Reason 1; Company

She didn't know why she did it. Not when she first set optics on him, not when she was pulling him into the darkness, and certainly not now with him propped up on the rocks right beside her. She would have asked him herself what had compelled her if he had the capacity to speak through his pained, ragged cycles of air. Reasoning that it felt 'right' didn't satisfy her. Since when had she ever done anything 'right'? What was right? Who was it that set the moral horizons for every decision that flashed through the processor? Autobots liked to think themselves as on the moral high ground, surrounded by a treacherous sea of Decepticon filth.

A Decepticon with morals. Hmph. That would be the day.

But really, anything could happen when the last of the Primes was dying on her doorstep.

She first saw him buried under the rubble that she eventually learned was the smoking ruins of the Autobot base. The stasis pod that held her captive was melted right through from the heat of the fire all around, and she stumbled out to see him trapped under the seared metal and fallen rocks. How that brief reunion of Autobot and Decepticon escalated to her hauling him out of the debris and into a not-so-cosy looking cave conveniently nearby was another thing she'd never know.

Just klicks after she had dragged them both into the shelter, Megatron's voice rang clear through the chaotic cacophony of destruction that was happily taking up every inch of the airwaves. Angry, but since when was he ever not? Probably having trouble hefting up the rocks with those ancient joints of his in his search for Prime's body. She almost felt sorry for him, so close yet so far from his mortal enemy. Said mortal enemy was making some uncomfortably loud noises though, and she'd be damned if she let Prime ruin her most recent taste of freedom from the Decepticons. She shifted herself over to him, hovering a hand over his groaning faceplate and debating over manually gagging him or just knocking him into stasis and being done with it. But even with her less-than-noble contemplations her optics settled on his own - sparking and lodged with shards of metal. Ouch. Well, at lest she knew why he was making such an agonised racket.

"W-who... are you?" His sudden question surprised her, making her flinch away from him as his ruined optics whirred painfully, desperately glancing around with no clear direction. Her defensively raised servos lowered though at the new revelation- he was blinded. Temporarily, but still blinded. He wouldn't know if his rescuer was Autobot or Decepticon... that would have been useful if she wasn't certain that he'd recognise her voice instantly if she tried to use it.

It wasn't often that one had to shut up a Prime. As such, there wasn't exactly many obvious options available to her. In the heat of the frenzied moment, spark almost pulsing out of its chamber in panic, something hideously primitive emerged from the deeper part of her processor. A dreaded 'femme' protocol.

Her lips touched down on his helm before she could veer herself away, a servo caressing his cheek while the other placed itself beside him. Her optics widened in subconscious protest, and she had to stop herself from tearing away from him, lest the entire gesture be ruined. Well, that was one way to keep them quiet.

A scream of primal rage managed to push her mind off of the deadly 'did I really just do that?' path, helm turning to the source of the sound outside. Oh Megatron, you poor motherfragger. There was something about the thought of Megatron's scowl that set a rare smile on her faceplates. A smile that refused to falter even when she finally heard the Decepticons flying off away from the site of destruction, Megatron's perpetual growl that rumbled through the very ground she sat on departing with them.

Night was falling quickly at the mouth of the cave, dark fingers crawling along the rock floor and grasping at her frame. Unsettling, to say the least. And with everything that had happened that day, she felt that she had earned the right to act like a sparkling if she so wished. Pressing herself against the cave walls only gave her several more klicks of false safety before the night caught up with her again. To add insult to several injuries, Prime was groaning again. Asking the same question out to no-one. She reached over again and stroked a servo along his faceplate, kissing his forehead and pulling herself into him. Even in his decrepit state he emitted an unrivalled warmth in the spreading cold of the night, blanketing her in heat and drawing her in. It was... nice. Strangely nice. She didn't like it- didn't dare admit that she liked it. Even though she had just admitted it then. Scrap. And that's when the second most annoying question of the day reared its ugly helm again; Why did she save a Prime?

As her servos wrapped around his chassis, she eventually settled that company was a good enough reason to answer that.

xx

Reason 2; Convenience

She awoke to blinding silence and suffocating warmth. Primus, he was a heavyweight. As she hefted him off of her a waking groan echoed through the the reverb she could sense pain, confusion and... hunger. Great. Lesson number two; how to feed a Prime.

