The Primes have a sacred rule to never deplete a star that sustains life. One Prime violates this rule by building a star harvester on Earth, for which he was defeated by the other six Primes, and becomes "the Fallen", the original Decepticon.
Originally one of the original Primes, the Fallen went rogue when he gave into his greedy ambitions for power, but was thwarted by his brothers and imprisoned for his actions. He later founded the Decepticons through manipulation, becoming the master of Megatron.
Though he could understand his desire, The Fallen himself hungered to return to the wretched planet where his brothers, the Primes had betrayed him. The Fallen also explained that the only threat to him was the last surviving Prime, Optimus.
He was depicted as a member of the Decepticons under the leadership of the Fallen, serving the villain due to being tricked as to believe he was working for Cybertron's benefit. However, when the other Primes confronted the Fallen on Earth, Jetfire realized his mistake and was teleported to an unknown location.
The Fallen is the only Pure Evil Villain from the Aligned Continuity to come from Robots in Disguise: all the other Aligned Pure Evils came from Prime. This is also, alongside his Generation One and live-action incarnations, one of three incarnations of The Fallen to be Pure Evil.
Transformers Movie History: The Fallen Origin | The Story of Megatronus
Is Megatron the fallen?
Thirteen Original Primes
The original Megatronus, better known as the Fallen, was one of the original Thirteen Primes created by Primus. Megatronus betrayed his creator by siding with Primus' dark twin, the malevolent planet-eater Unicron.
Having grown a love for entropy and decay, Megatronus was seduced to evil and become Unicron's servant, turning against his creator and his fellow Primes, in which he is now only called the Fallen and dubbed the First Decepticon, slowly using his mastery over the dark sciences to manipulate his way to bring forth ...
He's got rust in places he didn't even know he had. Basically, Jetfire's old! An ancient Decepticon Seeker, Jetfire was around long before the war broke out, and unlike many, came to see his "comrades" for what they were. This caused him to defect to the Autobots, something virtually unheard of.
When the council approved Orion's ideas they renamed him Optimus Prime and told him he was now leader of all Cybertron. Megatron, furious that he was robbed of his rightful title believed Optimus had used him for a personal power play.
When he was rejected the title of Prime, he decided to rage war on the Cybertron and left it dead and lifeless. Now he fight with his once good friend, Orion Pax over control of of the Human Planet, Earth.
The Fallen is one of the 13 original Primes. All 13 of them are a special and highly powerful Cybertronian. Only they, or one descended of them, can possess the necessary power to be able to kill them in a fight.
Enraged by his brush with death, Megatron became disillusioned with his former pacifist ideals. Now, he was convinced that only power and force could achieve change.
However, he's reformed in some point before the start of the series. He now works with Optimus and his Autobots, as well as G.H.O.S.T., to protect the people of Earth, human and Cybertronian alike. Megatron cares deeply for his former troops, and dislikes G.H.O.S.T.'s treatment of them.
The Fallen are the secret enemy of the Unforgiven -- the present-day Dark Angels and their Successor Chapters who relentlessly pursue their ancient foes in a desperate search for forgiveness for their ancient betrayal of the Emperor. The Fallen's treachery and betrayal is the Dark Angels' secret shame.
In the face of enduring a shocking betrayal from a trusted Decepticon and barely surviving a grave injury in the process, Megatron began evaluating his actions and motives. After Shockwave killed Bumblebee, Megatron surprised everyone by taking the fallen Transformer's insignia and proclaiming himself an Autobot.
When he was introduced, Jetfire explains that he was a decepticon but then switched over to the autobots, because he didn't agree with what the decepticons were like and fought for, saying something along the lines of them being too hateful.
In Revenge of the Fallen, Jetfire seems to be the opposite of the Fallen. For the Fallen, he was one of the Primes before his misanthropy led to his downfall, thus making him form the Decepticons.
See Jetfire (disambiguation), Skyfire (disambiguation). Jetfire is an Autobot and former Decepticon from the Generation 1 continuity family. Science means that not all dreams can come true. Jetfire (aka Skyfire) is a bot of science, literally.
Jetfire is more than a yes-man; he's the crucial link between Prime's role-necessitated distance and his troops. Though professional and businesslike, Jetfire infuses his interactions with a down-to-earth friendliness.
Both he and Tarantulas are the only villains from the Beast Era to be Pure Evil. While Megatron is Pure Evil in the original English dub, in the Japanese dub, he, like the rest of the show, is played for laughs thus he doesn't count in that version.
Wounded, he attempted to stumble away but Optimus Prime came up behind him, punched through his chest and ripped out his spark core with his bare hand before crushing it. Prime then stood back as The Fallen slid to the ground, Energon leaking from his mouth, thus finally killing The Fallen.
When his power is at its height, the Fallen can open space bridges and travel between dimensions and realities at will. In his physical manifestations, the Fallen is truly a terrible sight to behold.
