Marchion Ro was the name assumed by a humanoid male who held the title of Eye of the Nihil during the High Republic Era. Like his father, who held the position of Eye before him, Ro was the leading member of the Nihil marauder group. Because of Ro, the Nihil grew to be a significant threat to the Jedi Order and the Galactic Republic in the galaxy, and the raiders came to revolve around him. During the High Republic Era, he communicated with spies in the Republic to learn of their next moves. Ro also manipulated the Nihil into doing multiple missions so as to achieve his own goals.

Around 232 BBY, Ro deployed a ship in hyperspace to intercept a freighter known as the Legacy Run. His actions resulted in an event in which several fragments of the freighter emerged out of hyperspace and collided with various astronomical objects in realspace. Following the event, Ro tasked his Tempest Runners with conducting various missions, but hid their true nature from the Nihil. When two of the Tempest Runners failed their respective missions, Ro asked one of them, Kassav Milliko, to intercept a transport carrying the Legacy Run‘s flight recorder in the Kur Nebula. Unbeknownst to Milliko, Ro sent the Weequay and his Tempest to their deaths in the subsequent Battle of Kur.

Ro also tasked the other Tempest Runner, Lourna Dee, with kidnapping a family, residing on the planet Elphrona, to be used in ransom, but hid the fact that he sent the Twi’lek there to attract the attention of the Jedi and potentially capture one of them. When Dee and her Tempest successfully captured Jedi Master Loden Greatstorm, Ro informed the latter that he had plans for the captive Jedi in the future.

Ro later sought an individual known as Elder Tromak, wishing to learn about the location of the two halves of an ancient relic. His journey took him to Trymant IV and Quantxi, before finding one piece of the relic on Vrant Tarnum.