Through the sunlight slit opening of the cave she could see the bulk of Darkmount in the distance, the Nemesis docked at one side and fusion cannons mounted all around challenging the new rays of the rising sun. Megatron's shiny new toy in all its dispensable glory.

She took a glance back at Optimus, who was suppressing his groan now as he slumped against the rocks. From his sparking optics a whining fizzle set her spark on a dangerous edge- for some reason. So his optics were live fuses waiting to burst, why should she care? But... she did. As simple and mundane as that. Something in her processor told- commanded- her to care. That same something also made her wrap the freshly weaved silk strands in her hands carefully around his optics, the cool webbing dulling the painful, sharp charges of electricity that Optimus had suffered through all night. That would stave off rust, she rationalised. The extra wad of webbing that she set behind his helm... just something to stop him from running off in a literally blind panic.

"Who are you?" His repeated, steady question shot into her backstrut just as she was making to leave. With a weary sigh that she hoped he would mistake for one of apology she grazed her lips along his helm again, rounding at his left audio. The light, warm cycle of air that blew against it seemed to be answer enough for him.

'I'm wondering what the frag I'm doing,' she muttered as she stepped into the wash of morning ahead, and set out to steal from the steel devil that had gotten her into this frustrating disaster waiting to happen.

Any solo Autobot would have found infiltrating Darkmount, or any Decepticon fortress, near impossible. But she hadn't spent millennia with the brutes just sharpening her claws on their chassis- at the base of things, all Decepticons thought alike. That is to say, they were sneaky by creed and underhand by nature. That translated to irregular but scattered guard shifts and patrols. She had pilfered from energon stores enough in the past to know the intricacies of the crime; avoiding guards, unlocking the vaults, and getting the product out, all while undetected. From the ease in which she slipped in and out with two cubes stuffed into her servos, Megatron obviously didn't see any threat to his rations. And if she kept her heists low key, it should stay that way.

She returned to the mouth of the cave just as the ground was bleeding out the last of the evening's light, approaching Optimus silently and setting the glowing cubes down. He was still, apart from the modulations of his chest and the twitching of his lips. At some point in her absence he had fallen into the vice of sleep. She used a talon to slice open one of the cubes, swirling the thick cyan liquid within just as Optimus suddenly jerked upright.

"ELITA!" His call into the darkness stopped her servo as it made to bring the edge of the cube to his lips, and her spark was edged with a faint agony at his cry. 'What is he saying...' She wondered half-heartedly as she tried to ignore the pain at her heart, not wanting to think about what, or who, an 'Elita' was as she gently lay his helm back on the cushion of webbing. His mouth opened and closed erratically, mirroring the pulsing of his spark. He gulped down the energon as it met his lips, drinking in her help without a word. Optimus was asleep again as soon as the last dregs of liquid ran into him, and only when she heard the rumble of his snoring engines did she sip from the other cube. She wasn't thirsty, but she still drank, for convenience's sake. She wasn't tired, but she still aligned her servos around him as her optics shuttered, for convenience's sake. She didn't care, but she still felt her spark ache. For convenience's sake.

Telling herself that over and over was all that stopped her from burrowing into him.

xx

Reason 3; Compassion

The days blended together into a blurred mess of stolen and spilt energon, nights marked only by the burning light of the fires that she set alight when the sun went down. Of course there were close calls- Eradicons catching sight of a leg here, the glow of an optic there, once she even had to slink past Soundwave before she could reach one of the vaults, but otherwise the Decepticons showed no sign of sensing foul play. His sleep pattern was reminiscent of Decepticon guard shifts. Sometimes he slept through the whole day, others he awoke in the middle of the night with the cry of 'Elita' on his lips and her spark was plagued with pain at every residual mutter that passed through his vocaliser. He still sometimes asked for her name, but the usual kiss on the helm kept the curiosity subdued. It wasn't uncommon that she'd find herself cradling his helm as he drifted back to sleep after his nightmares, lips pressed to the guaze shielding his healing optics in a tender lullaby. She didn't wonder why she was so... motherly to him anymore. By now her processor wouldn't allow such contemplations. There was no room for wanton questions of 'why' in the new world that she'd built for herself.

