Starscream may be alligned with the Decepticons, but that doesn't mean he is loyal to Megatron. The former Sky Commander once protected a space station that held the remnaints of Dark Energon. He decided to join the villianous bots when Megatron was able to control the vile fluid, betraying his former friend, Jetfire. He has made it clear to his fellow Seekers that one day, he will usurp Megatron and claim the title as leader of the Decepticons. Unlike in any other continuity, Starscream is not the second in command of the Decepticons.