A fellow prisoner of Ruon Tarka who built a machine meant to carry them to a peaceful parallel universe.
Oros is a friend Ruon Tarka made while both were held prisoner, revealed in The Galactic Barrier. Tarka explains that Oros built a machine to transport them to a peaceful parallel universe, but the two were separated during their escape, and Tarka never learned whether Oros succeeded.
The hope of reuniting with Oros drives Tarka's actions. He has built his own version of the machine, which needs an enormous amount of power, and he plans to take that power from the source behind the Dark Matter Anomaly.