Offline/Ask what she expects you to do about it
"Well what am I supposed to do?"
"Can you look? It's really hard to see."
You sigh then nod. She's practically been fingering her slime into her cooch this whole time, so you're not surprised by this turn of events. But it's only now you consider that guys have a much easier time examining their junk than girls do.
Emma spins toward you, shuffles closer, and parts her legs. She then tucks her arms under her thighs and grabs onto each of her lips with her fingertips then unabashedly spreads her vulva apart with gusto. You're now staring straight into your sister's tiny little hole. She doesn't look anything like any of the porn you've seen. Vaguely, sure, but there's much less detail. Her features are so small, not all there, and such a bright pink. Her skin is tight, stretched taut, and looks tender having already been poked at for half an hour. You tentatively reach out and rub the shallow stretched out crack between her outer and inner lips, the latter being little more than a ridge that circles the hole beneath her clit, her love nub still hidden behind another tight patch of young skin.
"Do you see anything?" she asks.
"Not really," you admit.
She shifts her fingers and resecures her grip, stretching wider and trying to look down. "It still feels so gross though. Maybe... can you try?"
"You want me to... feel for it?"
"I guess so," she nods.
With a careful touch, you pinch and stretch her already taut, subtle folds this way and that in search of anything blue. She's already wide open and there's not much of her you can really move anywhere, but part of you just wants to get a better sense for what pussy feels like. Her inner folds are soft yet almost clammy, supple sensitive skin that feels like the inside of your cheek as much as anything. You rub at the skin over her clit a little then tickle her pee hole and scrape along the insides of her lips with one finger. There are miniscule bits of slime here and there, but surely nothing she could actually feel. Then you go for it. You push inside her.
Emma gasps slightly when you enter her, a surprised shallow breath. You take it slow, sitting on your first knuckle of your finger for a moment before sinking deeper. After the second knuckle you start wiggling around, completely unsure of what slime is supposed to feel like inside of a vagina. There's only a few seconds of honest searching followed by many more just having fun exploring your first real life pussy. Too bad it's your sister's.
"Do you feel it?" she asks, adjusting her fingers for you.
"I dunno. I don't think there's any more slime sis."
Despite that admission, you stay locked like this for a while, your sister sitting crouched forward holding her young pussy open so you can probe her tight little hole. She clenches your digit a few times, but you can't tell if it's on purpose or involuntary from your repeated movements. Neither of you say anything. Quiet wet sounds can be heard when you slowly start to move in and out of her entrance in a more steady rhythm. Her breath falters every now and then, her insides gripping your solitary finger for everything it's worth, but the source of those sounds you hear help your finger to glide smoother and easier into her hole.
"Oka-ay," she finally responds, shuffling backward to slip your finger out of her. She cups her crotch and you only now notice her face is beet red. "I have to... go pee." She gets up and walks right out the door butt naked.
Fuck are you hard. You whip open your sister's sleeping bag, rip off your boxers and start beating your meat. You're already so close. You reach down and grab your sister's panties to use as a cum rag when Emma walks inside again. You keep going for a couple seconds staring defiantly at your naked little sister while you masturbate, but... you can't do it. Seeing her eye you up with shock is too much for your guilt to take. You stop, sigh and look away.
Emma takes a few cautious steps toward you then crouches down and pulls out her pink slime.
"Here. I don't care about Sparkles."
What a weird yet considerate gesture. You gaze at the goop in her hands for a moment then reply, "Can you, like, hold it for me?"
Emma complies while you get up onto your knees. You inch toward her until the tip of your cock pushes into her handheld slime ball. You stare down at her fingers, dainty and fragile looking beneath your cock. You also peek at her very pink bald pussy lips framed between her crouched legs, a very different angle to what you just saw a minute ago. She stares down at your member while you start jerking off again, your glans embedded in slime. It takes a minute for you to work through the awkwardness of jerking off in front of your sister while you're both butt naked, but soon you grunt and moan and blast Sparkles with your spunk. Your seed is literally injected into the womb of the pink slime ball in your sister's hands.
"Oh my god," you exclaim, finishing off a few more shots with a shallow buck of your hips. Emma doesn't say anything, just watches with interest. Finally you sit back, panting slightly, your erection still pulsing. "Thanks," you add, as much an apology.
Emma folds the slime over then stretches it out, spreading your spunk throughout the goo. She forms and squeezes a ball, bits of your semen oozing to the surface, then kneads it all back together between her hands. Watching your naked sister innocently play with your sperm filled slime brings a twisted level of disgust and arousal you've never felt before. She's unknowingly getting you ready for another round.
"Was that fun?" she asks, simply curious. You answer and she puts the slime back in its bag, storing it again for later.
Despite the fun, guilt is still at high levels. The two of you don't talk much, both getting dressed shortly after your dick shrinks back to normal. You head back to camp mid morning and are forced to wait around again for food. Some of your older cousins make small talk. Jet's girlfriend Hannah corners you for a while and asks you all sorts of questions, is way too interested by what you have to say and laughs at things that aren't that funny. You even think she might be flirting with you, but that seems so unlikely. She sure is trying super hard to be liked.
Lunch is lackluster but afterward Emma convinces you to play with her and Asha. It quickly devolves into them play fighting over (and on) you, but it's something to do. You get a bit of a chub with two girls grabbing at you and climbing up you, but at least you found some relief this morning.
You all spend some time in Asha's cabin goofing around. A bunch of kids sleeping bags are all crammed in here together, seemingly by choice. You imagine this to be where Emma would've ended up had you not drug her into the bush with you.
Partaking of some frisbee allows you to escape little girls for a while and find some space. Then dinner comes along and smashes everyone together again. Tonight gets especially rowdy, in more ways than one. Something ends up happening with Asha, the poor girl found throwing up in her cabin later in the evening. Maybe something she ate didn't agree with her. A bunch of kids are then pushed out into the wilderness in a spare tent to let the cabin air out but they don't seem to mind at all, finding a spot well away from camp and carrying on as much as the adults.
With Asha sick, tended to by her mom, Emma clings to you with additional fervor. It's really more like a buzzing bee, obsessed with a flower, moving in and around it constantly and always making noise. You do your best to tune her out and after you both horse around with the other kids for a while you spend a long time next to the campfire. What keeps you there is easy access to a cooler where you manage to sneak beer into cups for both you and your sis. She says she doesn't like it but she drinks what you hand to her it anyway. You can't say it's great beer yourself, but you haven't had much beer before either, and you're feeling just rebellious enough to exploit your access to this strange sophisticated beverage for all it's worth.
You drink through the night and get decently buzzed. Uncle Mike catches you filling a cup at one point but he doesn't stop you, just tells you to take it easy, and thankfully doesn't catch you passing it to your sister. You and Emma stay up a lot later than normal and watch the campsite die down. She's acting pretty silly when you both head back to your cabin sometime after midnight (you assume; you don't have a watch).
She slams herself dramatically against your cabin door to block the entrance. "I don't wanna go to bed! Let's do something!"
"It's way dark, but... whadjou wanna do?"
She swings her hips to and fro rubbing her butt on the door. "Ummmm... umumumum... Let's go swimming!"
"It's the middle of the night, Em! Besides, didn't you tell mom that you forgot to pack your swimsuit?"
Emma turns around, mouth wide open, eyes twinkling like the stars. She jumps out at you, grabbing you around your waist and hangs down to the ground with her head thrown back.
"Lez go skinning dipping!"
"Are you serious?"
"Yeah! That's when you get naked right? Let's swim NAKED!" she screams in excitement.