Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/10227194.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      F/F
  Fandom:
      Supergirl_(TV_2015)
  Relationship:
      Alex_Danvers/Kara_Danvers
  Character:
      Alex_Danvers, Kara_Danvers
  Additional Tags:
      Sister-Sister_Incest, Pseudo-Incest, it's_not_incest_if_one_of_them_is_an
      alien, Masturbation, Mutual_Masturbation, Phone_Sex, Hints_of_praise
      kink, Hints_of_voyeurism, The_Internet_Doesn't_Actually_Have_EVERYTHING,
      Repression, Denial, Guilt
  Series:
      Part 2 of Don't_Dream_Too_Deep
  Stats:
      Published: 2017-03-11 Words: 2988
****** Holding You With My Voice (And Then Letting You Go) ******
by Silent-Wordsmith_(Shatteredsand)
Summary
     Alex has been back at Stanford for a while. She’s been putting
     thoughts of Kara to the back of her mind for weeks now, ignoring all
     the feelings she refuses to acknowledge as she drinks herself into
     the kind of stupor that allows herself to take another girl to bed,
     to moan incoherent syllables instead of a name.
     And, then, Kara calls her.
Notes
     My poor Ace Soul is drowning in alcohol to keep the smut coming (pun
     one hundred percent, fully intended).
It’s a Tuesday night, mid-March, and Alex is staying in to study because
there’re no good parties to found on an Tuesday night—Alpha Capa Delta
sometimes tries, and always fails to deliver; Alex has made the mistake of
trying to find a good time at one of their Tuesday parties before—when her
phone rings out Kara’s special ringtone. Alex pulls herself away from her
textbook, eyes scanning the room for wherever she’d tossed her phone when she
got back from class.
She catches it on the last ring, bringing up to her ear with a breathless
“Hey.”
“Alex?”
“Yeah, Kara, what’s up?”
A heavy pause. One Alex is used to. Kara has spoken fluent English for years,
but, sometimes, there’s still a pause, a delay, as she translates what she
means—in Kryptonian—to what she says—in English.  “I can’t do it.”
It’s a whine, and Alex would be more sympathetic if A, she didn’t have finals
fast approaching and B, she any idea what Kara was talking about.
“Can’t do what?” Alex breathes out, exasperated. There’s been a lot that Kara
thought she couldn’t do, only to find that she could, and do it well. Alex
doesn’t mind playing the role of cheerleader, the alien’s personal pep squad
for all things human and, therefore, alien to her. But she needs some kind of
context or she’s useless, and she doesn’t have the time to be useless right
now.
A drawn out silence, different than Kara trying to parse from her first tongue
into English—heavier, somehow—Kara’s soft breathing the only sign that she
hadn’t hung up.
“I can’t…” Kara trails off, huffs out a heavy sigh, one that Alex thinks might
be mortification. “I can’t…masturbate.” She finishes quietly, barely audible to
the human ear. 
“Oh.” Alex breathes in deep, trying to pretend she doesn’t feel the way she
does. This is normal. This is her sister, growing up and asking questions. “I’m
so not the person to talk to about this.”
Alex doesn’t trust herself with this, with Kara’s
emotional—sexual—vulnerability. Her thoughts still stray to golden blonde hair
and bright blue eyes when she needs to get off, her mouth still clamps closed
with drunken co-eds to stop herself from moaning the wrong—right—name in the
late night/early morning of her meaningless trysts. She isn’t someone who can
talk to Kara about this, not objectively, not rationally, not the way Kara
deserves.
“Well, I can’t do it myself.” Plaintive, an alien still struggling to
understand. It makes Alex ache, with sympathy, with want.
“It’s called the internet, use it.” Battling against the part of her that wants
this, wants Kara desperate in her ear, wants Kara to look to her always, for
everything. It’s not right. It’s the height of wrong, and Alex is better than
that. More, Kara deserves more than that. More than a would-be, should-be,
sister who lusts after her. For all she looks like a young adult—for all she
looks like someone Alex should be, is allowed to be, attracted to—she’s still
just a kid. Someone with fewer years on this planet than a kindergartener—and
Alex isn’t allowed to want her the way she does. It’s wrong, and manipulative,
and borderline abusive. It’s taking advantage, at best. And Kara deserves so
much more than her foster sister whispering vileness in her ear in an attempt
to coerce her into feeling the same, broken way Alex does.
