Senator Decimus is, for the most part, a rich jerk. It's not exactly his fault, as he's a product of his times. He certainly lacks the scheming and ambition of his fellow senator Ratbat, but like most members of the Senate from his time period, he's simply lost touch with anything but maintaining the comfortable lifestyle to which he's become accustomed. In another era, he'd simply be a harmless dignitary, but with the class struggle erupting from his continued automation of the asteroid energon mines, he's sitting on a powder-keg just waiting to blow.