You're sixteen the first time it happens.

By this point, you've been living with the Danvers family for four years and while you still miss Krypton and your parents fiercely, you've managed to adjust yourself well among the humans. Gone are the days when a simple popcorn machine could scare you half to death and you were too afraid to open a door for fear of ripping it clean off its hinges.

Nowadays, you're sure you've pretty much got this whole having superpowers thing down pat. And while you're still struggling with some of the more advanced powers – Kal's infamous Arctic Breath remains ever elusive to you – you're confident that more time on this planet will help you gain control over them when the time is right. Because even though you've decided against using your abilities for fear of being discovered, you're still determined to get a handle on them so as to avoid any undue attention or accidents. You know you were lucky no one saw you that time you took Alex flying.

Of course, the problem doesn't lie with what you can control – flight has always come naturally to you – but with what you can't.

You've never officially shared a room with Alex. When Kal brought you to the Danvers family so you could have a normal, human childhood, their house was big enough to give you your own room. You were grateful for the solitude those first couple of nights. Mourning your parents, your planet, everything you'd ever known and loved with silent sobs and with your fist pressed against your lips so you wouldn't disturb the others.

But over the past few years it has become common practice for you and Alex to migrate to the other's room whenever you feel like it. The first time was when a particularly bad nightmare had forcefully brought you into wakefulness and the thought of being alone on this foreign plane had been too horrible for you to comprehend. It was the first time you'd crept into Alex's room. You could have gone to Eliza and Jeremiah, but they'd already done so much for you and the thought of bothering them with this had sounded impossible.

Alex had seemed a far better idea at three in the morning.

You still remember her face, fast asleep and so peaceful you'd almost walked right back out of there, back to your loneliness and the memory of your planet, your parents, vanishing forever in a red-hot explosion of your own terror. But then, as if sensing your distress, her nose had twitched and her lids had fluttered open and your eyes had met.

You were twelve and she was thirteen, but even then, even though you'd only known one another for a little over two weeks, she'd been ready to protect you. She didn't ask you what happened or why you were there, she just pulled back her covers, scooched over and offered you the now unoccupied side of her bed. You'd been inseparable ever since.

Now, years later, you are sixteen and she is seventeen and it is rare for either of you to remain by yourselves when you know the other one is home. It's no surprise, therefore, that you've somehow found your way onto Alex's floor with your math homework while Alex is working at her desk on a paper for her advanced English class, your glasses slipped so far down your nose they're barely hanging on.

"You know, not that I want to criticize the entire human race or anything, but your math could use a serious upgrade," you say as you continue to fill out the special questions your math teacher had assigned to you personally. You're sure it somehow constitutes as cheating how much further along your own species' math had been and how much of it you had been taught prior to your departure. Human math seems a bit like a joke in comparison.

"See, all I'm hearing is you volunteering to do my math homework from now on, on top of your own," Alex snarks back at you without so much as glancing away from her paper, so in tune to your own frequency she doesn't even pause.

"As if you'd ever let me touch your precious math homework," you mumble teasingly as you smile to yourself. Alex never failed to make a dreary situation just that little bit brighter.

"Yeah well, you know what my mom always says," Alex clears her throat in preparation, "'Alex, you're never going to get anywhere in life as long as you keep leaning on Kara to pull you along with her'." She imitates her mother's voice perfectly and you laugh, knowing how consistently wrong Eliza has always been about who has been doing the brunt of the leaning in your relationship. You might be gifted at math due to your Kryptonian knowledge, but Alex has always been the one to pull you through every tough situation you've encountered on this planet.

After Kal, Alex had been the first person to make you feel safe and at home. Eliza and Jeremiah had certainly helped, doting on you while simultaneously giving you your space, but Alex had been the first friend to truly include you into her life without any reservations. A month after your arrival, when you accidentally broke a glass you'd been holding because you hadn't been careful enough with the tiny, fragile object and your super strength, you'd been too afraid to touch anyone for weeks.

On a logical level, you knew Eliza and Jeremiah hadn't been afraid of you, but your terror had projected your own fear onto their faces. You probably would have refrained from touching anyone for a lot longer, if Alex hadn't made you feel comfortable and confident with her hugs and her patience.

