https://www.tumblr.com/luxafers-triak/780094543226863616/ykw-archivist-orion-pax-is-not-gonna-be?source=share
I went ahead of myself
Back to what I was saying before megpax happened
Orion Pax would know so many things about Cybertron itself and its inhabitants that not even Soundwave nor any of the spies themselves know about.
But also I believe that he would be forced to monitor some of the 'sessions' that went on there. That he would told that he was needed to film some things for the Senate only to find himself in the middle of a crime scene (and sometimes having to participate under the threat of whatever)
He would document history as it plays out and has to release the rather heavily censored versions of those events to the Iacon Hall of Records.
I also like to imagine that he would be so much older in this universe. I'm talking alive since the beginning of the Quintesson age of Cybertron, like he was there for the rise of the Quintessons and the end of it (he was part of the regime that killed them and had garnered quite a reputation there).
During that age, he was able to freely document what the Quintessons were doing and are going to do. He was also able to get into meetings where he would translate, make notes, transcribe their conversations, draft treaties, organize events and parties, record certain things, etc. etc.
He was both a highly-valued soldier and Archivist for them. Because of this, he would also be sent on stealth missions, honey trap his victims, do surveillance, basically all of those black/special ops slag.
However, the problem lay in what the Quintessons were doing to some of the other species, specifically Cybertronians. They would treat them like they were worth nothing, starve them if they disobeyed, use them for their own selfish desires, and drain them of their energon just to give them a fraction of the amount the Quintessons received.
Some of the Cybertronians (the Primes and others), however, didn't care enough of the consequences and chose to lead a rebellion against them.
Now, this is where Orion Pax noticed and did not notify the Quintessons of what they were doing. He believed that they were actually doing the right thing to stand up for themselves.
He gave them weapons, more energon, notes of what they were doing in the meetings, and provided healer training (it was rough since he had little to work with, but he gave them the basics whenever they had common injuries. If he could, then he would also provide them with the proper materials for medical supplies).
When the Quintessons eventually found out, he was close to being executed on the spot when the leader of the entire colony approached the scene and commanded that they don't kill OP because they should break him first.
After that, they kept their promise and tried everything they could to do so. They tore his armor apart from his protoform, deprived him of energon and of any form of sensory, used him, basically torturing him until he almost couldn't take it anymore.
But when they suddenly left him alone one cycle because of a meeting being held, he took that chance to escape from where he was being held (in the chambers). It was eventually found out a couple joors later, and they searched every crevice for any sign of him. But, it was too late, and OP was already halfway there to Iacon.
The Primes, while on patrol, found him in the middle of a clearing, stumbling and in a state of constant agony.
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With the help of Orion Pax, who proved to be a competent soldier, they won countless battles.
Originally, after recovering enough to fight, Orion had to go through training and ranks all over again. He quickly rose up the ranks and became one of the leading generals (though this didn't really mean much when they were still in the early stages of the war).
He had all of the soldiers trained in Quintesson combat as he was the only one who knew how to. He himself modified almost of them so that they were able to have very powerful weapons to use against them. He trained the rest of them as medics, mediators, translators, etc.
(A few vorns later because I don't know what else to say in this part, okay)
Even though they didn't really have a chance in the beginning, they ended up winning the war.
In the final battle, they were close to giving up because the Quintessons were overwhelming them when Orion Pax came into the scene.
Orion, who wanted revenge for what they did to him, stormed in with powerful machine guns and blades. It was brutality and bloodlust at its finest.
He absolutely decimated every last Quintesson until they were nothing but a field of hollow corpses. After that, he had left on a spaceship for a couple of chords before returning back.
When he came back and Cybertronian society began to rebuild itself, he was there through all of it.
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Somewhere down the line, some of the Primes turned away from their beliefs and everything else happened.
The caste system was put in place, and everything went to hell afterwards.
The cycle of them turning into oppressors began, and everymech suffered as a result.
The Pits, which was originally friendly sparring, turned into a bloodsport. Iacon, which was a place of fighting and violence, turned into the main source of the oppressive high-caste mechs and architecture. Kaon, once a place of the arts, became too dangerous for once to go alone unless you were born in it. Tarn, known for its beautiful architecture and wildlife, became the source of Cybertron's minerals and had abandoned buildings. Other cities had not yet formed until several vorns down the line.
Orion Pax, who had dreams of living a peaceful life and not surviving yet another horrific cycle on the battlefield, realized that it was all for nothing, now that they were destroying themselves from the inside.
He only wishes for this to end peacefully (in the back of his mind, he only knows that this is wishful thinking).
He meets Megatronus and Soundwave, helps with their cause while also trying not to give anything away from his past (he slips up a couple of times, and it messes with his mind that he can't tell them, no matter how much they insist), and everything else goes almost exactly how it did in canon.