I.

Optimus lurched sideways, nearly falling to his knees as the wave of dizziness hit. There was a wall to one side and he grabbed it to steady his queasily roiling frame. His helm felt so heavy he wanted nothing more than put it down and recharge until Ratchet could fix whatever was wrong with it… and him. Too bad they were in the midst of the battle and Megatron could exploit his sudden dizziness with a blow at any klik, so Optimus tried to collect himself and stand up straight. He stared at the wall that crumbled in his grip, a concrete beam bending like it was cheap plastic, the dust of the cement covering his servo and making his vents sputter in irritated indignation. He couldn't remember being able to break reinforced concrete just like that. And why was his helm so… heavy and restricting… and why couldn't he see properly?

Optimus turned that too-heavy, unwieldy helm from side to side to see whether Megatron was following up his earlier attack but his optics were not cooperating with him. It was far too early in the battle for the warlord to call a retreat so he must be somewhere around. He tried to shake his helm in hopes of clearing his strangely uncooperative processor, but the movement felt like an exercise in futility with how heavy it was, how big, how the open air… what? Optimus wasn't used to feeling air on his faceplates, he was using his mask nearly all the time these vorns and certainly never opening it in a battle! But he couldn't find the protocols to close it, they have somehow disappeared along with the safety of the plate. But there was no pain telling him that it was torn or removed, nothing. Like it never existed.

I must have received a stronger blow than I remember…

Optimus collected fleeing thoughts and reordered the chaotic threads in his meta. Pedes felt heavy and enlarged for some reason, in fact his whole leg assembly was at least twice the weight he was used to. Helm too as he had already realized. Right arm, the one grabbing the crumbling wall… not only heavy, but registering nearly thrice of the diameter he remembered and cumbersome like it didn't even belong to him, like it was a useless, heavy, thrumming and smoldering hot something he could hardly lift, much less swing if Megatron decided it was high time to attack and decide their fight.

Which, come to think of it was surprisingly late to come. Optimus felt like he was dizzily standing there leaning heavily onto the wall and trying to collect his errant wits for breems – certainly more time than Megatron usually took to exploit his perceived weaknesses. So why was a hit not coming while he couldn't counter it? The standard noise of the battle filtered into his audials like they were coming through a layer of cotton, though why would he or anymech else would smother his audials in organic material he would never know, but that was how humans described a sensation to him once and the expression felt strangely but aptly fitting now.

The world still wavered a bit but started to clear up slowly, like fog dissipating from the air and Optimus felt more steady on those still-too-heavy and still-too-big pedes. Optics tried to focus, the delicate mechanisms moving the lenses in and out, rotating the leafs of the shutter in a heroic effort to see. Megatron's silver plating was nowhere to be seen and he ex-vented a tiny sigh of relief, lifting a servo to his helm to try and find the errant mask he keenly missed… and he promptly yelled out as the unexpectedly big something clanged into his helm, only it came out more like a howl at the sudden pain of a dent and Optimus suddenly didn't know which shocked him more, the sound he produced or the hit he dealt to himself.

I don't even need Megatron to knock myself out…?

But why was he so clumsy all of a sudden? Or rather… why was his arm so big? Optimus lifted the arm again, slower this time with more care and stared at it incomprehensively. It just… made no sense whatsoever. None at all to have Megatron's cannon on it. At least he knew now why he clanged it into his helm. But his subprocessor insisted that it wasn't somemech else's cannon, it was HIS. It unhelpfully loaded the targeting system too to prove it. It overlaid his HUD and started to label mechs around him with targeting ratios, percentages of probable damage, evaluation of threats… and why was there a separate subroutine that had no other job but track Starscream as a particularly dangerous target?

The uncomfortable – and heavy – truth started to settle in his processor. All the anomalies, all the differences, the strangeness… and the cannon sealed it, proved it in a way hardly anything else could. Optimus looked down with clear optics now, noting the reddish tint of his own gaze, but dismissing it for more important matters… yes, his frame was grey and black, silvery and stark metal, pitted and scratched and much thicker than his own; heavy, safe plates of a gladiator-armour, unlike his reinforced civilian one, the large, strong pieces interconnected and overlapped for maximum protection, the powerful power-plant idling beneath comfortably but perfectly able to power strong and thick-plated limbs for devastating blows… as he well knew from the receiving end.

So… I am in Megatron's frame. How curious.

