I've decided to make a collection of Farroncest fics. I figured it'd be better to do that than continuously upload one-shots. Any future Farroncest fics that aren't planned to be multi-chaptered will be put in here, so that includes old fulfilled prompts, prompt requests, one-sentence challenges, etc. Ratings of each will vary. Most of these fics will probably be headcanons and very few of them will directly follow the entire canon plot up to after Lightning Returns. Anyway, here's the first fic.

Title: Secrets
Pairing: Farroncest (Lightning/Serah), Serah/Snow
Rating: M for sisterly incest and some language
Words: 3,251
Song Inspiration: "an xbox killed my dog" - Flying Lotus
Prompt Request: "Post-game - So, Serah and Snow are married. Guess who's having an affair with her own sister?
Infidelity indeed. Do have Serah top—aggressively."
Summary: When Snow's away, Serah will play.

Disclaimer: I don't own the characters in this entire series, so this goes for all chapters.

A/N: Another old prompt that never got fulfilled on the first FFXIII Kink Meme. I've been itching to write this for a while. It isn't specifically post-game but more AU. Also, not sure I really hit the aggressive part, but I'm still pleased nonetheless. Enjoy!

The front door slams shut and keys rattle on the key rack. What a long day. Staff Sergeant Lightning Farron can only take so much stress and lack of sleep. No matter. She's finally off for two days.

She unclips Blazefire's holster and hangs it near the front door. Yanking off her gloves, she tosses them into the living room, and they hit the edge of the couch with a soft thud. She unbuckles her boots, relieving her aching feet of the heavy worn leather. By the time she reaches the bathroom, cape, pauldron, and belt are lying haphazardly across the house. She peels off the sweaty vest and skirt to leave them in a pile on the bathroom floor. Much better.

The shower she takes is the epitome of heaven. Water courses through red-blonde hair, runs down a thin, muscular frame. She enjoys every moment, but it only comes second to a good night's sleep. She throws on a tank top and shorts, exiting the steamy bathroom to the living room. Plopping down on the couch, she snatches her phone from the armrest to check the time - 3:42 a.m. At least that's better than just getting home at four.

Lightning sighs, reclining back along the couch. Her eyes drift and she sinks further into a dreamless sleep.

The front door of the Farron residence opens with a light creak. Footsteps click against the linoleum. The door whispers shut, and a light gasp escapes the 'intruder.'

Serah tiptoes into the living room, nearly tripping over discarded clothing - that darn cape her sister always wears. Careful, now. The closer she gets, the more an apparent snore catches her ear. As she suspects, her older sister, a hardened battle-worn soldier, is out cold on the couch.

The younger Farron tilts her head in amusement, admiring the form she knows so well. A head of bedraggled hair rests tilted on a pillow. One hand hangs off the ebony furniture, the other halfway up the fitting tanktop. Bare legs lie in a tangled heap within a thin blanket at the other end of the couch. The corner of Serah's lip rises just so. Still adorable when she sleeps.

She presses lips to her sister's head, then pulls up the navy throw to mid-chest. Lightning frowns and fidgets. Serah chuckles and leaves her to collect the discarded clothing strewn about the house – gloves, cape, skirt, and vest. I should put these in the wash while she's sleeping. And I guess I'll make her breakfast too.

It's the least she can do, especially considering she now lives with Snow. Lightning can always use the help, no matter how stubborn she can be at times. They are sisters, after all.

Serah takes the pile to the laundry room to start the wash. She returns to the kitchen, eyes darting from cabinet to counter to refrigerator. What would she cook for her beloved sister? Coming to a decision, she prepares the food and cookware.

It takes the better half of an hour before the entire house smells of waffles and breakfast sausages. Admiring her handiwork, Serah leans against a counter. She has quite a mess to clean, but she's confident she can do it without waking her sister. Now to get star-

"Shit!" Somehow, her elbow knocks into a pan sitting on the edge of a counter and it tumbles to the kitchen floor with a resounding clang. Crap. There is no way she didn't hear that. Serah snatches up the pan and sets it in the sink. She tiptoes back into the living room, where a groggy and disoriented Lightning glares daggers at her.

"Ahh- sorry, Light. I-I didn't mean to scare you."

Lightning's hardened expression softens. She wipes a hand over her face. Her voice is deep and riddled with sleep. "You didn't scare me."

Yeah, okay. Serah moves to the front of the couch, and Lightning reclines.

"Serah, it's ten in the morning. What are you doing here?"

