Jetfire

Jetfire is compassionate, so some Autobots feel that he could be soft on their enemies or, even worse, he may turn on them after realizing his "cold calculations" swing the other way. Jetfire would find their misconceptions about science appalling.

(Backstory) He is portrayed as a former Decepticon who becomes an Autobot because he did not believe in all the destruction and violence the Decepticons were dedicated to.

On Cybertron before the war between the Autobots and Decepticons, jetfire was a scientist and explorer working with Starscream. Together, they investigated an uncharted planet, actually a prehistoric Earth, where they failed to find any signs of intelligent life. Jetfire wished to scrutinize the planet further, and moving in close enough to the planet, a polar wind storm swept him up and buried him beneath the Arctic ice. Starscream searched for his friend, but was unable to locate him and returned to Cybertron alone.

Millions of years later, in 1984, the Decepticons discovered the frozen jetfire, while draining heat energy from the Earth's core and reactivated him. Reunited with his old friend, Starscream, jetfire joined the Decepticon ranks. When the Autobots arrived, Skyfire engaged them in battle, and then rescued Sparkplug and Spike Witwicky when they became stranded on an ice floe. Unknowingly, he took the two to Megatron under the impression that he and the other Decepticons valued human life, but when Megatron took them as prisoners, jetfire started to question his allegiance. When Starscream ordered him to destroy the captured Autobot search party, he refused, and joined the Autobots.