Talar strängt filmkanon ...
När det gäller Primes (per TF wiki):
Eons ago, the AllSpark created thirteen beings, the first Cybertronians, who had the ability to move between dimensions.
According to Jetfire, the Dynasty of Primes was formed by the first Thirteen Cybertronians. These beings could not transform, but they and their transforming descendants possessed powers beyond that of the average Cybertronian.
Men inte alla transformatorer är en "genetisk" efterkommande av Primes. Primes var bara de tretton originalerna som skapades.
They soon realized that the AllSpark's power, though vast, was not infinite, and required the energy of stars to be replenished. Once a nearby star went nova, the AllSpark created a worker race, the Transformers, who would assist the Dynasty in replenishing the AllSpark.
Sentinel Prime var inte en av de ursprungliga tretton. Han var en direkt ättling.
Sentinel Prime was a direct descendant of the first Cybertronian, Primus, and was believed to be the last of the Primes.
I filmkontinuiteten var Optimus Prime ursprungligen namnet "Optimus". Han och Megatron arbetade med Sentinel Prime.
[Optimus] was the humble leader of Cybertron's science division, which studied the AllSpark, and were protected by Lord High Protector Megatron's military.
[Megatron] was once brothers-in-arms with Optimus and a student of Sentinel Prime, appointed to be Cybertron's Protector and commander of its Defense Force.
Men det var mer att Optimus än att möta ögat. Optimus är faktiskt en direkt efterträdare av en av Primes (Prima, att vara specifik).
It was Optimus Prime's ancestor who finally vanquished the Fallen to another dimension in the battle for the Matrix of Leadership, but his orphaned descendant who was hidden away from the Fallen grew up with no knowledge of what he was.
Sentinel Prime berättade Optimus om sina teorier om Prime's lineage
Though Optimus was too humble to accept, not believing Sentinel's claims about his heritage, Megatron overheard their conversation and became jealous of his "brother." Sentinel formulated another plan for Cybertron's future: it would be governed by Optimus's Science Division and Megatron's Defense Force. By having Optimus investigate the remains of the Primes' civilization, it would encourage him to believe in his lineage.
Optimus finner så småningom bevis på att han är en efterträdare till en premiärminister. Det är då att de andra Autobotsna börjar adressera honom som sådan, och han blir känd som "Optimus Prime".
Back at Burthov, he came upon Ratchet, Arcee, and Elita-One scanning the pieces of the other artifacts. Arcee then discovered that the pieces all contained the same symbol on them, and that the same symbol was on Optimus' head. Ratchet declared that the symbol was proof of the Dynasty of Primes, and it indicated Optimus himself was a Prime. Ratchet and the other Autobots began to dub him "Optimus Prime" [snip] Optimus also informed Sentinel of the marking on his head that proved he was right all along: he was a Prime too.
Megatron var inte en direkt efterträdare av en premiärminister. Han var avundsjuk på Optimus.
But Megatron resented his comrade, knowing he was a Prime and therefore Sentinel's favored son.
Optimus och Megatron ledde till och med Cybertron för en tid.
For two generations, Optimus and Megatron ruled Cybertron together. The two personalities created a balance; Prime was fair while Megatron was firm.
I en av serierna bryter Barricade den fjärde väggen och förklarar att de två är inte faktiska "bröder" trots att den ena gäller den andra som en.
However, in the twelfth issue of Titan's Revenge of the Fallen comic, "Barricade" informed readers that Megatron and Optimus weren't related, the term "brother" was just because they'd known each other for so long.
När vi har sammanlagt det här har vi målat bilden som Optimus och Megatron var en gång nära allierade. De arbetade tillsammans under Sentinel för att få fred till Cybertron. Medan Optimus var en efterföljare av en premiär, var Megatron inte. Fortfarande, från år av vänskap och allierade, ansåg de varandra som "bröder" trots att de inte var genetiskt relaterade.