The Thirteen are said to be the first Transformers created by Primus, in imitation of Unicron's transformation abilities. Rumored to be huge and powerful like their creator, legend has it that each was designated a Prime, and given an aspect of the multiverse to guide over, as well as manning Primus's physical form -— planet Cybertron. But power corrupts, and many of the Primes betrayed one another -— with one even siding with Unicron —- until few remained, secretly aiding or manipulating the next generations of Transformers.