After the glass incident, it took you another month before you felt safe enough to hug her back. It took you longer to initiate contact. The first time you'd felt enough control to hold her hand, she'd given you this brilliant, proud smile and you'd felt as if you could finally do this. Stay on earth. Feel normal.

"Your mom does not sound like that," however, just because Alex makes you feel warm and happy inside doesn't mean you can't needle her from time to time, just to keep her on her toes.

"Does, too! You're just salty because she never complains about you. Must be hard being the favorite child all the time. Never doing wrong, always getting everything handed to you on a silver platter," Alex finally takes her eyes off of her paper to smirk knowingly at you over her shoulder. She wiggles her eyebrows and laughs before you have a chance to hurl a pillow at her head.

"You watch your tone with me, missy," your serious tone is belied by the smile etched onto your lips and she laughs again. "Or else I might have to come over there."

Her smirk broadens and she raises a single, perfect eyebrow.

"And then what?" She asks suggestively and you suddenly can't move.

See, recently there has been this thing between you. This thing where one of you says something to the other and it just seems… weighted. Like it should mean something and you're not quite sure what that meaning could be. Moments like these where there almost seems to be a challenge in Alex's eyes, like she's daring you to go somewhere and you just don't know what she wants to hear.

You laugh nervously and push your glasses further up on your nose, avoiding eye contact. You're stalling for time now; Alex can probably tell. She's turned back to her paper and you can't see her expression anymore, can't see if she's disappointed by your non-answer. Can't tell if you wanted her to be disappointed. Or maybe, maybe you're the one that's disappointed instead, because you're still no closer to figuring all of this out.

You sigh quietly to yourself and look down at your half-finished math homework. Figuring out what Alex wants shouldn't be so difficult. You know Alex, practically know her better than yourself. Hell, you've been sharing a bathroom with her for the past four years, you're practically fused together at the hip.

But you don't know and you can't figure it out and you're frustrated.

You're worried, too, though. Worried that you're making it all up in your head. Worried that talking to her about it will make things weird between you. Will change things. You don't want things to change. You want to be Kara and Alex, dynamic duo, twins of mayhem, dream team extraordinaire. Instead you're staring at your homework trying to figure out if there is some kind of veiled meaning between each and every interaction you've had recently.

You remember Alex's hand on your thigh at the dinner table just last week. How you'd both laughed at something Eliza had said about work and how Alex had nearly choked on her dinner and had put her hand on your thigh to steady herself. You'd always had a habit of falling together. But this time, the innocuous touch had been different. To you, at least. There had been a distinct tingling spreading from where her hand had been. So warm and reassuring. Familiar. Thinking about it now makes your stomach feel fuzzy.

You sigh again, even quieter.

Now that you're thinking about it, you don't want Alex to ask you whether or not something is wrong. You don't know how you'd answer her. Rather, if you could answer her at all. Fact of the matter is, there isn't anything wrong. Not really. Just… weird. Different.

You raise your eyes from the equations in front of you and sneak a look at Alex's back.

She's wearing a white tank top today. It has been hot outside recently. Summer is hitting the city hard and Alex has been feeling the brunt of the sun. Her skin has taken on a golden-brown tan and her freckles have spread more heavily across it, forming new constellations for you to discover. You know she's been working out a lot more, too. Hours spent at the school gym, getting ready for the next soccer season. Alex's muscles have taken on a much clearer definition. They shift under her skin now as she bends to scratch an itch on her left leg.

You don't realize you've been staring for about five minutes at the sun dancing across Alex's back and the sweat gathering at the base of her neck until your eyes suddenly start to burn uncontrollably.

You're sixteen the first time it happens.

You manage to take your eyes off of her back just in time before an avalanche of heat erupts from your eyeballs and two concentrated beams of… energy? Light? Fire? Break through your glasses, shattering them into a spectacular number of pieces and sear two burning holes into Alex's bedroom wall, setting the wallpaper aflame. The frames of your glasses tumble to the floor as you just about manage to clasp your hands over your eyes before you do any more damage to Alex's property. Or, Rao forbid, to Alex herself.

"Alex, please call your mom right now!" You say, your hands still keeping in the heat seeping out from your eyes, now tamed somewhat by the sheer terror cursing through your veins. You know what this is, you just don't know how it happened. Heat vision, Kal's voice rings in your mind.