A world that was very close to collapsing.

She realised this when she heard the faint echoes deep within the cave, where she had managed to drag Optimus to. The Prime was in a sleeping spell, and she watched over him while sipping energon and watching the orb of the moon outside. Her optics flicked away from the sight to where she heard the disturbance, and she crept into the darker depths of the cave as she pressed an audio to a rock face.

"Go deeper, soldiers; if Optimus is here, he will have hid himself with utmost care."

"What is happening?"

Optimus mumbled question came as a hand closed over her mouth in shocked realisation. 'The Autobots... scrap, they're determined.' Determined, and very close by, from the sound of Ultra Magnus' voice through the stones. If they found some way into this crevice, they'd kill her without a second thought. Especially if the first thing they saw was Optimus scarred and blinded.

Blinded...

She didn't know how long had past since the injury to his optics, but the worrying fizz that they emitted had since ceased a long while ago. They might even be completely healed underneath the frayed silk wrapping.

She hesitantly spaced her talons on the web strands and slowly unravelled them from his optics, staying at his side as the gauze peeled off. But even before he could attempt to shutter them, she closed her palms over them, and brought her mouth to an audio.

"Your friends are here, and I must leave you now." Her whisper was cracked with a tone of loss that she didn't have the heart to address with her usual spite. "I ask for only one thing in return: don't open your optics until I've gone." He said nothing to her request, nodding reluctantly as she brought her lips to his for the first and last time in their union together. The hands removed themselves, but Optimus obligingly kept them closed until he was sure he heard her departure fade into the distance. The first thing he saw was a blurred, laughing faceplate staring down at him, and a small hand stretched to help him up.

"You look as if you've seen a ghost," Ratchet commented breathlessly as he embraced his old friend. Optimus' heavy servos patted him in return as his optics struggled to take in the shapes of the other Autobots assembled around him. Even Ultra Magnus bore a small smile at the sight of the Prime alive and mostly well, apart from the scratches that marred his paint. With the Autobots each taking turns to express their relief at Optimus' survival though, he couldn't tear himself away from staring into the distance, beyond the cave entrance.

'Not seen a ghost... heard one...'

Even after so many centuries he recognised that voice. The subtle tenor and rich underlying harmony weaved in with such compassion... He almost forgot that his Elita One was long ago lost and buried.

In the mountains, far from the heartfelt Autobot reunion, Airachnid stood alone on a precipice of rock with a hand over her spark chamber.

xx

Reason 4; Conscience

"Even after all of this, after everything, you still think we should spare them?" Optimus made no sign of acknowledging Ratchet's question, opting to keep his helm low and optics pointed lower. It was a habit that he'd developed ever since his optics finally onlined again.

"You know my stance on the termination of any Cybertronian, regardless of faction," Optimus replied after a long silence, lifting his optics to the achingly familiar scene spread out before him. They stood atop a small hill overlooking a barren, scorched field. In the near distance the smouldering remains of the Decepticon stronghold still sent fingers of smoke into the air, the only clouds in the otherwise clear blue sky. The sun shone a spotlight onto the centre of the field, where a line of cannons were assembled, manned by human military personnel. Another gathering of humans and Ultra Magnus trained their guns on their captives- the defeated Decepticons cuffed, chained and cornered like cattle ready for the slaughterhouse. Their leader had been killed first in the collapse of his fortress, saving the humans a round of bullets.

In their hands they held the sparks of gods, and all they worried about was cleaning up afterwards.

