Mudflap is a Decepticon. A really nasty Decepticon, who tends to beat the slag out of already beaten Autobots. This brutal exterior, however, masks a weaker interior filled with doubt about being a Decepticon. He wants to quit and hook up with the Autobots, but knows that his reputation keeps him from having a chance at joining. So he's stuck with the 'Cons, and lets his enemies know it by way of inflicting enormous amounts of pain on them.