Okay, for my first Transformers fanfic, I have no idea how this happened (and I am working on another, more mainstream fic). I think I can blame it on too much pondering of AU's and the nature of the twins relationship.
To make it clear, this isn't a strictly Human!AU, the bot's certainly look humanoid. But I imagine them more as techno-organics the way Sari is in TF:A. Its a personal AU I've been working on inside my head the past month or so regarding the idea of if Primus had decided to go another route in creating his children. More android than GIANT ROBOTS.
The genderswitch is purely random because... damn if the Transformer's cast isn't entirely unbalanced in the male persuasion, at least going by G1 where they technically have genders. If I post more from this AU there'll be other genderswitch, I mostly went with characters I felt fitted into the female persona best. There will still be slash and all that good stuff though.
Most importantly, this fic examines a very taboo subject. It was an excercise in writing for me to imagine two people in such a situation, surrounded by a society that might very well hate them for feeling the way they do. If incest/twincest (particuarly the m/f kind) makes you uncomfortable, I'd advise not reading any further.
That said, for anyone who does decide to give it a go, I hope you find it interesting.
"... 'Sides!"
"Shhh... Sunny... gotta be.. uh, quiet!"
"There's... there's no one here... ah!"
"I know but-"
"Oh 'Sides!"
Slag it. Sideswipe groaned and tightened his grip on his twin's hips, fingers digging in through the flimsy material of her pale yellow sundress. The one that so perfectly complimented the brighter shade of her hair, lightly tanned skin and sultry teal eyes. It was the one that drove half the Autobot's on the Ark crazy, barring those too old to go chasing what their race considered near jailbait.
But right now it was only them, them and Wheeljack who they knew was absorbed in whatever explosive product he'd gotten into his lab this time. Everyone else had been called away to intercept a large-scale Decepticon attack on a power plant on the other side of the continent. That had been two days ago, meaning - since word of a successful defence had been sent home - they could return any moment now.
Sunstreaker and Sideswipe had been ordered to stay behind, to deny them the joy of battle for their latest string of offences had been Prowl's idea, and it was partly the desire to spite that which fueled the one elicit side of their activities that no one else knew about. If anyone did find out... well it made the twin's quail to think of the possible consequences, worst of which was being seperated far away from each other.
It wasn't their fault, this need which drove them to this, they were born this way. Two beings cruelly split into half, sparks constantly calling to be one again but unable to reunite. The closest they could ever come were these quick, dirty encounters, too frightened now they were surrounded by others of their race to be anything other than fast and rough about it. Most of their compatriots thought it a little weird they shared a room, if they knew they shared a berth in that room as well... they always took care to make sure both looked used and clearly seperated by posessions.
Sideswipe sometimes wondered that if his sister had been born a male like him, would it be any easier to accept, but no... Cliffjumper often liked to joke that Primus must have seen fit to take Sideswipe's feminine side and put it in another body when he was born, to save him the embarassment. The redhead usually ended up in the medbay courtesy of Sunstreaker's fists soon after. Regardless, he loved his sister, too much, he wasn't even sure he could call it love, this driving need to be one with her when their bodies had been apart too long.
It wasn't quite as bad as when they'd been in the gladiator pits, under leering eyes and cruel touches as they fought for their lives every single day. But still they felt the watchful gazes and felt the paranoia that rose up as morality would storm in to seperate them. Neither could stand the thought, so they were careful. But their frustration acted out in their own seperate ways, Sideswipe's manic sense of humour and wild pranks, Sunstreaker's dangerous temper and bordering sociopathic tendencies that earned her the reputation of the cruelest bitch this side of the civil war.
So when they were alone like this, they clung to each other, spending their passion and hunger as safely as possible, far from prying eyes. Though this time, the dark haired twin had to omit, a corridor in the Ark wasn't a particularly private setting.
They both had a hunger for risks though, heightened by each careful step they were forced to make to hide the true extent of their bond. Still, the thought of Prowl's face if he knew they had done this here was enough to vindicate the act, even if they both silently agreed they would never get the satisfaction of seeing the real thing.
Breathing harder now, Sideswipe shifted his hips and moved faster, harder, sending Sunstreaker's mewls and moans up another level. he kept his eyes open even as her's shut, drinking in the sight of her face abandoned to pleasure and the heat of her against him. Across their bond the cycle of ecstacy richocheted back and forth, minds entwining so deeply that soon they began to forget where one began and one ended. Was it Sideswipe thrusting into Sunstreaker? Or Sunstreaker into Sideswipe. Was it his hair that swept down against his back, or her hands digging nails into curved hips? It was impossible to tell.
