Thundercracker claims the skies as his arena. He looks down in contempt on those who cannot leave the ground — he considers them lesser beings. He will often attack the flightless beings below him for no other reason than to satisfy his scorn.
His superiority in this realm is the only thing he is sure of. Thundercracker is not entirely committed to the Decepticon cause, and even has some seemingly contradictory sympathy for the humans they terrorize. Fear of retribution from Megatron and the influence of his peers is usually enough to bury these doubts. Regardless, he needs constant reassurance from Skywarp and Starscream (which occasionally take the form of threats) that he's where he needs to be. Sometimes, his heart's just not in the job.
His alt-mode is a Modified F-15 Eagle.