Optimus Prime is the leader of the Autobots and was previously Orion Pax, a laborer on the planet of Cybertron. As Orion, he was a close friend of Megatron and the two began a shared revolution to end inequality which put them on opposite sides of a civil war. Orion became Optimus Prime after he received the Matrix of Leadership, leading the Autobots against the Decepticons in a struggle for the Allspark. Both factions have been on Earth since 1984 and now fight to reform the ancient Emberstone.