"Oh my God, Kara, what happened?" Alex's hands touch your shoulders briefly before you can hear her scrambling to the door and calling out for her mom. "Mom! Mom, you need to get up here! And bring the fire extinguisher!" It takes about a second before Alex is at your side again, touching your arms and feeling for any injuries you might have inflicted upon yourself. Her back was turned, she didn't see. Didn't see the way your eyes had been roaming her skin. Doesn't know about the feelings you've been having.

"I'm okay, Alex, I swear. I just- I was feeling really warm and then my eyes just started to burn and-," Eliza bursts into the room. You can only assume she has got the fire extinguisher with her because Alex doesn't move away from you and in the next second you can hear the unmistakable fizzing sound of the small, red machine.

"What happened in here?" Eliza asks frantically as you continue to stubbornly press your hands into your eyeballs. You know the moment is over, know that your eyes won't produce any more of the heat vision at this time, but you're still afraid. Alex is so close to you, what if it happens again? What if you burn her?

"I think this is a new power," Alex answers for you, knowing, as she always does, when you're feeling entirely overwhelmed by a situation. "I mean, Clark told us some more abilities would surface once Kara got older, right? This is just one of those, probably." She tucks you closer to herself and brings your hand-covered head to her chest. Maybe she's afraid Eliza will take you away, now that you've revealed yourself to be a fire demon on top of everything else. Not that Eliza would ever do such a thing, but you understand Alex's sentiment nonetheless.

The fizzing sound trickles off and now the room just smells of soap and smoke.

"I am so sorry, Eliza," your voice is a little muffled by Alex's tank top and your own hands.

"Oh, honey, don't apologize. Just tell me what happened," you can hear her setting down the fire extinguisher and stepping closer to you, her knees touching the floor next to you and Alex as she kneels down.

"I was just doing my math homework and, you know, thinking about stuff," Alex's hands have taken to slowly rubbing up and down your back in soothing motions. You feel more distracted than comforted by her touch, but you don't move away. "And then I just felt this heat in my eyes and bam, heat vision all over Alex's wall." It sounds a lot like an uncomfortable metaphor for puberty to you and you can practically feel your ears turning red in response. You wish, not for the first time, that you could just be normal and have a normal teenage reaction to… what? Some unidentifiable feelings for your sister?

Foster sister, your subconscious whispers helpfully.

"Okay, so we deal with it the same way we always have," Eliza's voice is reassuring and kind. "These aren't uncontrollable, magical powers. Your eyes have muscles and they respond to reflexes. We just need to help you train those muscles, the same way you learned how to fly and how to control your super strength." Eliza's hand joins Alex's, her fingers warm on your shoulder. "I'll get something ready downstairs for you to practice, okay? Just come downstairs when you feel comfortable." With another reassuring squeeze, you can feel and hear Eliza straightening up and leaving the room. You can imagine the looks she and Alex exchange over your head. Eliza has always expected Alex to talk you down when you're scared. You're just not sure Alex is going to be a big help in this situation.

"Okay, kid, let's see if we can't get those hands off of your eyes, huh? Unless you've somehow welded them to your face," you recognize the attempt at humor for what it is, a tactic to calm you down, but you laugh nonetheless. Still, you don't budge. "Come on, Kara. Let's see those beautiful, blue eyes." Your face is growing hot, though this time not out of any desire to do things with your foster sister, things even you can't put a name to, but because Alex has a habit of making you feel unconditionally loved. All the time.

Your hands shake, but you still don't move them.

What if you're wrong? What if this is just a quick reprieve before the burning comes back? What if you're looking at Alex when it happens?

"Come on, Kara," Alex whispers reassuringly, "there's nothing to be afraid of. This is just one more power."

You swallow, hard.

"I don't… want to hurt you," you say softly, chancing a tiny glance through your splayed fingers. You catch sight of your shattered glasses and squeeze your eyes shut again. That could have been Alex's back.

For a second, neither one of you makes a sound. Aside from Alex's soft breathing and her steady heartbeat, all you can hear is the blood pumping in your ears from all of the adrenaline shooting through your system. Then, Alex's right hand settles on your hair, softly brushing a loose strand behind your ear.

"You won't," she says firmly. There is no room for arguments.

