The Primus Trilogy is a Transformers fanfic by Dragon Tail on Live Journal.It's set after the Unicron battles. The defeat of Unicron has summoned an enormous Black Hole which is slowly sucking up Cybertron, and the only thing that can stop it are the four Planet Keys. Optimus sends four teams out to the four planets that hold these Planet Keys. Each team has its own side story with its own characters, conflict and chapters. A little in-between story is set between side stories.