Thunderwing was created eons ago by Unicron to find and destroy the Matrix of Leadership. His loyalty is only to his master, even if his master is dead, and he will use all resources possible to complete a mission, no matter which side of the war gets in his way.
At some point in the past Thunderwing was encased in a meteor of Dark Energon and fell into a deep sleep. Ages later, Megatron attempted to bring the meteor to Earth, only to be stopped by Optimus Prime and the Autobots. During the battle, Thunderwing was awakened and both the Dark Energon and his own components fell to the Earth.