But he had no time for shock and if he was in the warlord's frame, then where was his? The helm was starting to bother Optimus. It was not only incredibly heavy and unwieldy, but very restrictive too, he could barely see to the sides, his audials still felt like muffled, even though he did hear the battlefield noises perfectly well and the targeting software appeared to have a processor of its own, requiring him to emphatically deny firing the cannon every few kliks or so. Still, he tried to swing the heavy helm left and right, scanning the chaotic battlefield that not only had a lot of smoke and dust to make visibility nearly zero, but also it was overlaid by a tactical layer similar to his own, but the complexity of it shocked Optimus greatly. It was obviously a close-quarter fighting one – no wonder Megatron preferred to wade into a battle instead of orchestrating it from the back lines – and it had incredibly details and threat analysis of every mech near enough to be considered one. And it suddenly zeroed in on a particular frame, not far from him, lighting up in purple like a mad fireworks display…

Oh, for Primus's sake…

Optimus ground sharp dentae he was afraid to label as fangs, growled, shocked himself with the sound but managed to shut down his cannon completely, forcing his will over insistent software and energon-thirsty protocols. He did not want to accidentally shoot his own frame which the cannon all-too eagerly wanted to do. He had never known Megatron acted so much on preprogrammed impulses and set protocols. No wonder the mech appeared to never listen to reason – by the time arguments arrived to his processor he would have already attacked. His frame – Optimus's frame! - appeared to be even more shaky and hesitant than himself – if his guess was right and Megatron was in it, he appeared to have even more trouble adjusting to it than Optimus.

Let's not talk about poetic justice…

His processor by this time felt clear enough so Optimus could forcefully shut down most of the irritating tactical display and have a real look around the battlefield. He was dismayed enough to realize that the whole exchange and adjustment took no more than two kliks and nomech else on the battlefield appeared to have noted the change. Most mechs were still fighting their own battles as per the usual choreography. That meant he might get hit by any of his own overenthusiastic Autobots trying to 'save' him… umm, his frame which now probably contained Megatron. He did rather look like standing over a fallen enemy victoriously, his dizziness and shock probably not showing outwardly.

I should do something about it…

But he still didn't feel all that comfortable in the warlord's too-big, too-strong, too-eager frame to do much. Coordinated movement was a guess at best, judging from the way he nearly knocked himself out just a klik ago. Optimus quickly dropped the remains of the reinforced concrete beam from his servo sheepishly, hoping that nomech noticed him hitting himself in the helm with it, and thought furiously, trying to find a way out of this predicament. Comms! The brilliant idea came suddenly and he automatically opened a channel to his Second.

"Lord Megatron?"

Umm, no, no, no, not that one.

Optimus shut down the channel hurriedly with the emotionless tone of Soundwave and tried to consciously remember the Autobot frequencies. It sometimes helped to have a paranoid security director, as he forced them to change codes every decaorn and learn them by spark… yes! He remembered the correct one.

"Prowl?"

"…"

He would have to record somehow how a thoroughly shocked silence sounded from the Praxian. It wasn't all that often he was left speechless, but apparently the enemy's commander contacting him in the midst of the battle was enough.

"It's me, Prowl, Optimus Prime. I… we… appear to have exchanged frames with… umm, Megatron."

"…"

I hope he didn't glitch.

Optimus turned, turned back again and found the black and white frame where he remembered him to be – the opposite side of the battlefield of course, he himself was where Megatron used to stand, so facing his Autobots, have to remember that – and waved a friendly servo in the air – the one without the cannon, the one he felt he could lift comfortably and not hit himself in the helm again, and hopefully meaning less threat than the outrageously be-cannon-ed one.

"Lord… Optimus Prime? What?"

"Now, Prowl, no need to Lord me." – for Primus's sake, where did that wretched bit of humor come from right now and why? – "I mean, it is really me in his… Megatron's frame. Somehow."

"Sir…" – Prowl straightened up and Optimus's targeting software nearly crowed in glee, finding another so important target and Optimus gnashed his denta in an effort to shunt it back down in the Pit. He so didn't need this! – "Please, Sir, call a ceasefire… if it is really you?"

Yes, that is a good idea.

