My beta came up with the awesome summary. Thanks to her!
Warning: This does have The Virus Twins in a sexual (sort of) relationship, so a sort of incest, I suppose, though they are neither human nor living creatures - complete with family - at all. Just so you are appropriately warned.
Two woke what he knew was only moments after his other, stirring comfortably - though he had woken fully and instantly - and recognising the familiar weight of One's gaze on him before he even opened his eyes. Two's thin lips curved in a faint smile as he stretched, turning and pinpointing One's location before he opened his eyes.
One returned the smile with a smirk that matched it almost perfectly, pushing, hips first, away from the wall he had been leaning against and approaching the bed. By his demeanour, an onlooker might assume he hadn't slept, though he was still dressed only in loose, light blue-silver sleeping trousers.
Two sat up, pushing his braids back over his shoulders and arching his back to imitate releasing kinks in his spine. The action made his other's mouth twitch in silent laughter before he settled onto the bed in the space Two left as he crossed his legs.
Two's brows flicked in something that was almost, but not quite, surprise, as his other reached out to him - not hesitantly, they were never hesitant with one another, but with shades of . . . reluctance. Nevertheless, he mirrored the stretch, smoothly entangling his fingers with his other's.
One's lips shifted into a soft smile at the sight of their identical pale flesh sliding together, no friction marring the smooth pleasure of the contact, heightened by the sight of the miniscule, only half-visible sparks of their Code showing through, brighter, as always, where they were touching.
One tugged his other closer to himself, but Two stretched languorously, leaning back just enough to add a flick of distance between them. One looked at his other curiously, not hurt by the withdrawal, just left with wanting and a question - both of which he knew would be quickly answered.
Two tilted his head with equal, but differently-aimed, curiosity, then swept the palm of his free hand over his other's thigh, ignoring - for now - the layer of fine silk that separated their skin, before tracing his fingers up One's bare chest.
One's eyes slid closed, and he moaned almost-silently at the warm pleasure sparked by the touch, as familiar as his own - more so - even with their sleeping trousers between them.
Two felt the vibrations of the appreciative noise fluttering into his hand from his other's chest and echoed it, his eyelids dropping shut as well - but only for a moment.
One stroked his fingers unerringly over the backs of Two's, arching his chest into the contact and pushing his other's hand closer. Two's lips quirked slightly as he allowed the pressure, and then concentrated delicately, skilled fingers triggering the familiar sparking of their Code reflecting between them.
One slid his hand down and clasped it softly around Two's wrist, not pulling his hand away, or even stilling his movements, just reaching for another point of contact. Two made a small purring noise of his own, tightening the weave of his fingers with his other's in reaction.
One actually grinned, eyes opening again, and calculatedly moved his grasping hand from Two's wrist higher up his arm, sliding gracefully even closer to his other, whose eyes dropped to the rumpled sheet and then closed.
Two forced himself to still, allowing his other to play, to lead their dance, despite the rising urge to continue as he had started. One smiled at the obvious offer, his pleasure sliding through into his other's mind as well, freely shared.
One tilted his head, sending his braids cascading roughly over his shoulder blades, with a tiny familiar sound, turning their joined hands over and slipping the hand on Two's arm over his shoulder and behind him.
One tugged his other encouragingly, and Two obeyed the movement easily by shifting forwards, his now-free hand resuming the soft strokes he had abandoned.
Two slid his fingers in a long, spiralling stroke down from One's pectoral, where they had been resting, until the tips were brushing teasingly just at the very edge of the soft trousers.
One twisted his hips up into the light touch, his fingers winding tighter with Two's in reaction. Two moaned silently, stroking his other's fingers with his thumb in a soothing, needy movement of his own. One's eyes closed once more as he pulled his other yet closer.
One and Two moved in tandem, their most perfect symmetry reached only in such moments. They both shifted in towards one another, moving blind, but manoeuvring with no difficulty. In moments they were pressed together from shoulder to hip, small, sparking flickers of their Code flowing back and forth between them easily, only a slight blip, a miniscule, fraction-of-a-second lag at the place where their skin slid smoothly over their other's.
Two curved a hand up and around the strong contours of the place where One's shoulder shifted and traced sinewy lines up into his neck, and felt his other's moaned response to the caress echoing from his own throat.
Two felt his other's mind phasing through their skin-to-skin contact - as much as they could touch of each other without parting to undress - and his own sliding right back until it was hard to separate them from each other - as it had been, so long ago, when they had first been designed.
Two twisted, and One tensed - or was it the other way around? - and their Code ceased to pause at all, flowing freely from one body to the other and back, their minds - their mind - caught in the swirl of it all, of everything they were, they could be, rapturous and glorious, and above all . . . together.
A single Virus in two bodies . . . efficient, deadly and unstoppable - too unstoppable for the Architect to allow, eventually. Over time they had separated further, just a fraction, just enough, but they always came back to each other - to this.
Despite their slowly developed - and very slight - differences, they always remembered being a single mind, being one, and at times they strove to regain that, if only in a fleeting moment.
A perfect harmony of pleasure reverberated through the entwined forms, sparking at their fingers, and One leaned a touch more, just as Two turned, and their lips met. It was hardly chaste, but neither was it deep - anything more was unnecessary, the contact the last link they could make without parting, however briefly.
Code sparked there, brighter than anywhere else on the almost-white expanses of flesh against flesh, and braids dropping and tangling together around shoulders and wedged between chests - every centimetre of their skin flared with awareness at the last distance bridged.
They gave in to the impulse strengthened by the awareness, pushing focus through the nigh-overwhelming sensation to phase and swirling together without even seeming to move - the only thing that could touch them in this form was their other.
The sparks intensified, but they were not so easily visible now - unless you could read Code as easily as they could, and their own was long familiar to them.
That single, smoky twist of their being lasted for what could have been eternities - though they knew they would later remember every second - before the feeling rushed, almost too quickly, to a peak, which flared brightly through every particle of their currently-incorporeal forms.
They collapsed back onto the bed, no longer ghosts, and allowed themselves the indulgence of the very human impulse to pant.
Their hands were still wound together, and One managed a tired sort of smile as his other tightened the grip, stroking his thumb along One's wrist.
Two sighed lightly, curling up on his side, still enjoying the feel of his other's skin against his own, and their hands interwoven, familiar and perfect.
One mirrored the movement, legs sliding along Two's more than was necessary as he settled comfortably in the embrace of his other. Two smiled contentedly, moving to twine their limbs even closer together before allowing his eyes to close again.
One traced the unchangingly familiar lines of his other's face with his gaze before following suit, preparing to rest - this time meshed with his other, as they should be.
One's absent thought slithered through their awareness with pleased familiarity. There was the silent murmuring of an agreement from Two, who was already mostly unaware, and One smiled slightly at the sleepy sensation, then followed his other into sleep with hardly another whisper of thought.
So I didn't have much in the way of characterisation to work with, but I hope they seemed realistic enough. As it were. I started writing this randomly after a prompt generator gave me 'structure'. It didn't make much sense as a title, though, and I hope this one does. . .