“I tried; it doesn’t work.” It’s practically a whimper. Kara so needy as to
make every part of Alex ache with the desire to reach out and fix everything
that could ever be wrong with the younger girl’s existence. It’s not right,
it’s more than an older sibling should want to do. But Alex has never managed
to fit Kara into the category of little sister, and it continues to bite her in
the ass. There’s nothing Alex doesn’t want to do for Kara, everything: big or
small, innocent or sinful, Alex wants it all so long as Kara is smiling, so
long as Kara is happy.
“What do you mean it doesn’t work? It’s the internet; it has everything!” Alex
needs a way out of this conversation before it goes past the point of no
return. The point rapidly approaching as Alex tries not to get involved in
this—in Kara’s sexual awakening—and finds herself trapped in the middle of it
all the same.
“Does it have an alien category? The real kind, not ambiguously alien that’s
completely human except for the weird coloring and affected accent?”
She has a point, however much Alex doesn’t want to admit it. There’s not much
realistic alien porn out there—it’s all green body paint and cheap prosthetic
horns—nothing like the real aliens, aliens that look and feel like Kara. Not
that Alex had looked. Not that Alex’s internet search history had “humanoid
alien with super powers; porn hub” all over it. Not that Alex cared whether
there were convincing portrayals of aliens and humans having the best sex of
their lives with each other. Not that Alex was invested at all.
“I see your point.” Alex reluctantly admits. She doesn’t want to talk about
this. Talking about it is dangerous, could lead to Alex saying things she
shouldn’t. Things she couldn’t take back. Things that would ruin her and Kara. 
“Can you help me?” So soft in her request. So hesitant. Alex hates that, hates
that Kara thinks there’s something—anything—Alex wouldn’t give her. But this is
something else, something more than Alex should give.
Her mother’s voice at the back of her mind saying sister, saying help her,
saying she doesn’t understand and you have to help, saying sister sister sister
sister on endless repeat until Alex felt wrong with every thought, every
breath, every curl of her fingers and hitch in her breathing.
“Of course I’ll help you.” It’s instinct to say it, to mean it. Half a decade
of being told to help Kara, to be there for Kara, to do anything and everything
for Kara. Alex doesn’t know how to say anything else, however much she knows
this is a bad idea. A terrible idea. The worst idea.
Helping Kara get off, listening to Kara get off, means that Alex won’t be
capable of thinking of anything else. She knows that, accepts that. Buries her
own problems—finals fast approaching, the inevitable requisite distance
demanded between them, the way this is going to fucking wreck her—and puts Kara
first, the way she always does. This is not okay. This is the crossing of a
boundary few ever even understand exist, let alone reach. But here, now, Alex
stands at the precipice of it, listening to Kara’s quaking breathes, and she
can deny her nothing for anything.
“What. What should I do first?” The first tremblings of a question.
That is exactly the kind of question Alex doesn’t need to hear her should-be
little sister asking her through the phone. Not like this. Not in a tell me how
you want me to touch myself way.
Fuck.
“Start slow.” Alex says—orders?—half out of her depth and half desperate to
follow her own damn advice as she feels the heat beneath her navel building.
“Light touches. Just your stomach, your thighs, maybe your breasts.” A deep
inhale, “maybe your nipples, if you think you’ll like it. Focus on what feels
good, Kara. It’s about. It’s about feeling good.”
“Mmm.” Kara sighs gently, and Alex wants to throw herself out a window to stop
the way that makes her feel. The not unexpected but unwanted gushing in her
panties and the clenching in her thighs as he aches for something that isn’t
there and never will be. Never can be. “Yeah, okay.”
Alex can’t hear much for a few long moments, but she can hear enough. The
slight sound of shifting sheets—shifting clothing?—as Kara follows her
directions, the soft breathing of her foster sister as her touches herself—dear
gods, Alex is listening to her touch herself—and, if she strains her ears,
maybe, the sound of fingertips running over preternaturally smooth skin.