But Optimus suddenly had other problems than convincing Prowl. His tactical display roared at him to FIGHTFIGHTFIGHT as Optimus, umm, his own frame with Megatron probably in it stood up, still tottering on unsteady legs and holding his helm in his servos - and his frame was moving under its own initiative and Optimus was horrified to see a silvery arm swinging around for a hit that would surely take out himself – with Megatron and all – and it was becoming extremely confusing for a klik, dizziness again swamping him as his main processor and his tactical subprocessor got into an argument about who was who, who was the enemy and was it not a god idea to shut down Megatron even if it meant damage to his own frame?

He might have the same conflict, causing him to be dizzy still.

The arm's arc completed, his blow connected to the blue helm and Optimus felt a pang of something indescribable as his… Megatron's… the blue helm snapped to the side – there was something for thick and heavy helms, Optimus conceded sullenly, he would never change his own headwear, but the blow knocked him… his frame out all too easily and Megatron fell back to the ground in a heap.

Damn.

"Cease hostilities NOW!"

Well, that might not have been the way Megatron would have expressed the order, judging from the Decepticon helms that swung towards him surprised, but at least they obeyed the order at once. There was something for tyrannical warlords too who didn't allow questioning their words. Optimus saw Prowl stand up fully and noted the rising brow of surprise mixed with worry for what he still saw as his leader downed. Ratchet and the twins guarding him were already moving towards them, unafraid for the threat he represented, the medic's single-minded focus on his damaged leader, the twins' on their medic, daring anymech to pose a threat to him. Even if Prowl decided to tell them what happened, they shouldn't believe him – and Optimus – so fast.

They didn't. Approaching with drawn weapons and suspicious glances they got closer and closer to their strange duo. But then of course things just got even more complicated than that… Optimus nearly cursed when his tactical display once again went haywire and screamed flashing purple alerts at him. Since the Decepticons were still just standing around uncomprehending Optimus at first didn't get it…

… then the slender, tricoloured frame swooping down by him explained it adequately.

"Starscream."

He wasn't even surprised to find the cannon turning itself on again and being trained on the approaching Seeker. The tactical display marked him as just slightly less of a threat than the Prime – himself. Optimus debated himself a bit whether to take that as an insult, but in the end considered it ludicrous. Who was he to judge the level and seriousness of Decepticon infighting?

"Mighty Megatron… might I enquire why did we stop the battle?"

Uhh-ohh… the Seeker seemed to be furious under the honeyed tones of his question. Optimus was surprised just how easily he read that out of the angle of those wings. His servos twitched in an unidentified motion. Unfortunately he noticed Soundwave getting closer too and his emotionless mask was disapproving as well. It might be that his unintended subterfuge was coming to an end… or it should be, really. Optimus wasn't sure he could convincingly play the warlord's part long term or if he even wanted to. With two suspicious lieutenants? Forget it.

"Everymech stop! Back!"

This time Optimus was glad to have an eagerly humming fusion cannon to back up his order.

"Starscream!"

He swung the business end with its smoldering pink energies towards the sneakily approaching Seeker and started to agree with the tactical display's assessment of him. The jet was sneaky and dangerous.

"Stand down! Prowl! A ceasefire while we discuss this?"

Prowl stood a cautious distance from him, but nodded, despite of the loudly rising disagreements from the rest of the Autobots. The situation was clearly sliding out of control – and sanity.

Optimus have had enough.

"Enough! I am Optimus Prime and that is Megatron in my frame there. Something exchanged us and I intend to fix it soonest!"

He kept an optic on Starscream and sure enough he caught the interested-eager-calculating glint in it at the declaration. The rest of the Autobots and Decepticons reacted with the expected mixture of disbelief and doubt, leaning to demands for proof from the braver mechs. A tiny, barely there touch in his processor told him that Soundwave preferred to gain first-servo evidence instead of useless questions. Optimus tightened his mental defences, but let the telepath touch the surface and gain his proof. When the masked helm nodded, many Cons fell silent. What took the telepath to be convinced was enough for many and for this Optimus felt a bit relieved. His Autobots might take a bit more to persuade of his authenticity, what with himself being in Megatron's feared frame, but Prowl seemed to accept his word and it too helped.

"Ceasefire: suggested. Exchange back: necessary. Research: needed."

Prowl nodded to Soundwave but his optics sought out Optimus's own frame, still lying on the ground. Optimus hoped that he didn't damage himself too much with that hit. It was necessary at the time – considering Megatron's usual temperament and his neglecting of any shreds of common sense in simple situations – but it was a problem now. He was compromised too, to say at least. He should entrust the negotiations to Prowl and Soundwave.