Ouch. It's only been a month, and she's forgotten how blunt the soldier can be when she's tired. She's been around Snow way too much. Serah sits on the opposite side of the couch, crossing her legs. "I…haven't seen you in a while. Not since after my wedding. You haven't called very much, and you barely leave texts anymore." She fumbles her fingers. She sees Lightning attempt to formulate words and then stop. Right, she never does speak much right after waking. "I went over to Guardian Corps. barracks today and asked the Lieutenant if you were in."

Lightning hums.

"Amodar told me you'd just gotten promoted recently and had a new work schedule. I just wanted to stop by and…" What is she doing? Oh, just…stretching. Serah's eyes rove over her sister's lax frame.

Lightning lies back and places a hand behind her head. The bolt-shaped necklace she always wears dangles to the side. "Stop by and…?"

"…say hi?" I know she works out, but has she ever been this fit? Serah holds her bottom lip between her teeth.

The corner of Lightning's lip rises. "Say 'hi?' Really, Serah?"

She nods. God, I haven't seen that killer smirk in so long. "Well, it isn't like you call me or anything. You could have told me about your promotion, at least."

Lightning pauses for a second, and then her eyes drop. "You're right. I'm sorry. I'm still getting used to working into the night. That, and I didn't want to disturb you and your time with Snow."

There's no way Serah misses the venomous inflection on her husband's name. Still jealous, of course. Serah giggles. "Claire, you're my sister. You don't have to worry about that, alright? You can call me whenever you want. You know that." Her hand reaches out to trace the curve of Lightning's calf. Just seconds later, she decides to crawl forward, resting on Lightning's lap with knees on either side of the soldier's waist.

"I do know." Half-lidded aquamarine eyes travel up Serah's slim frame. A hand reaches out to the back of Serah's thigh to pull her closer. "What time did you get in?"

Serah flashes a quick show a teeth, her cheeks burning a bright red. "Just an hour ago. Snow dropped me off." Her hands fumble with the hem of the soldier's tank top, and fingers flick the stud in Lightning's navel. Despite Lightning's obvious sleep deprivation, the way her eyes rove over Serah again sets off a slew of butterflies in the younger Farron's belly. I can't even describe how much I missed this. She leans in, lying on top of Lightning, and sighs.

Lightning wraps an arm around Serah's waist. Her voice is husky as she whispers into a darker shade of strawberry-blonde hair. "Can I go back to sleep now? Or are you going to join me?"

A smile creeps upon Serah's face and she laughs. She buries her nose into Lightning's neck, and her eyes flutter shut. "Mmm… I can't." She trembles at the tickling on her lower back underneath her thin hoodie. "Snow's picking me up in a couple hours. We're going to brunch."

Lightning chuckles. "Without me?"

Serah's smile dissipates. "I would have asked you to come, but I didn't think you wanted to see him. Or be within a hundred feet of him."

"You know me so well."

Serah's lips trace Lightning's collarbone. "Mmm, of course I do. Don't worry, I made you breakfast, anyway."

"Oh, first you don't invite me to brunch, and now you're trying to kill me? And the award for best little sister goes to…"

Rising, Serah furrows her eyebrows and pokes her tongue out. What a meanie! Though, she hasn't heard much sarcasm in a while. It's refreshing, to say the least. A nice break from the ever-optimistic and oh-so-charismatic Snow.

Lightning raises an eyebrow. "I'm kidding, Serah."

Serah runs a hand through her hair and giggles. "I knooow." She lowers herself to Lightning's neck, running lips beneath her jawline. "And I missed you so fucking much." Her hand trails up Lightning's tank top, tracing the soft curves of the soldier's abs. A purr escapes her, but the hand on her back ceases movement.

"Ahhh… You're married, Serah." It's almost a growl as it comes out. Almost.

The familiar, commanding timbre of her sister's voice raises gooseflesh on Serah's skin and…who's Snow again? "I don't care. I really don't care."

"Serah."

With a quick peck to Lightning's neck, Serah rises again, crystal eyes studying the lean, muscular frame underneath her. She lowers herself and crushes her lips against Lightning. She grabs one of Lightning's hands, lacing their fingers, and grinds into the older Farron's lap. Fuck, she's missed this, too.

Lightning caresses a thigh, running her fingers under the leg of Serah's jean shorts. Her hand slides towards the front of the jeans, tugging on the zipper.

"Uh, uh." Serah snatches Lightning's other hand, raising it above the soldier's head. "I'm in charge today."

"Says who?" The muscles in Lightning's arms flex as she struggles against Serah's grip.

Serah knows her sister is stronger than her, not to mention Lightning is barely trying; she can feel it. She loses her grip on Lightning's hands, but snatches each arm, crossing them behind Lightning's head, and pinning them with both hands. "Me. Now, be still."

