Megatronus was one of the original Thirteen Primes created by Primus and the founder of the Decepticons in many storylines. Originally, he was depicted as having betrayed his creator by siding with Primus' dark twin, Unicron. In the final battle between Primus and Unicron, Megatronus fell victim to the same fate as his master, sucked through a black hole into another dimension. However, while Unicron emerged in another universe, the Fallen was not so fortunate, finding himself trapped in the "underspace" between dimensions. This origin has been altered or revised several times, even to the point that Primus and Unicron are removed entirely, even so, this is because he can jump through time and space, and hop dimensions, like the other Thirteen Primes.