“Are you feeling good?” This is, perhaps, an unnecessary question, closer to
something like the phone-sex they definitely aren’t having than an older
sibling trying to talk their sister through their first go at masturbation. But
Alex wants to know, needs to know; gods above and below damn her for it.
“Yeah.”  Another soft sigh, barely audible but present. Alex hears it. Alex
hears it, and Alex clenches on nothing, and Alex wants this to be something
it’s not. Alex wants this to be something less than it is.
Alex just. She wants.
“Good. Good girl.” Swallows thickly, because she hadn’t meant to say that last
part, that part’s definitely not okay, even more than the rest of this. “Are
you playing with your nipples?”
“Yes.” A hiss this time, and Alex doesn’t want to imagine her pinching her
nipples, pulling at them a little, the way Alex would if she thought she could,
but she does. Fuck her to hell and back, she does.
“That’s good.” Alex is struggling to keep her voice even. If she sounds
unsteady Kara will get worried, Kara will stop. Alex doesn’t want her to stop.
“Now, move a hand down from there, Kara. Slowly.”
“Mft.” Kara makes a sound between a moan and a groan and, shit. Shit. Fuck.
Alex can’t do this. This is wrong. This is ten times worse than thinking about
Kara when she’s with nameless coeds or by herself. This is an active
corruption. This is something she can’t do. She can’t, she can’t, she can’t.
“Alex.”
She can’t stop.
“Keep going, Kara.” Alex breathes out, hoping that Kara is too distracted to
notice the quality of her voice. “Slip into your panties.”
“I’m not, I’m not wearing any.”
Jesus.
Fucking.
Christ.
“Oh. Okay. That’s, that’s good.” That’s so good Alex might actually die. “Touch
yourself, touch your cunt.”
Alex doesn’t even know if Kara knows that word; it’s hardly likely to have been
on her vocab worksheets. But she seems to get the idea because she’s
moaning—she’s moaning—out, “oh, oh!”
“Yeah, that’s it. You’ve got it. You’re doing so good.”
“Alex.” Panted into her ear, painted in desperation, in Kara’s voice, and it’s
all Alex can do not reach her hand into her own sopping underwear.
“Yeah? That feel good? You feel good?”
“Rao, yes.”
“Just play with it a little. Run your fingers through the folds, Kara, feel
everything.” Feel everything the way she wants to but will never, ever allow
herself to.
“It’s good, Alex. It’s so good.” Kara says, pitchy and needy and everything
Alex has ever wanted to hear from Kara but never even dared to hope for.
The ache between her legs is getting harder to ignore, but this isn’t about
her, can’t be about her. This is about Kara. This is about helping Kara. If she
touches herself, it’s another line she can’t uncross, another failure to be a
good sister—hell, a good person, even—and Alex has enough failures stacking up.
“Are you wet?” Another unnecessary question. Kara sounds wet, she sounds ready.
She sounds like Alex could fit two fingers in easy, maybe three.
No, not Alex. Like someone, like someone else, could. Someone definitely not
Alex because this is not about her.
“So wet.” Kara’s starting to sound a little out of it, a little lost. Like,
could accidentally bruise Alex in her need, out of it. Like, would fuck a
little too hard—just hard enough for Alex—out of it. Like, inhumanly strong and
slightly too fast—the way Alex wants it—out of it.
Alex couldn’t keep her hands off herself if she tried. And, gods, she tried.
She tried so hard.
This is wrong, this is wrong, this wrong.
This is the worst thing she’s ever done.
But she can’t stop.
Gods, she so wet. She interposes Kara’s sounds over the feeling of her own
fingers sliding through her soaked folds, circling her entrance, edging at her
clit. Fuck. Fuck.
“Touch your clit, the little bump at the top. Can you feel it?” The answer
comes in the form of uttered Kryptonian, something Alex is eighty-percent sure
is a swear. “There you go, Kara. There you go.”
Alex can feel herself getting closer, just listening, just knowing what Kara is
doing. But she knows she can’t come before Kara does, she has to see this
through, has to make sure the call is over before she loses herself.
“Rub at it, as hard or as soft as you like, as fast or slow as you like.
Experiment with it for me.” Shit, that was out of bounds in the worst kind of
way. In a way Kara might notice.
