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Kara’s first heat hits her full force exactly two months after she lands on Earth.
It’s so stupid. She’s so caught up in everything else: all the novelty of it, of living with humans, of starting school, of having a sister, that she doesn’t notice the warning signs until it’s too late.
She’s making them late for school. Alex is outside the bathroom, pounding incessantly. She’s yelling something, but Kara’s senses are all dialed up to eleven, which somehow makes it harder to string Alex’s words together into anything sensical.
Kara’s sitting on the edge of the toilet, simultaneously shivering and sweating. One hand is shoved between her legs, trying to assuage the insistent ache there, but Kara knows deep down that that won’t be enough. She needs an alpha. And by the smell of it, Alex is one. Her sister is an alpha. Her only friend on this planet, and this could ruin it all.
Kara wishes she could bring herself to care.
She doesn’t last much longer before she unlocks the door. Alex practically falls through it.
“Finally. Jesus, what were you doing in here?”
Alex starts to ask something else, but all of a sudden, her nostrils flare and her demeanor changes. Her eyes are suddenly dark enough to fall into.
“Shit, Kara, you’re…” Alex says, her voice half an octave lower. “You can’t go to school like this.”
Kara wholeheartedly agrees. She nods, stumbling forward gracelessly into Alex. She doesn’t know what she wants, and she has no hope of vocalizing it. She just knows she needs her older sister to take care of her.
Ever since Alex entered the bathroom, her scent has intensified, mutating into something far sharper and more primal. It sends throbbing waves of arousal through Kara, and it’s all she can do to keep herself from flat out begging for Alex.
Fortunately, it seems that she doesn’t have to. Alex slaps a hand over her mouth and reopens the bathroom door, peeking out to peer over the balcony.
“Mom and dad are gone,” Alex declares, opening the door the rest of the way and tugging Kara by the wrist into the bedroom they share. As soon as the door closes behind them, Alex is pressing Kara up against a wall, leaning in so close that Kara can feel the puff of her breaths against her lips.
Everything is happening awfully fast. Kara’s heart races as she waits for Alex’s lips to touch hers, but Alex doesn’t get closer just yet.
“Kara…” she says, her voice strangled. “I can’t—I mean, you’re just a kid still, so why—?”
Kara wants Alex to stop talking and put her mouth to better use, but the sliver of her that still can form coherent thoughts attempts to answer Alex’s question.
“Stress-induced,” she mutters, because that’s her best guess. She’s been trying to put on a brave face, but it’s not exactly easy to lose your entire family and home planet and be shuttled off through space to a new family in a galaxy unfamiliar to you. The only thing that had kept her hanging onto the last shreds of her sanity was Alex’s presence, but now she was starting to realize that perhaps she’d latched onto Alex a little too hard.
She hadn’t known this would happen, though. She hadn’t even thought humans possessed the same kind of physiology as Kryptonians until she’d smelled Alex outside the bathroom door, her alpha pheromones no doubt activated by the sweet scent of Kara’s heat. It wasn’t something she could’ve just asked Jeremiah or Elizabeth or even Alex, either—she would’ve been much too embarrassed. She’d figured she was still a few years off from having to deal with having heats.
How wrong she’d been.
Alex presses in closer, crooking her neck so she can shove her face into Kara’s neck and inhale deeply. She stays there for a few moments before she speaks again, her voice low and sluggish, devoid of conviction.
“Dad has some heat suppressants in the other bathroom.”
Kara has never heard of such a thing—why would you want to suppress this?—but it doesn’t matter either way. She’s way too far gone for anything of the sort to have an effect, and by the smell of it, Alex is too.
“No—I need you, Alex,” Kara whimpers. Alex growls, low in her throat, and manhandles Kara onto her bed. Alex’s hands never stop roving over her body, touching and squeezing and petting, but Alex’s face still bears a shadow of guilt as she looks down at her little sister’s figure. Kara wonders if she’s afraid Kara is going to regret this. She wishes she could reassure her, tell her that this is what she wants, now and forever, but all that comes out when she opens her mouth is a strangled moan.
Alex’s fingers brush over Kara’s lips and her tongue darts out to wet them as if it’s some instinct that was ingrained in her from the day she was born. Alex makes a desperate sounding noise and replaces her fingers with her mouth.
Kara barely has time to think about the fact that this is her first kiss before Alex’s hands are working at the button of her jean skirt. She isn’t quite sure what to do—how to move her mouth, her lips, her tongue—but Alex takes the lead, seemingly content with the way Kara surrenders to her.