Slowly, her hands settle back on your wrists, slowly pulling your hands away from your face. Your eyes are still squeezed shut tightly. By this point, you're about ninety percent sure your eyes won't suddenly burst into flames again at the mere sight of her, but still, you hesitate. Only once her hands settle on your cheeks and lift your face slowly from its downward angle do you slowly start to open your eyes. Her smile is the first thing you see.

Nothing burns.

You're in the garden feeling uncomfortable.

Eliza has set up a wood log from the fireplace on a metallic garden chair. She and Alex are standing on either side of you, your left hand clasped tightly in both of Alex's as you all stare at the log a few feet away from you.

The idea is supposed to be for you to be training your muscles by concentrating really hard on the log, except… what Alex and Eliza both don't get – because you haven't told them – is that your reaction was brought on not by some random thought about your homework, but by your decidedly un-sisterly thoughts. Sexual thoughts, if you're being honest with yourself. You can't say for certain that you wanted to lick the sweat off of Alex's shoulder blades, but really, you also can't deny wanting to lick the sweat off of her shoulder blades. So this is a bit of a conundrum.

It's one thing to fantasize about Alex while she can't see you, but a whole other thing to fantasize about her while she's literally holding your hand. Even worse, Eliza is here.

So yeah, you're in the garden feeling uncomfortable and this is not working.

"This is not working," you say. Out loud.

Eliza nods slowly.

"Well, what were you thinking about when your… heat vision… kicked in upstairs?" You're pretty sure your face is so hot Eliza could fry her usual breakfast eggs on it, and you wisely decide against revealing your uncouth thoughts about her daughter. And her muscles. And the little freckles splayed across her skin.

You can feel your eyes grow hot and give off a burst of energy. The log doesn't catch fire, but two very distinct, black holes now grace its front.

Alex claps you on the shoulder. "See? It's working! Great job, Kara!" Her voice is cheerful, but you feel mortified. This is inappropriate on so many levels, you don't even know how to handle yourself.

You laugh weakly and force a smile onto your face.

"Yeah! Great!" You need so much help.

"How did you get your heat vision under control when you first got it?" You speak quickly and quietly into the receiving end of the phone, all the while trying to ensure that neither Eliza nor Alex can hear your frantic attempts to make sense of all of this.

You'd been forced to stand in the garden for thirty more minutes, decidedly trying not to think any more sexual thoughts while in the presence of your foster mother and Alex. Ultimately, you'd all decided that maybe you should try again tomorrow and you'd been grateful. Alex had seemed more reluctant than Eliza had been, but after a few reassuring squeezes of her hand, she'd given in, too.

That had been about two hours ago. Now, Eliza is taking an important business call in her office and Alex has migrated over into your room to work on her paper. After all, your room doesn't smell of soap and smoke, which probably means that she'll be sleeping over until her room is fixed. The thought is as exciting as it is terrifying.

"Hello to you, too, Kara," Kal's jovial, happy voice floats into your ears.

"This is no time for games, Clark!" Your voice is hushed. You're supremely terrified to be found out before you can get a straight answer out of him.

"Okay, okay," he chuckles, "from your line of questioning, I take it you got visited by the heat vision fairy today?"

You sigh heavily.

"You might think this is funny, but Alex's bedroom wall certainly doesn't," you press your forehead against the living room wall. "Seriously, Kal… What do I do?" He sobers at your tone of voice and clears his throat.

"Well, the fix is pretty simple. You just concentrate really hard on wanting to shoot fire out of your eyes. Boom. Also, maybe, to kick things off and to get you into a position to feel how your muscles need to contract to get the desired effect, you might want to… oh, I don't know, think about someone you like."

Your face is growing hot again. You know it's nothing to be ashamed of, the way that you're feeling. You also know that Kal knows exactly what you're going through because at some point, he himself had to go through it during his teenage years. Still, it makes your skin itch to talk about this stuff. With anyone.

"And there's no other way? I have to… think about… things?" You're being vague and you hate that you're being so vague. But you can't say it, you can't say the words. You bite your lip. "What if I…" You quickly use your super hearing to surveil the house. Eliza is still in her study, still ranting angrily. Alex is still typing upstairs. You're safe. "What if I have feelings for someone in particular, what if it's… inappropriate?" Your voice is barely audible now. You don't want to chance anything.

