether out of some misplaced desire to not appear weak or lame for it, or simply out of sheer stubbornness. Surprisingly, you’re not far behind, the heady aroma of her scent mixing with the anticipation to put you on a very light trigger, desperate to thrust as deeply as you can, digging out her unexplored depths.

However, it is your duty as the older sibling to ease her into things like this, so as much as you want to slam your hips into her and pound her into the mattress, you don’t. At least, not right away. While she grips you close, her teeth biting into your shoulder for support, you ease deeper, her walls parting surprisingly easily. Well, maybe a week of near constant masturbation had prepared her a bit, which was probably a good thing.

With some effort, you manage to hold yourself back long enough to bottom out inside her, your tip pressing up against something hard, a barrier far deeper than the one you expected to feel. Glancing down, you can see a small swell in her abdomen, confirming that suspicion. Well, Bae was an active girl…

Stinging pain brings you back to earth as she pulls away a bit, fresh air hitting the teeth marks in your shoulder, her nails raking across your back. With your height difference, it’s hard for her to actually wrap her legs around you, but she certainly tries, still desperate to feel even more connected.

“I…” You trail off, unsure what you actually wanted to say. Your heart pounds in your chest, your pulse thundering in your ears as Bae leans up to kiss you again, but you pull away, sure that whatever it was would’ve been important. “I love you.” Oh. That’s what it was.

Beneath you, Bae blinks, stunned. You’re not sure why you said it either, honestly. But it felt like the right thing to say, and it’s not like you regret it. If anything, the way her cheeks flush as scarlet as her hair is adorable. Maybe you should say it again.

“I love you,” you whisper into her ear, and she squeaks at the sensation of your breath, your lips curling into an easy smile. “I’m gonna start moving now, alright?” She nods eagerly, and your hips slowly pull apart.

You start out gentle, but you’re beginning to get tired of taking your time, so you pick up the pace, setting a smooth rhythm that fills the air with the sound of flesh on flesh, perhaps battering her a bit harshly for her first time, but she doesn’t seem to entirely mind. She nuzzles against your neck, letting out small gasps every time you hilt inside her, her ears flicking back not unlike a cat’s. You pull her tight to you, not wanting to let her go for even a moment as desire mixes with affection. The feeling of holding her so close is almost enough to push you over the edge. Fuck. You really did love her, didn’t you?

“Shit,” you huff, tightening your thigh muscles to try and stave it back. Your sister is definitely feeling it as well, her eyes heavily lidded as she pants, her breath ragged as each thrust seems to force air from her lungs. You didn’t want to cum before her—going soft before she could get off would be probably one of the worst ways to end her first time. Gritting your teeth, you redouble your efforts.

Finding her sensitive spots is hard—given how inexperienced she is, she gives heavy reactions to just about every move you make, her breasts squished against your chest as you slam into her depths, scraping against her walls in an attempt to push her to further heights of pleasure. God damn it. If she wasn’t so adorable, you wouldn’t be having this problem. Really, the issue was just that your little sister was too damn cute.

Fuck it. You pull out completely, hearing her whine at the sudden emptiness inside her, and grab her thighs, hefting them up to reach even deeper. Her moans meld into a scream of pleasure as you slam back in, jackhammering her into the mattress. Nails dig into your shoulders in an attempt to anchor herself, her walls spasming around your cock as she cums.

While inexperienced, her makeshift massaging of your member is enough to push you into orgasm as well, letting a stream of curses fall from your lips as you slam one final thrust into her depths, seating yourself as deeply as you can, the juices flowing from the place where you’re joined staining white as you release your load inside her, grabbing her chin to force her into another deep kiss as you ride out your shared orgasm.

The waves of pleasure don’t last forever, however, and as you come down a bit more sobriety creeps into your mind. Not enough to really reflect on what consequences will come from busting a load into your sister’s womb, but enough to realize that you’d gotten a bit selfish there, forcing her into a mating press like that.

“Are, huff, are you alright?” you ask, eyeing her sweat-soaked body, her hair messily plastered to her forehead. “I can get you some water.” Half the reason you were doing so well was because of how well you kept in shape, and while Bae did a lot of dancing, she definitely didn’t have your stamina.

“I’m fine,” she huffs, rolling her eyes. She at least sounded a lot more coherent than she had earlier, which was nice. “But, uh…” She bit her lower lip, shifting beneath you. “Can we go again? There’s a bunch of other stuff I wanna try.” The look she gives you, curiosity mixed with arousal and a healthy dose of affection, is enough to get your flagging erection back to full mast.

“Maybe in a minute.” Despite that, you don’t want to get back to it right away. “Hydration is important, Bae.” She rolls her eyes at you again, but allows you to pull out, though not without one final hug, resting her head in the crook of your neck for a moment with a satisfied smile. Somehow, you get the feeling that there will be precious little clothing on your bodies for the next few days.