Kara is just getting into the rhythm of it, the kissing and the gentle rocking of Alex’s hips against hers, when Alex’s tongue enters her mouth and Alex’s finger enters her cunt. Kara is expecting neither of these things. It’s a novel feeling in both respects, but Kara knows immediately that she needs more. Her tongue darts out to meet Alex’s while her hand grabs Alex’s wrist and shoves her finger deeper inside. Alex whines, breathy and needy. Her scent is overpowering now, and Kara is sure that her own feels the same way to Alex.
She’s already more than wet enough, so Alex’s finger sinks right in to the knuckle. At first, it’s alright—she feels fuller than before at least, and that’s nice, but then, Alex crooks her finger, pressing against a certain spot inside Kara and Kara’s vision whites out for a second from how good it feels.
“Do that again,” she demands, her grip iron-tight on Alex’s wrist. Alex repeats the motion with her finger and Kara shudders, her head falling back against the bed.
“More, Alex,” she whispers. She surprises herself with the words—she’d never imagined she could be so vocal during something like this, but she knows what she needs and she needs it now.
Alex adds another finger and Kara comes on the spot, her hips jerking erratically as she tries to fuck herself on Alex’s fingers.
It’s not enough. Not even close.
As soon as Kara comes down from her orgasm, she feels even more desperate than before. Alex’s fingers are nice, but not what she really wants. Kara sits up on her elbows and tries to undo Alex’s pants, but Alex jerks away.
“Kara, that’s… I don’t think you’re ready, I don’t know if I’m ready—”
“Shhh,” Kara presses a finger to Alex’s lips. “You’re my big sister. You’ll take care of me. I trust you. I need you. I want you.”
Alex groans and shifts antsily on her feet, palming at the bulge in her pants. Kara scoots forward and wraps her legs around Alex, pulling her closer to the bed again. It’s all she can do not to use her super strength to just make Alex give her what she wants.
It doesn’t come to that, fortunately. Alex lets out a strained sigh and undoes her pants, shoving them down to her feet along with her boxers. Her cock springs free and Kara finally catches a glimpse of it, hard and red and thick. Seemingly of its own accord, one of her hands drops down to stroke it, eliciting a ragged moan from Alex.
Kara presses forward and guides Alex’s cock to her entrance. Alex is still tense, still obviously holding back, until the moment her cock breaches Kara’s entrance, and then it’s like something inside her just snaps. Alex takes full control, holding Kara down by the shoulders as she thrusts into her the rest of the way, forceful enough that Kara’s little body bounces on the bed. Alex’s nails dig into Kara’s shoulders painfully, and her cock is much thicker than two fingers had been, but it feels so good that Kara doesn’t care. She throws her head back and lets herself keen out, sparing no thought for how loud she might be.
Alex’s body arches over hers, pressing Kara into the bed as she fucks into her. Alex’s cock is thicker than anything Kara has ever taken, but she’s so turned on that it hardly matters. She rolls her hips to meet Alex’s on every thrust, trying to force her sister as deep inside of her as possible.
Even still, it’s not enough.
Until finally, Kara feels an insistent pressure inside her on the downstroke of one of Alex’s thrusts. Alex’s rhythm stutters and then stops as her knot swells and lodges inside of Kara. Kara is so full that it hurts. Every little movement of Alex’s hips intensifies both the pain and the pleasure.
Kara bares her throat to Alex, in a futile hope that a human will understand the gesture. By the way Alex’s eyes darken with lust, she gets the message.
Alex grabs Kara’s hips forcefully and shoves her down hard on her cock, grinding its head against that sensitive spot that Kara has just discovered exists. At the same time, Alex leans in and bares her teeth, then sinks her canines into the area between Kara’s neck and shoulder.
It’s bliss and agony all at once. Pain explodes down her shoulder and arm at the same time as another orgasm hits her, causing her to clench around Alex’s knot. Alex’s teeth sink even further into her flesh as she comes too, pumping ropes of hot come inside Kara.
All of a sudden, the pain in her shoulder fades. Alex’s teeth are gone, replaced by a warm, soft tongue lapping at the wound. Alex’s cock is still inside her—her knot won’t go down anytime soon, if humans are at all similar to Krypotonians—but she’s still doing her best to take care of Kara. Her sister. Her best friend. And now… her mate.
Kara may have lost her home, but now she has a new one.