Kal takes a moment. His voice is kind when he answers.

"Kara, whatever you're thinking, I don't believe for a second that any feelings you're having, for anyone, could ever be inappropriate," unexpectedly, your eyes fill with tears. "I know this is a difficult time. I struggled a lot, too, but you'll be fine. You're a lot stronger than I was at your age." You sniff quietly, but you're smiling again. You're glad you can talk to him about this. He might not grasp a lot of the things about Krypton that matter so much to you, but he understands this. Feeling out of place on a planet that is not your own in a body that is altered by the atmosphere and so very terrifying if you're alone.

"Thanks. Thanks for that, I really needed that," you wipe away the tears and clear your throat. "And thanks for your advice. I definitely need to get a hang of this ability. It just scared me a lot. I mean, Alex was right there, you know? I could've seriously hurt her."

He chuckles knowingly. "Anytime, Kara, anytime. Give Alex and Eliza my best, will you?"

It has now been three days since The Incident and you're still nowhere near being on top of this heat vision dilemma. Sleeping next to Alex certainly hasn't helped and while it is nice when she wraps her arms around you from behind and nuzzles into your neck as you try to fall asleep, it has been an uphill battle the entire way.

So far, you've managed to avoid any further property damage aside from one very unfortunate candle in the living room, which had been standing too close when Alex had decided to stretch and show off her ridiculous abs.

Some time alone in the garden with the log helped you out a bit, but that feeling of guilt overwhelming you every time you thought about Alex in anything even resembling a sexual activity quickly put a cap on those experiments as well. You couldn't even think of anyone else in that way. You'd tried it a few times these last three days. You'd thought of some of the boys and girls at school you thought were hot and that nice librarian lady you'd had a crush on one brief summer when you were fourteen. But no, none of them elicited the same reaction out of you as Alex does.

"You're thinking too loudly and it's keeping me up. How dare you," Alex's voice floats into your ear from where her head is nuzzled into the nape of your neck.

The room is dark.

You're in your bed with Alex curled protectively around you.

It is heaven and hell, all at once.

You've been keeping your eyes shut violently for the past twenty minutes.

"Maybe I'm not thinking loudly, maybe you're just overly sensitive," you fire back at her, though not unkindly. It's not Alex's fault that you apparently like her. You wish you could go back to being confused, instead of being turned on all the time. Being confused at least meant no violent heat outbursts. Being confused didn't mean walking on eggshells around Alex. This whole liking business is seriously starting to piss you off.

"Hardy, hardy, har," Alex says quietly. "But seriously, what's up? You've been a bit withdrawn since your heat vision kicked in. Just talk to me. Maybe I can help."

You snort.

"You really can't, though. Not this time, Alex. This is just something I have to figure out for myself. Kryptonian business. Stuff. And things," you cringe inside. Alex is never going to buy this. You need to work on your lying skills almost as much as you need to work on your heat vision skills. One after the other, though.

"Sounds serious," Alex muses, overtly thoughtful on purpose. "I guess I'll just have to lay here, with you, in the dark, wondering what I did to deserve a sister who doesn't trust me enough to share her innermost thoughts with me." She sighs dramatically and rolls onto her back next to you, pulling her arm away before sighing again. "Oh, woe is me, the mere human, unable to understand those terribly complicated Kryptonian stuff and things."

You grab your pillow and whack her across the face with it.

"You're a jerk," you say, laughing softly at her disgruntled face.

"Hey, you're the one who just whacked me with a pillow! This is straight up violence and I will not stand for it!" She has a dangerous glint in her eyes that always spells out trouble, but you're too intrigued to see where this is going to stop her. You're still hovering slightly over her with the pillow in your grasp, though not for long. In a move born from years of self-defense classes, Alex grabs your wrists and swiftly rolls you underneath her, laughing all the while.

The pillow falls to the floor with a dull thump as your wrists are pinned to the bed beneath you, Alex perched atop your thighs, a joyful, triumphant expression etched across her face.

"I've got you now, wondergirl," her breath hits your face, making your body shudder in her firm grasp. You could put an end to this at any point; you both know this. But you don't want to. You've rough-housed a lot since you moved in four years ago. "Pinned by a human. Now you have to tell me what's been bothering you. Sorry, I don't make the rules." Her grin is cute, her dimples causing your stomach to tie itself into powerful knots.