"But as fellow victims of a war they never asked for, Earth's superiors deserve to choose how their former captors be punished." Ratchet huffed sceptically at Optimus reasoning, but remained as silent as the other Autobots as the first Decepticon- Starscream, in all his whining and screaming pride- was pulled by a scowling Ultra Magnus into the centre of fire, heels dragging in the dust. Only Optimus was solemn in his silence. Even as Starscream fell to his knees, crying to the skies and whatever deity who would think to listen, no-one dared look away as the cannons readied themselves for firing. His pleas were cut off by a volley of chassis-shaking booms, and he fell to the dirt riddled with smoking holes. Behind Prime, Bumblebee whirred at the sight of all the energon spilling from his death wounds, and Ratchet simply sighed. "What a waste..." As Starscream's body was dragged away, Smokescreen looked on the verge of smirking, but he was lucky enough to glance towards a strangely sour looking Optimus, and he thought better of it. Prime pretended not to hear Arcee's bitter mutter of 'good riddance'.

Soundwave was next, as apathetic as ever even in the many faces of death surrounding him. His visor was shattered, exposing his battered face to the world at last- Optimus didn't want to think of which human had smashed the glass in a fit of rage- and he didn't try to hide it. His crimson optics stared straight ahead, foggy and squinting against the glare of the summer sun. Just before the human at the forefront of the execution signalled to fire though, his optics centred on Optimus, meeting with his blue ones. Even through the glass that still stuck to the edges of his visor, Optimus could see the damned smirk that Soundwave bared. It was a smirk that Optimus had seen and known more times than a simple smile- all shown by Decepticons. He hoped that he'd never have to see it again. The upwards turn of the lips, the tiny flash of the denta, the lopsided line of the mouth... it practically jeered at him as he read its meaning as clear as the cloying sky above.

'I know something you don't know.'

Optimus never had a chance to find out what before Soundwave pitched forwards, taking his secret with him to the floor.

Arcee took on a sneer at the sight of Shockwave approaching the field, servos lopsided from the absence of his gun, replaced by still sparking circuits and empty space. The ribbed cable that linked the weapon to his back hung loose in the light wind, dragging along the dirt as he marched into the line of the cannons. His one optic whirred and flexed like a camera sight as the cannons were loaded again, propelling themselves into his chassis and sending him to rejoin with his comrades in the Pit.

Knockout was last, cringing at the manacles and chains scraping across his scratched paint and stumbling on the ground as the humans pulled him forward. He fell to his knees, servos lashed to his torso and helm kept down. The coolant dripping from his optics mixed with the stains of drying energon in the dirt around him. 'Worrying more about his paint than his life,' Bulkhead thought with a hmmph as the telling shots tore through the air, the last Decepticon spark finally extinguished. Optimus never envisioned that it would end like this, on a planet far from home and with only a tiny squadron of fellow Autobots to oversee the extermination of Cybertron's murderers.

At that, Optimus finally let his aching optics flutter closed. Just as the other Autobots were about to move towards him though, Arcee noticed something else happening on the execution field.

"Don't celebrate just yet," she muttered, recognising the long transporter convoy parking itself on the fringe of the field. Optimus' optics snapped open again, seeing a group of humans gathered around it, guns at the ready, while the drivers said something to a kneeling Ultra Magnus. From his perch Optimus saw him nod, and the humans began unloading the convoy. A still mass of black metal was hauled out, wrapped in chains and shoved to the ground. The Autobots assumed their previous stances as Airachnid was moved in front of the cannons, Arcee just holding back a snarl of pure hatred. Her legs jutted out at awkward angles, and her protoform was pale with an evident lack of energon in her systems. She didn't resist at being pushed onto the life-soaked earth, but even if she showed no objection to her death, something in Optimus' spark suddenly cried out at the sight of her treatment. A blossom of... sadness. Only just overtaking the new confusion that laced his processor. Why was he only feeling this for Airachnid, while his spark remained as steel throughout the termination of the other Decepticons? He'd not even felt such anguish at the death of his old friend Megatron, even if he wasn't there to witness his spark go out.

Below him Ultra Magnus sent another nod to the humans at the cannons, and they prepared themselves for one last shot. Airachnid heard the clicks of the weapons being loaded, and raised her helm up towards them. Her optics copied Soundwave's, wandering in a daze before locking onto Optimus, dull pink meeting with sad blue. Her next actions would scar Optimus' processor for the rest of his life.

She smiled.

She whispered, just loud enough his audios to hear.

"Goodbye."

His trapped optics widened at the familiar sound of that voice before the cannons went off.