Lightning chuckles. "Forgot I taught you that." She thrusts her hips upwards, nylon meeting dark denim.

Serah giggles. "Can you calm down, soldier?" There's a grin plastered on her face, and she grinds back.

"Yes, ma'am."

Leaning forward, Serah pecks the tip of her sister's nose. "Good." Her lips brush over Lightning's own. She runs a tongue over Lightning's bottom lip and gets a similar response. The kiss is heated and fierce, heavy gasping and extra breaths in between, nothing she's experienced with her own husband. Snow is never rough, never varies, never takes chances. Always too soft, too careful, as if Serah's going to break into a thousand pieces. Lightning is the complete opposite of Snow - soft lips, rough kisses, no annoying stubble. Serah realizes this and shivers, sparks of raw electricity jolting through her.

Lightning rubs against her again, a frustrated growl rumbling in her throat.

Serah grinds back, breaking the kiss. She buries her face into Lightning's collar once more, taking in the musky, sweet scent of rose. It isn't as black and earthy as she's been used to - a scent that is so very not Snow. It's wonderful. She moans into Lightning's neck, releasing her grip and running her hand up the thin shirt.

Lightning's eyes shut, and Serah latches onto her neck. She threads fingers through a darker river of red-blonde. "Ssserah."

Serah nips, licks, bites at the same spot until she's satisfied with the intensity of fragmented moans. A quick chuckle and she's on to the next spot, right above the left collarbone – one of Lightning's favorites. A string of swears whispers past the soldier's lips, causing Serah to plant quick kisses to calm her down. The hand dancing under the tank top rubs the underside of one breast, and Serah has to push Lightning's rising body down. She's missed this, Lightning's reactions, eager and wanting and 'give it to me now.' It's almost comical.

The grip on Serah's hair tightens, releases. Lightning drags the hand up Serah's side, lifting the fabric of the lavender hoodie with it. Lightning snakes the hand around to the front, fumbling for the zipper.

Serah doesn't stop her; it's getting hotter by the second. She leans back, offering to help Lightning unzip the jacket. The zipper slides down and off, and Lightning's hands are on her shoulders slipping the hoodie back. Serah drops it to the floor. She stares at Lightning, every inch, and her eyes lock on to the two angry marks marring the soldier's neck. She purses her lips, aware that Lightning recognizes the look.

"What's so funny?"

"Nothing. Just…" Serah presses two fingers against the marks on Lightning's neck. Trailing them to Lightning's ear, and then under her chin, she lifts Lightning's head. "You're mine, you know that?"

Lightning says nothing at first, just flashes that signature smirk Serah knows would make a plethora of panties drop. "I've always been yours."

"As long as you know." Serah leans in for a quick, deep kiss. She lets go of Lightning's chin to finger the hem of the tank top. "Let's get this off, shall we?" Lifting, she raises the shirt as Lightning lifts herself to allow Serah to remove the bothersome article of clothing. Lightning's nipples are already hard. Serah kisses her sister once before taking a nipple in her mouth. It's a sight she's glad not many people have the privilege to see – Lightning squirming under her lips and playful tongue.

The soldier has nearly been reduced to a mewling kitten. Eyes screwed shut, her hand rests on the back of Serah's head, neck exposed for the younger Farron to do as she pleases.

Serah doesn't miss the opportunity. Her tongue runs up Lightning's neck, and her fingers twist and tweak at both nipples. Her ministrations earn her a light, strained sigh that's music to her ears. She definitely can't get this out of Snow.

Lightning thrusts her hips once more. "Ssseraaah…"

Serah's already gotten the hint – a plea for release. She plants her lips on three places of Lightning's neck, on each breast and in-between, above her navel, and just beside her hipbone. Oh, how she adores the way the woman writhes and squirms under her. But Lightning's suffered long enough. Serah shifts back, sitting more near Lightning's knees. Her hand reaches out, caresses the smooth, heated skin. One finger travels from the valley of Lightning's breasts down to the silver gleaming stud and further to just beneath the black shorts. Past the mound of light hair, Serah teases her finger over the slit.

Lightning sighs, a content gasp of air on the verge of becoming a moan. She can't hide her current desperate state from her sister. Serah knows her too well.

Serah removes the finger. "Oh, poor baby. How long has it been?"

"You…should know how long." Lightning sets a hand behind her head.