She's so close to you, her face only a few centimeters apart from your own. Her brown eyes so intense, even in the darkness of the room, the only light coming from the moon shining in through the window.

You can feel the heat again, threatening and loud, roaring in your ears.

Your eyes close quickly, a reflex unthinkingly ingrained into your brain by the last few days.

"Oh," you hear her say quietly as your facial muscles contract, trying to keep the heat contained. "I think I see where the problem is, now." Her right hand moves away from your wrist, her fingertips trailing absentmindedly along your forearm, tickling your inner elbow. Your skin erupts into goosebumps, the heat in your eyes so incredibly unbearable.

"I really need you to stop doing that. Please, Alex," you're embarrassed. You're sure that Alex can tell now, can see what she's doing to you, what you've been imagining.

Her breath is somehow even closer to your face now and her hand has made its way to your cheek, her thumb running over your lower lip. Her own lips skim the edge of your jaw, her hair tickling your cheek. You don't think you're breathing.

"Have you been thinking about me, Kara? Is that what this whole heat vision thing is about?" Her breath is hitting your ear now. You can't move. "You know, I wondered who had you all hot and bothered. I've got to admit," her mouth is on your ear now, you can hear the smile in her voice and clench your thighs involuntarily, "I was very jealous of whoever managed to get you so twisted up inside."

You can't take it anymore.

You grab Alex's face in both of your hands and press your lips against hers, keeping your eyes closed firmly to stop the energy from flowing out of you. Alex kisses you back enthusiastically, her own hands grabbing handfuls of your long, blonde hair, pulling you closer. Your hands slide against her soft skin, one glued to her face, the other one slowly trailing down her shoulder and arm. You tilt your head to the side to find an even better angle. You've never been kissed quite like this. Sure, there have been a few kisses in your lifetime, one even on Krypton when you were nine, but this. This is something else entirely.

You push your lips more insistently against hers, breathing ragged and coming in fast. You don't think you've ever been out of breath on Earth before. Alex's tongue soon joins the mix, carefully licking at your lips, asking for entrance. This is more than you would have ever imagined.

You can still feel the heat, more pronounced now inside of your whole body than focused on your eyes, but you're too distracted by the incessant kissing to notice that the muscles in your eyes have relaxed. Alex's hands slide down your sides, digging into your skin as her mouth makes its way down your throat.

"You have no idea how long I've wanted to do this," she whispers against your skin as she starts lavishing your neck and collarbones with kisses. You swallow hard and try to keep your super strength in check so you don't accidentally squash Alex with your grip.

There is no heat vision when you open your eyes, only the sight of Alex's brown head of hair working tirelessly at your neck.

You pull her away from your skin and back to your mouth. You don't think you ever want to stop kissing her.

The log bursts into flames in front of your eyes.

"Dude, that is so cool!" Alex gasps at the clear blue laser beams protruding from your body. You laugh and relax your eye muscles. You high five her and give her a hug. "I knew you could do it, Kara." If the hug lingers longer than appropriate for two foster sisters, neither one of you mentions it. You're way beyond that now anyway.

"I didn't do it by myself. I don't think I ever would've gotten it down if you hadn't helped me," you blush profusely as you step back from her, meeting her knowing smirk and her cocked hip.

"Yeah well, anything to keep the world safe from my extreme hotness and your extreme lack of chill," she laughs as you softly punch her in the shoulder.

"Hey, don't you think you should be a bit nicer to me now that we're, you know, whatever we are," you haven't really talked about labels or anything, mainly because you're both worried about what Eliza is going to say about all of this. Well, you're worried, Alex is pretty much convinced Eliza is going to rip her a new asshole for failing in her protective duties and ravishing you instead. You smile at the thought.

"'Whatever we are'. Always the romantic, aren't you, Kryptonian girl?" But Alex is smiling and slipping her hand into yours and pressing a long, soft kiss against your lips that makes you swoon on your feet. With her black leatherjacket, her ripped jeans and her converse, she could not be more of a dream.

You're sixteen when it first happens.

Now, you're desperately hoping it won't stop happening for a very, very long time.

If you want to support me, find me on tumblr at goshdarnitjay! Hope you enjoyed!