Unfortunately, all good things had to come to an end. It was a faded echo of the cruelty of leaving the womb when their pleasure hit its peak and they both tumbled down to the floor, breathing hard and clutching desperately at each other as the intense proximity of themselves started to unravel. Their minds pulsed with a burning afterglow but already they mourned as second by second, they crept back to the less satisfying base connection they shared.
"'Sides..." Sunstreaker closed her eyes for a moment, before reaching over to take his hand in his own, squeezing it in comfort. The dark haired twin smirked in reply, enjoying the sight of his normally vain sister plastered in her own sweat, it was deeply attractive - though he took care not to say it. He was sure though with their connection she already knew his thoughts on that and didn't like them.
True opposites indeed.
Proudly he grinned, opening his lips, "That was amazing. Too bad old pole-up-the-ass Prowl won't know about it tho-"
As if on cue the two's heads shot up, hearing the approaching sound of footsteps. It was a hurried flurry of movement to get clothes back how they should be, there wasn't much they could do about the state of their bodies though, leaving Sideswipe floundering in panic before a slender (but strong) fist impacted with the side of his face.
"Sunny, you bi-!"
"Fight me, idiot!" She hissed, leaping at him and smacking him back down into the metal floor, drawing her fist back for another punch as the door to the hallway slid open and Sideswipe was left marvelling at her genius. They often fought, physically as well as verbally, it was a hurried excuse, but a viable one.
That said he let out a battle cry and went to shove her violently off just as those footsteps began to thunder towards them and hands yanked them both to their feet and away from each other.
"You fragging pit-spawn! You're supposed to be on punishment detail, not rolling around the floor fighting like a pair of hungry cyber-wolves!" Ironhide's sharp, adopted Southern twang snapped into their ears as he shook them rather violently. "Ain't going to be no saving you from the worst Prowl can dish out this time! Primus knows I could suggest a few ideas to him myself!"
Mustering up an obnoxious grin, Sideswipe piped up at the older mech with a rapidly bruising jaw. "Battle go well, then?"
"Yes Sideswipe." Another voice cut in, this time the tired growl of the Ark's CMO, who was flicking his eyes between the twin's suspiciously. "And the last thing we need to come back to is you both trying to offline each other before the Decepticons can. Frag it Ironhide stop shaking them like that!"
"They ain't sparklings, they need discipline..." Ironhide grumbled, but in the face of a exhausted and stressed out medic who had patients to get to, relinquished his grip on their necks. "Slag it, Sunstreaker girl, make yourself decent."
Sideswipe rubbed the back of his neck and quirked a curious brow Sunstreaker's way, realising the improvised fight had made her skirt ride up. He laughed as she hurriedly shoved it back down with an uncharacteristic flush. "Weeeell, we wouldn't want to bother you now, I'm sure you're both tired and have better things to do, so we'll be going!" Reaching over he grabbed Sunstreaker's tanned arm and started pulling her away from the two older mech's. Ratchet's suspicious glare particuarly.
"Prowl'll be hearing about this you two! Don't think you're getting off free!" Ironhide bellowed after them, earning himself another glare from the CMO and a shove as said medic pushed his way past him to get to the medbay.
Thankfully a quick dash through the door saved the twins any further embarassment. They darted through the corridors, not stopping until they reached the relative safety of their own room and were free to collapse tiredly down onto the berth.
"Frag it, Sideswipe. You said they wouldn't be back for another few cycles!"
"Well forgive me, Sunny dear, they obviously managed to bypass traffic!"
"Don't call me that!" She snapped, shoving him roughly and glowering at the opposite wall as if it had committed some grave offence against her. "Frag... that..."
"That was too close." He finished for her, slumping forward and placing his face in his hands. "But its alright, no one suspected-"
"Did you see Ratchet's face?! I swear that sourpuss know's more than he's letting on! I've told you before, he's-"
"Got nothing, Sunny." Sideswipe cut in swiftly before she could go off on a tangent, lifting his head up. "Its alright, honestly. They don't know anything, nothing's going to happen. We just... won't repeat that excercise in the future."
To his credit he didn't even quail at her unconvinced glare, outwardly anyway. Instead he reached over, wrapping his arm around her and pulling her against him. "Trust me, Sunstreaker, it'll be okay. No one's taking you away from me, or vice versa."
"Glitch, that's the same thing." She muttered, but seemed to relax minutely anyway, head dropping onto his shoulder. "Slag, I need to hit the wash racks." Her nose wrinkled in distaste as she sent the uncomfortable feeling of sweat drying on her skin across to him, causing him to let loose a bark of laughter.
"Yeah, yeah, Sunshine. Anything you say. Gotta admit though..." His look turned sly, "That was kind of fun."
"Yeah... but if we ever come that close to being caught again, I'll kill you myself."
"Heh... love you too, Sunshine."
Yeah, it was always worth it. Despite the eternal fear, as long as they had each other.