For me.
Like Kara wanted Alex to be the one doing this to her. Like Kara wanted Alex.
“Rao, Alex.” She doesn’t know exactly what Kara’s doing, but it must be working
for her. Must be going exactly right. And Alex gushes again at the idea that
she did that, she made Kara feel this way, with her words, her direction, her
care. However fucked up it might be. “I feel so…”
Kara trails off, unsure of her words, or her feelings, or both, and Alex has
never felt closer to coming harder than ever before than she does right now
with barely a graze of her fingertips and Kara sounding like that in her ear.
“Close, Kara.” Alex gasps out, beyond caring about morality, about right or
wrong or which side of that very thin line she’s on. It’s half finishing her
foster sister’s sentence and half just, telling. She’s so close, and she going
to come so hard, and she needs Kara to go first so Alex can hang up and finish
and call back like it was an accident. “You’re gonna come, Kara. You’ve done so
good, and you’re gonna come for me.”
For me.
Again, words she shouldn’t have said, wasn’t supposed to have said, couldn’t
stop herself from saying.
A whimpering whine on the other end of the line, Kara as desperate as Alex has
ever heard her. More. Hovering over the cusp on her first orgasm. Her first
orgasm, the one that Alex had talked her to, the one that Alex was going to
bring her over.
“Do it, Kara.” Alex is panting, gasping, groaning, so close and so eager, and
so damn close. “Come for me.”
And Kara, Kara does.
Alex can hear it.
Alex can hear Kara. Kara, crying out “Alex, Alex, Alex, Alex!”. Kara, moaning
out in her native tongue a slew of lilting words that Alex can’t understand.
Kara, falling apart under her own hands and Alex’s direction.
The wet sounds of her release, barely caught over the phone’s shitty mic and
Kara’s voluminous barely-not-shouts.
Alex can hear everything.
And, fuck hanging up and waiting. Fuck pretending it was an accident. Fuck
pretending that she’s not coming harder than she ever has in her entire life to
the sounds of her foster sister coming like a freight train over the phone.
“God. Fuck. God. Kara!”  Alex doesn’t mean to shout—to scream—but she’s grown
too accustomed to the privacy of her dorm. She doesn’t have to answer to Eliza
here, she doesn’t have to explain herself to anyone. If she wants to have a
screaming orgasm, she can, whenever she wants.
Her hips are still jerking lightly against slack fingers as she comes down, as
she tries to level her breathing, as she tries to ignore that this had ever
happened. But her body’s quivering, and her chest is heaving, and her hips are
still twitching forward like the best orgasm of her life was only a precursor,
and Alex knows she’s never going to forget a single second of any of it. Not
one second from the moment her phone rang until now, with all of her except her
head so ready for the main course after the delicious appetizer. The main
course of fucking her foster sister like she’s always wanted. The main course
that is never going to come.
Fuck.
Alex looks at her line in the sand, obliterated by her tidal wave of lust and
love and come, and tells herself she’s not allowed to cry while Kara’s still on
the line.
“Alex?” Kara says, soft again. The need gone, banished either by her orgasm or
her concern for her sister—her sister, that’s what Alex is supposed to be—Alex
doesn’t know. It doesn’t matter anyway.
“Yeah, Kara, I’m here. Everything’s okay. You did great.”
“Are you sure?” The tremble of uncertainty, the idea that Kara could even
question it, almost has Alex opening her mouth to tell her how good she was.
How she made Alex come undone with almost just her sounds. How it was so good
Alex was helpless against touching herself, getting herself off. How Alex just
had an orgasm better than any other she’s ever experienced and it was all
because of Kara and how good she was.
But Alex grits her teeth, and Alex bites her tongue, and Alex says “Yeah, Kara.
Really knocked it out of the park.” And Alex forces herself to smile, even if
Kara can’t see it, and emphatically doesn’t think about who else Kara might
come for. Who else might make Kara feel the way Alex just did. “You’ll be a pro
in no time.”
And then Alex says her goodbyes to a sated, bone-tired Kara, and Alex hangs up,
and Alex masturbates like her own hands and her own memory and her own
imagination are ever going to be enough to make her come like Kara just
inadvertently did.
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