[PurdueBrad]

Originally Posted by Chief Rum

Film version:

The Fallen was one of seven Primes (the first Transformers), who were all designated to find systems to build Sun Harvesters to create energon, the energy Transformers use to survive. There was only one rule, and that was that the Primes could not build Sun Harvesters in systems that contain life (the SHs destroy the suns and systems). The Fallen chose to ignore this, believing the Transformers were the ultimate race, and built one on Earth. He gathered other similarly minded Transformers (non-Primes) to his side and formed the "Decepticons". That triggered a war between the Decepticons and the Primes. The Primes won, their former brother the Fallen was imprisoned on Cybertron, and the Matrix of Leadership, the tool which activates the Sun Harvester on Earth, was hidden in a tomb composed of the Primes bodies.

Optimus Prime is the last of those Primes. And only a Prime can kill the Fallen. Megatron is the leader of the Decepticons when the Fallen ain't around, but he acknowledges the Fallen as his master. The Decepticons wear a carticature of the Fallen's face as their symbol.

The rest of it delves more into what happens in the movie (some of which I revealed here), and I doubt it's necessary to get further into it and at the same time reveal the movie plot and what not. Just in case anyone wants to see it who hasn't.

That's the version I went with despite much preferring the comic book version. The Fallen here won't have the same kill conditions although it was something I considered. I just felt it overpowered that role to make The Fallen killable by only two characters.