Orion trains Red Faction members during 'fitness training' for the "Miner Olympics", a front for training the miners for the Red Faction uprising. Among his trainees is Parker who Orion guides him through the training course. Orion is mentioned throughout the game by both Eos and Hendrix but only appeared in person once. After Parker kidnaps Ultor Executive Richard Gryphon, Orion takes Gryphon to the Red Faction base for questioning. Orion survived the attack on the Red Faction base and along with Hendrix and the remaining miners assaulted the mercenary barracks. It is unknown what happened to him after the Earth Defense Force arrived to Mars but it is assumed that he survived the events of the revolution.
Orion is one of the characters mentioned by Parker in Red Faction: Guerrilla. By the events of that game, fifty years after the Revolution, Orion has most likely died.
His name is most likely a psyeudonym chosen to protect his identity (and family) just as Eos uses a psyeudonym.
Depending on whether you play the game on the PC or console, when Orion talks to you in training, he may or may not have a moustache. However, when he is seen in-game, he indeed does have a moustache.