Ultimately, the Decepticons desire to protect their homeworld, even if it is at the expense of others. More than a few have a sense of honor, while others believe that Cybertron would be better protected by aggressive expansion. Also, the Decepticons are not exactly the most compassionate beings in the universe, but not all fight for greed. This tends to cause some conflict, given how generally every Decepticon thinks that they're the most powerful.
Unlike the Autobots, whose leader is a Prime bearing a Matrix, the Decepticons are led by the most powerful of their ranks. They are typically concerned with such things as conquering Cybertron, defeating the Autobots, amassing large quantities of energon, developing powerful weaponry, and beating people up. The Decepticons are one of the primary factions in the Transformers mythos. From the noun - 'deception' one who deceives. Decepticon (di-sep-ti-con) A member of a subversive sect or society.
