AU Chapter 4

Universe 4 is the home of "Zen Buu".
 * During the final battle against Majin Buu, Vegito was absorbed.
 * When Vegito diffused into Goku and Vegeta, the two Saiyans were absorbed by the magical insides of Majin Buu, transforming the monster into potentially the most powerful creature in the universe.
 * Buu proceeded absorbing all other creatures he considered worthy of absorbing.