Princess Mari is an adventurer and living legend within the Microverse. On the day Arcturus Rann, son of the revered Lord Dallan and Lady Sepsis Rann, returned home from his 1,000 year journey exploring the far reaches of the Microverse, Mari's parents, the acting king and queen, were slain by the true authority of Homeworld, the tyrant Baron Karza. Mari disguised herself as a puppet while fleeing to join the rebellion, and adopted the name Marionette. Joining Rann, the rogue Insectivorid, Bug, the mighty crown-prince of planet Spartak, Acroyear, and Rann's roboid, Biotron, Mari and her roboid, Microtron became the team called the Micronauts. Under Rann's leadership, they shared many adventures both in the Microverse and traveling across the Spacewall barrier to Earth. Marionette fell in love with Arcturus Rann. Marionette and the Micronauts team ultimately defeated Baron Karza, but not until the Baron enacted a complete genocide across all of Homeworld. Mari and the Micronauts ultimately sacrificed their lives becoming Prime Beings, seeding life across Homeworld and restoring the planet to its natural state.
Through unrevealed means, Marionette, Rann, and Bug have been reborn, and continue to share adventures together as the Microns.