Serah's eyes widen. "The night before my wedding?! You can't be serious." Well, that's been…a while. Too long for anyone with a libido as high as her sister's. Lightning has had zero action in the last few weeks while Serah's been out having her fun with Snow. Of course, they're married now, but she can't just leave her sister alone like that, especially when she's able to see Snow every day.

Aquamarine eyes stay fixated on the smaller frame. Hell, even Lightning's stare is pleading.

"Don't worry. I'll make it up to you, okay?" Teeth click together in the kiss the two share. Serah's finger is back, stroking the wet slit with care. She grins at the moan she receives and takes it further. Finding that opening, she slides her finger in, watching Lightning arch her back beneath her. Cute. Still the flexible panther as she remembers.

Lightning throws her hand back on the armrest. Her moans resonate throughout the living room as she jerks her body to meet Serah's thrusts.

Serah licks her lips at her sister's writhing. She cups one breast in her hand, massaging it between her fingers. Swear after swear fills the room, and Serah snickers under her breath.

Lightning hears her of course, makes eye contact for just a second. Her face glows a soft pink, and she turns her head to the side just in time for another finger to be added. She shuts her eyes, clawing the armrest harder than before.

Serah's pace increases. She gives one major thrust before stopping.

The soldier's eyes grow wide, and she's panting, sweat beading her forehead. "Serah!"

"Hmm? What's wrong?" Fingers still buried inside, she curls them, massaging that spot, and earning a deep rumbling groan from beneath her. Perfect. Lightning is nothing but putty in her hands.

"Fuck…Serah."

That's all she needs to hear. Serah rubs the spot again, thrusts into it, and leans in close. Lightning's heart is hammering away in her chest; she can hear it. Serah plants one kiss between Lightning's breasts. Her tongue darts out, and she's licking a trail up to the moaning woman's neck. One kiss, a lick and chuckle, a playful bite. She shakes from the sudden shudder under her. A strained moan, breath tickling her ear. Lightning tightens around her fingers, squeezing. One more shudder and Lightning settles down, breaths coming in short gasps.

Serah slides out carefully, fingers slick from her sister's orgasm. Tongue cleaning each digit, she laughs at the near-silent 'fuck' that paints her sister's lips. It's just as she recalls, tangy and soft, a hint of sweetness within. Snow doesn't even compare.

Serah moves to her original spot on Lightning's lap. "Did you miss me?"

"…Yeah…" Lightning grabs the back of Serah's head, marking the younger Farron's lips with her own, tasting the mess she created just seconds ago.

"Nnng… How much?"

"So much."

Serah's lips curl in a smile, and she pulls away. "So, how was that?"

"Come back here." Lightning pulls Serah closer to rest her head against Serah's. One deep and passionate kiss, and her hands are roaming.

The kiss breaks, and Serah giggles. Warm hands trail up her back and down again to claw at the front of her denim shorts. It takes a lot for her to ignore the creeping wetness between her thighs. "Mmm… Not today, sis. I have to go soon." She pecks Lightning's lips. Removing the hand from her shorts, she grazes her teeth along the outer shell of her sister's ear. "Next time I'll eat you, okay?"

The elder Farron drags her lips over Serah's neck. "That a threat or a promise?"

"Haha! Promise, babe." Serah pulls away from Lightning and rises. "Now, go back to sleep. I know you're still tired." She runs a finger down Lightning's chest and abdomen and stands, stretching sore legs. "Want your shirt?"

"Leave it. Come sleep with me."

Etro, she's making it even harder to say no. But…she can't. Not yet. Serah's already promised Snow. And, well, she knows Lightning, and Lightning still isn't very fond of her husband. "I have to get ready, Claire, go to sleep. I'll lock the door when I leave."

There's a deep rumble in the soldier's chest before she responds. "Fine."

"Sorry." Serah leans down to capture Lightning's lips in a quick and heated kiss. "Don't forget I made you breakfast. And your uniform is drying."

Lightning nods.

"Love you, sis." She stands, returning to clean the mess in the kitchen.

Serah showers and dresses, entering the living room less than an hour later to find her shirtless sister passed out and snoring. She wants so badly to curl up next to her, sharing that little bit of space and warmth with the person she loves so much. Of course, she loves Snow, too, but…it isn't the same. The love she has for her sister drives so much deeper than anyone can bare to imagine, least of all, Snow.

Sighing, she ambles out the front door, locking it behind her. It's only been a second and she misses Lightning already. Misses every gentle touch and rough kiss, sarcastic remark, protective and jealous glance.

Everything. So fucking much.

And for those of you who might be waiting on "Bonding," the chapter is finished, but it needs to be heavily edited. I can't look at it without cringing, to be honest.