Fluxpark was a dangerous Decepticon criminal who possesed the ability to travel through time. He was being held in forced stasis lock abord an Autobot prison ship in the early years of the Great War, when it came under attack from a Decepticon strike force. In the ensuing confusion the power to Flux's cell was cut, enabling him to make his escape. With their security forces tied up with the attackers the only Autobot to notice him escape was his personal warden, and intial captor, Capasitron. Flux stole a shuttle and, dodging attacks from both sides, managed to escape into deep space.
Unfortunately for him, the shuttle didn't have a large energon stock, so he powered down all the systems leaving him to drift through space. He once again went into stasis lock, programming the on board computer to awaken him once the shuttlecame close to a suitable planet. He remained this way for almost 4 million years before the shuttle fell into orbit around the planet Earth in the year 1985. Sensing an interesting time signature emminating from the planet, Flux traced it back to its source. He touched down somewhere in California, near a town called Hill Valley. Here he encountered the source of the signature, a crude steam-powered time craft in the shape of a Rogers steam locomotive. Struck by curiosity at how such a primitive race could develop time craft, he scanned the locomotive, at the same time taking it as his alternate mode. After concluding that the vessel posed no threat to him he went to destroy it, however he was interrupted by the arrival of his old warden Capasitron. The two briefly fought before Flux escaped into the past, setting in motion a long pursuit through time itself.
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I am a NERD, end of story. Yes this is some bizarre crossover between Back to the Future and Transformers. Actually my intention is to keep the two storylines seperate, I just wanted an explantation for the two robot's alt modes (Capasitron being the time travelling Delorean). Maybe you could say they both briefly entered another dimension, before returning to their own. I dunno, you probably didn't read all that anyway.