"I suggest our science team for the task. I offer safe passage for… Lord Megatron… in any frame until we can reverse the effect."

But that had the uncomfortable complication of Starscream being… well, Starscream. The Decepticon SIC.

"What? No! You won't take him as hostage!"

It was clear that Starscream himself wasn't sure which Megatron he was talking about. The frame with its threatening fusion cannon? Or the still unknown of the real Megatron is the Prime's frame? He only knew that if anymech messed with Megatron he would want to see it. Or do it himself.

"We are both hostages in each other's frame, Starscream. I wouldn't harm myself and I would hope Megatron wouldn't either. So unless you have a solution…"

"I want to be there!"

Of course… Optimus remembered that the Seeker used to be a scientist before becoming a backstabbing SIC in the Decepticon army. Well… he could keep a few optics on the Seeker to not to do any funny business. It pleased his tactical subrutines to no end.

What an orn…!

"Decepticons: retreat."

Optimus opened his mouth to echo the sentiment but Prowl was faster ordering it – and thereby politely reminding his leader that while in Megatron's frame he shouldn't give orders to the Autobots.

Well. Better remember that.

The Decepticons transformed and flew away uneasily after Soundwave, leaving the Autobots, and the slyly smirking Starscream who apparently started to enjoy the situation, standing around. Ratchet knelt by Optimus's frame to check his vital signs and pronounced him to be fine, just temporarily out. Optimus sighed an exvent of relief. The situation was still tense but tempers started to calm down and mechs folded down to their alt-modes to get back to the Ark, uneasily avoiding the silver frame in the middle. Optimus, too initiated his transformation sequence, intending to drive after them while Ratchet took his frame back to the Ark.

The ensuing sensation was… incredible, to put it mildly. The world suddenly exploded and compressed-contorted at the same time making him groan at the wildly incomprehensible sensory input. Starscream, standing not far from him became a giant in the space of a nanoklik, while the ground jumped up to him and hit him hard in the back. Then, before he could utter a sound in shock he lost a good two third of his senses, most of his mass and all of his ability to move.

WHAT IN PRIMUS'S NAME…?

Hearing was what remained most to him, though even more muffled, cottony than before. It brought to him… giggling? Chuckling, guffaws and outright, loud, incomprehensible laughter? Optimus started to freak out. What happened? Has he been exchanged back to his frame? Has Starscream done something to immobilize him? Why were mechs laughing then? Then his now incredibly narrow but sharp tunnel vision found Ratchet and the medic too was… smirking?

"What happened?"

He felt more than saw Starscream's steps come closer and squat down beside him, the scratchy voice vastly amused.

"Now I believe you being Optimus. No way Mighty Megatron would forget his… alt-mode…"

Optimus wanted to facepalm, a motion of course denied to him in this form. Of course… Megatron's alt was a weapon, not a vehicle. His alt now. He considered shooting the Seeker with it between those infuriatingly amused optics. No. That was Megatron's instinct, not his. Still, the remarks and the smirks smarted his pride. He was about to transform back when he felt himself being picked up – and Optimus decided that he definitely did not like it and couldn't imagine how Megatron could stand the action. Who was it?

"So that's the Slagmaker himself… umm, sorry, Optimus, I didn't mean it that way!"

"Ironhide." – Optimus commed him in a tight voice because apparently his vocalizer was stuck in this form as well – "Put. Me. Down."

Starscream's laughter still irked him as he transformed back to stand on two, rather shaky legs again. The world imploded and distorted again, the weight returned to his frame with a vengeance and made his trembling knee-joints buckle and Optimus scowled in displeasure. The half-hidden smirks did not help. His own frame, standing now with a rather groggy Megatron in it and Ratchet's help did a little. He gave a longing little wish for his truck form. How was he supposed to move now? Walk to the Ark?

Half a breem of exciting and lively explanations later, after convincing Megatron to cooperate – as if it wasn't his goal too to return into his frame! - Optimus was lying in that accursedly helpless alt mode again, in his own truck's cabin, which was definitely a first for him, but he couldn't learn to fly that fast. Megatron was shaking in disgust on his tires and his unending angry tirade about the inherent inferiority of the frame he was forced to exist in definitely bored Optimus who couldn't answer anyhow. Starscream was cackling to himself and nearly choking with glee and not helping either manners and tempers. Which was probably why the damn Seeker insisted on staying.

And that was before they realized that Megatron couldn't drive.