The publication of "Transformers: The Ultimate Guide" by Dorling Kindersley cemented this notion. Writer Simon Furman incorporated the various aspects of the Dreamwave comics story, some elements of the Fleer storyline, and his original Marvel Comics origin to create what is now essentially the "definitive" origin for Unicron. In this version of events, Unicron and Primus are again twin heralds, giant metal planetoids created by the "One", who is sent to explore the universe. Unicron is an imperfect being and turns to evil, adapting his form to transform into a giant robot. To battle him, The One gives Primus this power as well, but Primus opts to remain in planet mode. He passes the transforming abilities on to thirteen robots he creates, the first Transformers. One of the thirteen turns on Primus and sides with Unicron, and the war culminates in a battle that sees Unicron and this traitor, the "Fallen", sucked through a black hole into another universe.